ประกวดราคาซื้อTransformer, 3 Phase, 33 kV, SC จํานวน 2 รายการ เลขที่ กจพ1-มป-010-2569

• เพื่อจัดหาหม้อแปลงไฟฟ้าสามเฟสที่มีคุณภาพและมาตรฐานสูงสำหรับระบบจำหน่ายไฟฟ้าของ กฟภ.
• เพื่อรองรับระบบจำหน่ายไฟฟ้า 22 kV และ 33 kV ที่มีความต้องการความทนทานต่อกระแสลัดวงจร
• เพื่อส่งเสริมอุตสาหกรรมการผลิตหม้อแปลงไฟฟ้าภายในประเทศ

• ออกแบบและผลิตหม้อแปลงไฟฟ้าสามเฟสตามมาตรฐาน TIS 384
• ดำเนินการทดสอบ Routine Test และ Type Test ตามที่กำหนด
• จัดทำเอกสารทางเทคนิค แคตตาล็อก และแบบรูปแสดงรายละเอียด
• ส่งมอบพัสดุ ณ สถานที่ของผู้เสนอราคาที่ผ่านเกณฑ์ระยะทางที่กำหนด
• รับผิดชอบค่าใช้จ่ายในการทดสอบเพื่อการตรวจรับ (Acceptance Test)
• รับประกันคุณภาพและดำเนินการแก้ไขกรณีชำรุดภายในระยะเวลารับประกัน

• หม้อแปลงไฟฟ้าสามเฟส ขนาด 500 kVA จำนวน 23 เครื่อง
• หม้อแปลงไฟฟ้าสามเฟส ขนาด 1,000 kVA จำนวน 4 เครื่อง
• รายงานผลการทดสอบ (Routine Test Report, Type Test Report)
• คู่มือการติดตั้ง การใช้งาน และการบำรุงรักษา
• รายการอะไหล่ (Part Lists)
• เอกสารรับรองมาตรฐานผลิตภัณฑ์ (TISI, ISO/IEC 17025)

• งวดที่ 1 (รายการที่ 1): 10 เครื่อง ภายใน 45 วัน
• งวดที่ 2 (รายการที่ 1): 13 เครื่อง ภายใน 15 วัน
• รายการที่ 2: 4 เครื่อง ภายใน 45 วัน
  (นับถัดจากวันลงนามในสัญญา)

• Eligibility Requirements: ต้องเป็นผู้ผลิตภายในประเทศ (Local Manufacturer)
• Standards Compliance: ต้องได้รับใบอนุญาตแสดงเครื่องหมายมาตรฐานผลิตภัณฑ์อุตสาหกรรม (มอก.)
• Experience: ต้องเป็นโรงงานที่ได้รับการรับรองระบบคุณภาพ ISO 9001
• Technical Capabilities: โรงงานต้องได้รับการรับรองความสามารถห้องปฏิบัติการทดสอบตามมาตรฐาน มอก. 17025 หรือ ISO/IEC 17025 ครอบคลุมหัวข้อการทดสอบที่กำหนด
• Personnel: -

• พิจารณาจากรายละเอียดทางเทคนิคที่ครบถ้วนตามสเปค (Specification No. RTRN-035/2568)
• การยื่นเอกสารสำคัญครบถ้วน (Critical Documents)
• การผ่านเกณฑ์การทดสอบและมาตรฐานห้องปฏิบัติการ
• ราคาและเงื่อนไขการส่งมอบ

• พิกัดกำลัง: 500 kVA และ 1,000 kVA
• แรงดันไฟฟ้า: 22 kV หรือ 33 kV / 416/240 V
• การต่อสาย: Dyn11
• ระบบระบายความร้อน: ONAN
• ความสามารถในการทนต่อกระแสลัดวงจรตามมาตรฐาน TIS 384 Part 5
• การเคลือบสี: ตามมาตรฐาน ISO 12944-5 (C3) ความหนาไม่น้อยกว่า 180 μm

• การส่งมอบ: ทยอยส่งมอบตามงวดงาน
• สถานที่ส่งมอบ: สถานที่ของผู้เสนอราคาภายในรัศมี 180 กม. จากกองจัดการโลจิสติกส์ภาคกลาง (รังสิต)
• การรับประกัน: ดำเนินการแก้ไขภายใน 30 วันหากชำรุดในระยะเวลารับประกัน
• ค่าใช้จ่ายการทดสอบ: คู่สัญญาเป็นผู้รับผิดชอบค่าใช้จ่ายในการทดสอบทั้งหมด

• Q: โครงการนี้อนุญาตให้ใช้ผลิตภัณฑ์นำเข้าหรือไม่? A: ไม่ได้ โครงการนี้กำหนดให้จัดซื้อพัสดุที่ผลิตภายในประเทศเท่านั้น
  • Q: สถานที่ส่งมอบต้องอยู่ไกลจากรังสิตเท่าใด? A: ต้องอยู่ภายในรัศมี 180 กิโลเมตรจากสำนักงานกองจัดการโลจิสติกส์ภาคกลาง (รังสิต)
  • Q: หากหม้อแปลงชำรุดในระยะประกัน ใครเป็นผู้รับผิดชอบ? A: คู่สัญญาต้องรับกลับไปแก้ไขให้ถูกต้องภายใน 30 วัน โดยเป็นผู้รับผิดชอบค่าใช้จ่ายทั้งหมด
  • Q: สามารถใช้ใบขึ้นทะเบียน PEA Product Acceptance แทนแคตตาล็อกได้หรือไม่? A: ไม่ได้ โครงการนี้ยกเว้นเงื่อนไขดังกล่าว ผู้เสนอราคาต้องยื่นแคตตาล็อกและแบบรูปรายละเอียดทางเทคนิคโดยตรง
  • Q: การทดสอบเพื่อการตรวจรับ (Acceptance Test) ใครเป็นผู้จ่ายค่าใช้จ่าย? A: คู่สัญญาเป็นผู้รับผิดชอบค่าใช้จ่ายในการทดสอบทั้งหมด
  • Q: กรณีหม้อแปลง 500 kVA ต้องเป็นชนิดใด? A: ต้องเป็นชนิด Hermetically Sealed และ Completely oil filled (ไม่มีถุงลม)
  • Q: กรณีหม้อแปลง 1,000 kVA ต้องเป็นชนิดใด? A: ต้องเป็นชนิด Conservator System
  • Q: การทดสอบ Dry film thickness ต้องทำอย่างไร? A: ต้องวัดความหนาไม่น้อยกว่า 180 μm ตามมาตรฐาน ISO 12944-5
  • Q: หากตำแหน่งการพ่นรหัส PEA ไม่สามารถทำได้ตามกำหนดต้องทำอย่างไร? A: ให้ติดต่อกองบริหารจัดการหม้อแปลงระบบจำหน่ายเพื่อกำหนดตำแหน่งใหม่
  • Q: การขนย้ายพัสดุออกจากสถานที่คู่สัญญาใช้เวลานานเท่าใด? A: กฟภ. จะดำเนินการขนย้ายภายใน 15 วันนับจากวันรับพัสดุเข้าบัญชี

• 1 -
  PROVINCIAL ELECTRICITY AUTHORITY
  การไฟฟ้าส่วนภูมิภาค ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 1 of 51
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจ 1-มป-010-2569
  C
  C1
  1a
  1b
  Material, equipment, and specifications for TIIREE-PHASE TRANSFORMERS FOR 22 kV AND
  33 kV 50 Hz DISTRIBUTION SYSTEMS WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  General material and packing instructions
  Additional to the general instructions, the following shall be observed:
  Scope
  These specifications cover three-phase transformers, oil-immersed, natural self-cooled (ONAN), power
  range from 50 kVA to 2,000 kVA, designed and constructed to withstand without damage the thermal
  and dynamic effects of external short circuits, suitably designed for outdoor installation on 22 kV and
  33 kV 50 Hz distribution systems. Hereinafter referred to as “transformers”
  Standards
  The transformers shall be manufactured and tested in accordance with the following standards:
  Thailand Industrial Standard (TIS)
  TIS 384 part 1-2567
  TIS 384 part 2-2567
  TIS 384 part 3-2567
  Power transformers Part 1: General
  Power transformers - Part 2: Temperature rise for liquid-immersed
  transformers
  Power transformers - Part 3: Insulation levels, dielectric tests and external
  clearances in air
  TIS 384 part 5-2567
  Power transformers - Part 5: Ability to withstand short circuit
  EME
  PEA
  The Thai Industrial Standard Institute (TISI) certification in according to TIS 384 Part 1 of the
  proposed transformers shall be submitted with the bid.
  And all other relevant standards, unless otherwise specified in these specifications.
  PEA will also accept the transformers and accessories tested in accordance with the later edition of the
  above standards.
  PEA will also accept the type test report in accordance with the previous edition of the above standards,
  if there is no significant change in any test items or no additional test item(s) compared with the above
  standards. On the other hand, if there is significant change in any test items or there are any additional
  test items. the previous edition type test report with the additional test report(s) of the significant change
  test item(s) and/or additional test item(s) will be also accepted.
• 2 -
  การไฟฟ้าส่วนเก
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev, No.:
  le
  Principal requirement
  1c.1
  Service conditions and installation
  Form No.
  Page 2 of 5t
  The transformers shall be designed and constructed for outdoor installation and operation under the
  following conditions:
  1c.2
  Rating
  1c.2.1
  Altitude
  : up to 1,000 m above sea level
  Ambient air temperature
  :
  50°C, maximum
  : 40 °C, monthly average, of the hottest month
  Relative humidity
  Climate condition
  :
  up to 94%
  :
  tropical climate
  Transformer Rating
  Table 1 Transformer installation
  Installation
  (KVA)
  50·250
  on concrete pole and on platform
  315
  1.500
  2.000
  on platform and on concrete foundation
  on concrete foundation
  Rated power
  The rated power, on continuous operation, for transformers shall be as follows:
  50 KVA
  250 KVA
  100 KVA
  315 KVA
  160 KVA
  400 KVA
  500 KVA
  630 KVA
  800 KVA
  1,000 KVA 2,000 KVA
  1,250 kVA
  1.500 kVA
  1c.2.2 Rated frequency: 50 Hz
  1c.2.3 Rated voltages
  Rated Primary Voltage
  :
  22 kV or 33 kV
  Rated Secondary Voltage
  :
  416/240 V
  1c.2.4 Connection and phase displacement symbol
  : Dynll
  1c.2.5 Tapping range: ±2 x 2.5% of rated primary voltage
  EME
  PEA
• 3 -
  1! ฟ้าสวนก
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025|| Rev. No.:
  1c.2.6 Losses and Short-circuit impedance
  1c.2.7
  Form No.
  Page 3 of 51
  The specified or guaranteed losses plus positive tolerance for each transformer unit shall not be more
  than the losses shown in Table 2.
  Short-circuit impedance shall be measured on the principle tapping of 22 kV or 33 kV at ambient
  temperature and then corrected to 75°C.
  Short-circuit impedance of the offered transformers shall be as specified in Table 2, with a tolerance
  within ±10%. However, for transformers with a rating of 500 kVA, the short-circuit impedance at 75°C
  shall be 6.5% or more.
  Table 2 Losses and short circuit impedance
  EME
  PEA
  Transformer
  Watt Loss (W)
  Short-circuit
  Rating
  No-load loss, for system voltage of:
  (KVA)
  22 kV
  33 kV
  Load loss
  at 75°C
  Impedance at 75°C
  (%)
  50
  110
  170
  875
  4
  100
  180
  260
  1450
  4
  160
  260
  370
  2000
  4
  250
  360
  520
  2750
  4
  315
  440
  630
  3250
  4
  400
  520
  750
  3850
  4
  500
  610
  900
  4600
  6.5 or more
  630
  680
  1050
  5600
  6
  800
  800
  1150
  7000
  6
  1.000
  940
  1300
  9000
  6
  1,250
  1150
  1530
  11000
  6
  1.500
  1380
  1850
  13200
  6
  2.000
  1800
  2140
  18000
  6
  Limits of temperature-rise, above 50°C ambient temperature
  Of top oil
  Of winding
  : not more than 50 K,
  : not more than 55 K,
• 4 -
  วาระ ฟาลา กมล
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025· Rev. No.:
  1
  Form No.
  ;
  Page 4 of 51
  1c.2.8 Insulation level
  The transformers shall have insulation level of HV winding, LV winding and connected part as specified
  in Table 3:
  Table 3 Insulation level
  Nominal System Voltage
  Full Wave Lightning Impulse
  Power Frequency Test Voltage,
  (kV, r.m.s.)
  22
  33
  Test Voltage (kV, peak)
  1-min (kV, r.m.s.)
  125
  50
  170
  70
  0.416/0.24
  30
  10
  1c.2.9 Minimum clearance in air
  The shortest distance between any metallic part of the bushing terminal and any part of the transformer
  shall be not less than minimum air clearance requirements specified in Table 4.,
  Table 4 Minimum clearance in air
  Minimum air clearance
  Nominal System Voltage
  Line to earth
  Phase to phase
  (kV, r.m.s.)
  22
  33
  (mm)
  225
  (mm)
  225
  320
  320
  1c.3
  Core and windings
  The cores and windings of transformers shall be as follows:
  EME
  PEA
  Table 5 Core and windings
  Transformer
  Construction
  Rating
  of Core
  (KVA)
  HV and LV
  Windings shall
  be made of
  Construction of Windings
  HV winding
  LV winding
  50-2.000
  According to
  manufacturer’s
  standard
  copper only
  According to
  manufacturer’s
  standard
  According to
  manufacturer’s
  standard
• 5-
  การไฟฟ้าส่วนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  1c.4
  Oil preservation system
  Form No.
  Page 5 of 51
  The transformers of 50 KVA to 500 kVA shall be permanently sealed and completely oil filled system
  (without gas cushion) type (usually corrugated tank). The tank cover shall be bolt tightened to the tank with suitable gasket sealing.
  The transformers of 630 kVA to 2,000 kVA shall be conservator system type.
  1c.5 Tank and Tank cover
  EME
  Tank and tank cover shall be constructed of welded steel plate suitable reinforced. The joints between
  the tank and cover shall be provided with suitable flanges properly bolted together with gaskets.
  Tank cover shall have 90° downward bent edges on all sides to protect the gasket under the top cover
  from direct exposure to weather.
  The tank and tank cover shall be electrically connected to ensure equipotential bonding.
  Gaskets between metal surfaces shall be set in grooves or held in position by retainers so arranged that
  all parts are bolted metal-to-metal. The gaskets shall be made of resilient material which will no
  deteriorate under the action of hot oil and will remain oil-tight. Gaskets of such material which can be
  casily damaged by over-pressing are not acceptable.
  The transformer tank shall be finished with mounting brackets for surge arresters (Surge arresters
  polymer housing type supplied by PEA) and shall be furnished with three (3) earthing terminals
  provided for ground leads of surge arresters, see Drawing No. SB4-015/68001.
  The bidders have to give dimensions of the transformer tank which passed type test and short-circuit
  withstand tests in Design data and guarantee for the proposed transformers.
  Tolerance of the dimensions of the transformer tank for the proposed transformers shall be within ±3
  percent of the declared dimensions which given by the bidders in Design data and guarantee for the
  proposed transformers, otherwise shall be rejected.
  The manufacturer’s serial number shall be dented on the transformer tank cover or dented on the metal
  plate and welded on the transformer tank cover.
  The manufacture shall prepare 3 mm diameter holes for security seals threading; The first position, the
  hole shall be drilled at bolt which fix tank and cover of the transformers and the second position, the
  hole shall be drilled at the top right of transformer nameplate as Figure 1.
  The security seals will be installed by PEA after any transformers pass the witness test or acceptance
  test or others depend on PEA’s committee.
  CLA
• 6 -
  การไฟฟ้าส่วน
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  EME
  PEA
  Approved date: 17 SEP 2025
  Rev. No.:
  Для
  TANK
  Security Seal
  1st Position
  Nameplate Nameplate Base
  Security Scal
  2 Position
  Figure 1 Security seal installation
  Form No.
  Page 6 of 51
  Ø3
  Security Seal
• 7 -
  การไฟฟ้าส่วนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: :17 SEP 2025 Rev. No.:
  1c.5.1
  Requirement of transformer dimension
  Form No.
  Page 7 of 51
  The dimensional requirements of the transformer to be installed on a concrete pole (50-250 kVA) shall
  be as follows and specified in Table 6:
  (1) The total height of the transformer shall be specified as follows, following spacing ‘H1’;
  (1.1) For 22 kV system shall not be more than 1.500 mm.
  (1.2) For 33 kV system shall not be more than 1,650 mm.
  (2) The total width of the transformer tank shall not be more than 1,250 mm, following spacing ‘W1’;
  (3) The distance between the upper supporting lug and the bottom lug shall be 600 mm spacing; 500 mm
  or 400 mm spacing may be used when the tank height of the transformer is not more than 600 mm
  with a tolerance rang of 0 to 13 mm, following spacing ‘A’.
  (4) The distance between the edge of bolt slot of the bottom supporting lug and the bottom of the
  transformer tank shall not be more than 200 mm following spacing, following spacing ‘B’.
  (5) The distance between the tank cover (Top plate) and fins for installing carthing terminal of surge
  arrester shall not be less than 200 mm. following spacing “C”.
  (6) The distance between hole of the mounting bracket for installing surge arrester and stud of HV
  bushing shall not be less than 200 mm, following spacing ‘D’.
  (7) The distance between the LV terminal connector and the supporting lugs shall not be less than 250 mm.
  following spacing “E’.
  E
  A
  क
  Back view
  W1
  E
  Side view
  с
  TANK
  EMFigure 2 Measuring point of the requirements for the pole-mounted transformers installation (50-250 kVA)
  PLA
• 8 -
  การไฟฟ้าส่วนภูมิ
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 8 of 51
  Table 6 Dimensional requirements for the pole-mounted transformers installation (50-250 kVA)
  Requirement of transformer dimension
  Transformer design
  H1
  Wi
  A”
  B
  C
  D
  E
  (mm)
  (mm)
  (mm)
  (mm)
  (mm)
  (mm)
  (mm)
  For 22 kV system
  Not more
  than 1.500
  For 33 kV system
  Not more
  than 1,650
  Not more
  than 1,250
  Not more
  Not less
  Not less
  Not less
  600(+3)
  than 200
  than 200
  than 200
  than 250
  "
  Note: The distance between supporting lugs may be used 500 mm or 400 mm spacing when the tank height
  of the transformer is not more than 600 mm
  1c.5.2 Tank finish
  (1) Interior surface
  The Interior surface shall be finished oil resistant paint or vanish.
  (2) Exterior surface
  The painting system will be suitable for an exterior servicing at medium atmospheric corrosivity
  in accordance with ISO 12944-5:2019 and system number is as C3.06 in Table C.3 - Paint systems
  for carbon steel for corrosivity category C3 as following:
  Priming coat: The number of coats is one (1). The binder type shall be Epoxy (EP). The Type
  of primer shall be miscellaneous (Misc). The nominal dry film thickness shall be in range of
  80 to 160 μm.
  Subsequent coat: The number of coats is one (1) of Polyurethane (PUR) topcoat with RAL 7036
  gray colour.
  The total number of coats is two (2) coats. The nominal dry film thickness of whole paint system
  shall not be less than 180 μm.
  EME
  PEA
• 9 -
  Form No.
  Page 9 of 51
  การไฟฟ้าส่วนสภาพ
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: ·17 SEP 2025 Rev. No.:
  1c.5.3.1 Measuring points
  The dry film thickness shall be spot checked for cach layer of coating (only for the type test). The
  number and position of spot checks are specified below:
  1c.5.3 Dry film thickness test
  (1) Top and bottom of Tank
  Top and bottom of Tank
  : Not less than 10 points
  1/3 of length
  1/6 of length
  X
  X
  X
  X
  X
  X
  X
  X
  X
  Figure 3 Measuring points for the top and bottom of tank
  (2) Front, Back, and Side of Tank
  Front and Back of Tank
  Side of Tank
  : Not less than 20 points for transformers that no have side of fin or,
  Not less than 26 points for transformers that have side of the fin.
  : Not less than 10 points.
  (2.1) For transformers of permanently scaled typc
  EME
  PEA
  Y
  tex

x Ox
✪x.
x ox
x☹
HI
H
H3
–W2
WI
W3
*G…IM
3400.
XQ X
“I
XOX
Hi
-D
H2
FRONT VEN
SIDE VIEW
Figure 4 Measuring points for transformers of permanently sealed type.

• 10 -
  nosi wwbanu gùnte
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 10 of 51
  The distance for spot checking of permanently sealed type specified in Table 7:
  Table 7 Distance for spot checking of permanently sealed type
  דיד
  Symbols
  Length
  Symbols
  Length
  a
  About 1/2 of width (W1)
  LL
  About 1/2 of height (H1)
  b
  About 1/5 of width (W2)
  V
  About 1/2 of height (H3)
  с
  About 2/5 of width (W2)
  X
  About 1/4 of height (H2)
  d
  About 3/5 of width (W2)
  میں
  e
  About 4/5 of width (W2)
  N
  About 2/4 of height (H2)
  About 3/4 of height (112)
  f
  About 1/2 of width (W3)
  g
  About 1/3 of depth (D)
  i
  About 2/3 of depth (D)
  (2.2) For transformers of conservator system type
  d
  H1
  CHI
  B
  H2
  H2
  H3
  HB
  1:
  1:
  k
  DI
  WH
  -W2-
  W3
  FRONT VEN
  BOF WEW
  -D2–
  EME
  PEA
  Dreservare
  Figure 5 Measuring point for transformers of conservator system type.
  The distance for spot checking of conservator system type specified in Table 8:
  !
• 11 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 1 of 51
  Length
  Symbols
  Table 8 Distance for spot checking of conservator system type
  Symbols
  Length
  Â
  a
  About 1/2 of height (W1)
  m
  About 1/5 of depth (D2)
  b
  About 1/6 of height (W2)
  נו
  с
  About 2/6 of height (W2)
  C
  About 2/5 of depth (D2)
  About 3/5 of depth (D2)
  d
  About 3/6 of height (W2)
  P
  About 4/5 of depth (D2)
  с
  About 4/6 of height (W2)
  LI
  About 1/2 of height (H1)
  f
  About 5/6 of height (W2)
  V
  About 1/2 of width (H3)
  الت
  g
  About 1/2 of height (W3)
  X
  About 1/4 of width (H2)
  i
  About 1/5 of depth (D1)
  y
  About 2/4 of width (I2)
  About 2/5 of depth (11)
  N
  About 3/4 of width (H2)
  k
  About 3/5 of depth (DI)
  I
  About 4/5 of depth (D1)
  1c.5.3.2 Test report
  The required information in the dry film thickness test report shall be at least the following items:
  (1) Transformer information
  (1.1) Manufacturer’s name
  (1.2) Model
  (1.3) Serial number
  (1.4) Number of phases
  (1.5) Rated voltage of the high-voltage winding
  (1.6) Rated voltage of the low-voltage winding
  (1,7) Rated frequency
  EME
  SE
  (1.8) Rated power
  (1.9) Rated current of the high-voltage winding
  (1.10) Rated current of the low-voltage winding
  (2) Painted information
  (2.1) Coating system (e.g. flow coating or spraying)
  (2.2) The information for each coating (c.g. Priming coat, Subsequent coat) minimum as
  follows:
  Type of material
  Paint Manufacturer

Require minimum dry film thickness (μm) as specified

• 12 -
  การไฟฟ้าลวนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Form No.
  Page 12 of 51
  Approved date:
  17 SEP 2025 Rev. No.:

Actual dry film thickness (um) (3 readings per I spot check)
1c.6
(2.3) Technical Data of coats
(2.4) Painting Procedure
The bidders have to subinit the test report, conducted by the testing laboratories or the manufacturers
themselves, with the bid. The Item offered without submitting the dry film thickness test report shall be
rejected.
PEA reserve the right to send representatives to inspect and witness the test.
The cost of all tests and reports shall be borne by the bidder/manufacturers/contractor.
Tappings
The primary windings of the transformers shall be provided with full capacity of externally-operated
off-circuit tap changers.
The externally-operated off-circuit tap changer shall be designed for de-energized operation with the
operating handle brought out through the cover of the tank. The operating handle shall have provision
for locking and shall give visual indication of the tapping position without unlocking.
The tap changer shall have a locking device to prevent improper use.
The operating handle shall be rotated in clockwise direction from a high tap voltage to a lower tap
voltage. The tap changer shall be provided with stops to identify the highest and lowest tap position.
The tap changer positions shall be identified by the numbers in sequence. The number “1” shall be
designated to the highest tap voltage. Consequently the number “5” indicates the lowest tap voltage.
These identifications shall be in perfect correspondence to those indicated in the connection diagram on
the nameplate. All five positions of the tap changer shall be operative.
The tap positions shall be indelibly marked with weather-proof paint and in a colour which shall present
distinctive contrast to the surrounding material.
The operating handle of tap changer shall be made from non-corrosive metal. Plastic is not acceptable.
EME
PEA

• 13 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  1 c.7
  Initial oil filling
  1c.8
  1 c.8.1
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 13 of 51
  The transformers shall be filled with high-quality, clean. and dry oil that complies with IEC 60296.
  The oil shall be free from Polychlorinated biphenyls (PCBs).
  The breakdown voltage of the mineral insulating oils after filling in new transformers prior to
  energization shall be no less than 55 kV, as specified in IEC 60422, and test method in accordance with
  IEC 60156.
  Bushings
  Detail dimensions, creepage distances and current rating
  HV Bushing shall have dimensions and minimum creepage distance specified in Table 9.
  Table 9 Detail dimensions, creepage distances and minimum air clearance of HV Bushing
  Bushing
  High-voltage bushings for
  22 kV system
  High-voltage bushings for
  33 kV system
  Dimensions
  Minimum
  creepage distance
  According to
  Not less than 600 mm
  DIN EN 50180, Type 24-250/P3
  According to
  Not less than 900 mm
  DIN EN 50180. Type 36-250/P3
  LV Bushing shall have dimensions according to DIN 42539 with current rating specified in Table 10.
  Table 10 Current rating of LV Bushing
  Transformer Rating
  Current rating
  (KVA)
  (A)
  50 - 160
  250
  250 - 315
  630
  400 630
  1.000
  800 - 1,250
  2.000
  1.500 2.000
  3.150
  1c.8.2 Numbers, location, terminal markings, and tank shape
  EME
  Each transformer shall have three (3) high-voltage bushings and four (4) low-voltage bushings located
  on the cover of the tank.
  Secondary neutral point of the transformers shall be brought out by separate-insulated bushing(s) with
  a rated current same as the line bushing.
  The HV bushings shall not be completed with the arcing horns.
  :
  ¡
• 14 -
  การไฟฟ้าส่วนภูมิภา
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  EME
  PLA
  Approved date: 17 SEP 2025 Rev. No.:
  The bushings shall be located as shown in Figures 6.
  Low-Voltage Side
  a b c
  с
  1
  Form No.
  Page 14 of 51
  Low-Voltage Side
  n
  с
  b
  A
  દી
  A B C
  C B A
  High Voltage Side
  High-Voltage Side
  50-250 KVA Tank top view
  315-2,000 kVA Tank top view
  Figure 6 Bushing location
  The letters A. B, C, a, b, c, and n shall be durably marked on transformer tanks beside bushings
  consequently. The height of the symbols shall be not less than 30 mm. Mark by sticker is not accepted.
  ic.8.3 Material
  Transformer bushings shall be made of good commercial-grade wet-process porcelain.
  The entire porcelain surface of the bushings that will be exposed after assembly shall be glazed.
  The colour of the glaze shall be brown.
  1c.8.4 Electrical characteristics
  The transformer bushings shall be capable of withstanding the impulse and low-frequency voltage as
  specified in Table 11:
  Table 11 Electrical characteristics of bushing
  Impulse Full Wave
  Low-frequency, 50 Hz (kV, r.m.s.)
  Bushing
  (kV, peak)
  Dry 1-minute
  Wet 10-second
  High-voltage bushings for
  125
  55
  50
  22 kV system
  High-voltage bushings for
  170
  77
  70
  33 kV system
  Low-voltage bushings
  30
  10
  10
  1c.8.5 Test report
  The bidders have to submit the test report of the HV and LV bushing with the bid to confirm the electrical
  characteristics in Table 11 Electrical characteristics of bushing, the bidders who cannot submit will
  be rejected. The bushing test can be conducted by the manufacturer or third-party laboratories.
• 15 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 15 of 51
  1c.9
  Terminal connectors
  1 c.9.1
  HV Terminal connectors
  HV bushings shall be equipped with solderless clamp type connectors for aluminium conductor diameter
  range from 7.5 mm to 12.6 mm (sizes 35-95 mm).
  1c.9.2
  LV Terminal connectors
  EME
  PEA
  Only for 50 KVA to 1,250 kVA transformers:
  IV bushings shall be equipped with terminal pad connectors (stud type connectors are preferable), cast
  from high conductivity bronze and hot-tin dipped. The terminal pad connectors shall be seamless.
  The terminal pads shall be drilled in accordance with NEMA Standards (9/16” holes on 1 3/4′′ centers);
  each hole shall be furnished with one (1) bolt M12 x 60 mm (of at least 50 mm thread length), one (1)
  nut. two (2) flat washers, and one (1) lock washer; details of terminal pads shall be according to Drawing
  No. SB4-015/68001. The connectors shall be provided with mounting hardware (bolts, nuts, washers,
  and lock washers) of stainless steel or better.
  Only for 1,500 kVA to 2.000 kVA transformers:
  LV bushings shall be equipped with solderless clamp type connectors (stud type connectors are
  preferable), high conductivity bronze and hot-tin dipped, for aluminium and copper conductor sizes, and
  number of circuits take off shall be as Table 12:
  Table 12 Terminal connectors for 1,500 kVA to 2,000 kVA transformers
  Transformer Rating
  (KVA)
  1,500
  2.000
  Applicable to Aluminium and Copper Conductors
  Number of
  diameter range (mm)
  sizes (mm2)
  Circuits
  18.4 - 29.2
  240 - 500
  4
  18.4 - 29.2
  240 - 500
  6
  The connectors shall be provided with mounting hardware (bolts, nuts, washers, and lock washers) of
  stainless steel or better. The details of connectors shall be according to Drawing No. SB4-015/68001.
• 16 -
  การไฟฟ้าส
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 16 of 51
  Ic.10
  Accessories
  1c.10.1 List of Accessories
  The accessories listed in the Table 13 shall be installed along with the transformer.
  Table 13 Lists of Accessories
  No.
  KVA
  Accessories
  50-250
  315-500 630-800
  1000-2000
  ✓
  1
  HV bushings with terminal connectors
  ✓
  2
  LV bushings with terminal connectors
  ✓
  ✓
  ✓
  3
  Bird guard cap (bushing cover)
  ✓
  ✓
  ✓
  4
  Earthing terminal for surge arrester
  ✓
  ✓
  ✓
  ✓
  5
  Tap changer
  ✓
  ✓
  6
  Thermometer pocket
  ✓
  ✓
  ✓
  7
  Nameplate
  ✓
  ✓
  ✓
  ✓
  8
  Oil drain valve with plug or cap
  ✓
  ✓
  9
  Sludge drain plug
  ✓
  ✓
  10
  Earthing terminal with solderless clamp typc
  ✓
  connector
  11
  Lifting lugs
  12
  Lifting eyes on the cover
  13
  Oil level gauge
  14
  Compression type cable lug
  15
  Pressure relief valve
  16
  Oil filling plug on the tank cover
  17
  18
  Supporting lugs
  Oil conservator. with dehydrating breather. oil
  level gauge and oil filling cap
  19 Transport rollers
  20
  21
  Dial type thennometer with adjustable
  contact(s)
  Double float Buchholz relay having two (2)
  contacts (for alarm and tripping)
  22 Other necessary accessories according to
  EME
  manufacturer’s design can be installed (if any)
  PEA Note:
  The items on the list shall be installed
  ✓
  ✓
  ✓
  ✓
  ✓
  ✓
  ✓
  ✓

1
✓
✓
1

• 17 -
  การไฟฟ้าส่วนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025 Rev, No.:
  1c.10.2 Details of Accessories
  Form No.
  Page 17 of 51
  (1) HV and LV bushings, with terminal connectors (See 1c.8 and 1c.9)
  (2) Bird guard caps (bushing covers), ultra-violet and track resistant material, e.g. polypropylene,
  ncoprene, etc; which is suitable for exposure to sunlight
  (3) Farthing terminals for surge arresters, with solderless clamp type connector suitable for flexible
  copper insulated ground lead size 16 mm2, 430 mm long. (See Drawing No. SB4-015/68001)
  (4) Tap changer (See 1c.6)
  (5) Thermometer pocket, transformers shall have a thermometer pocket to allow the measuring of the
  top-oil temperature. This pocket shall be placed as shown in the EN 50216-4 (type A1). The pocket
  shall be provided with a corrosion-proof cap. The thread shall be protected with silicone-grease.
  Dimensions of the thermometer pocket in mm are shown in Figure 7.
  ए

• max 36
  30 MAMA
  涨
  EME
  PEA
  Figure 7 Dimensions of thermometer pockets
  (6) Nameplate (See 1c.12)
  (7) Oil drain valve with plug or cap, installed at the lower part of the tank
  (8) Sludge drain plug, installed at the bottom of the tank
  (9) Earthing terminal, with solderless clamp type connector suitable for steel stranded conductor
  diameter of 9.0 mm (size 50 mm2); complete with lock washer of stainless steel or better.
  (10) Compression type cable lugs, for aluminium conductor diameter of 7.5-9.0 mm (sizes 35-50 mm2),
  suitable for connecting between IIV bushings and surge arrester lead conductors.
  (11) Supporting lugs for hanging the transformer tank to pole by using two (2) MI6 machine bolts.
  The lugs shall be 600 mm spacing; 500 mm or 400 mm spacing may be used when the tank height
  of the transformer is not more than 600 mm. (See Drawing No. SB4-015/68001)

• 18 -
  ฟฟ้าเม
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025
  Rev. No.:
  Form No.
  Page 18 of 51
  1c.11
  (12) Oil conservator with dehydrating breather and oil level gauge. The cylinder of dehydrating breather
  shall be of transparent glass. The dehydrating breather shall be easy replaced and filled with silica-
  gel not less than 1.0 kg.
  Mass
  The mass of the proposed transformers, including oil and accessories shall be specified in Table 14.
  Table 14 Mass
  Transformer Rating (KVA)
  Maximum allowable mass (kg)
  1c.12
  EME
  50 - 160
  250
  Not more than 1,000
  Not more than 1,200
  Tolerance for the mass of proposed transformers, including oil and accessories shall be within
  ± 5 percent of the declared mass of transformers which pass the type test and short-circuit withstand
  tests given by the bidders in Design data and guarantee for the proposed transformers. However, the
  maximum mass shall not exceed the mass specified in Table 14.
  If the mass of the proposed transformers, including oil and accessories exceeds ± 5 percent of the
  declared mass or exceeds the maximum allowable mass, the transformers shall be rejected.
  Nameplate
  The following minimum nameplate information shall be legibly and durably inscribed on the metal part
  of the nameplate:
  (1) Kind of transformer
  (2) Number of this standard
  (3) Manufacturer’s name, county, and town where the transformer was assembled
  (4) Manufacturer’s serial number
  (5) Model
  (6) Year of manufacture
  (7) Number of phases
  (8) Rated power in KVA
  (9) Rated frequency in Hz
  (10) Rated voltage in V
  (11) Rated current in A
  (12) Connection and phase displacement symbol
  (13) Short-circuit impedance in %
  (14) Type of cooling
• 19 -
  PROVINCIAL ELECTRICITY AUTHORITY
  การไฟฟ้าส่วนภูมิภาค ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITHI ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025·
  Rev. No.:
  (15) Total mass in kg
  Form No.
  Page 19 of 51
  (16) Oil quantity in liters
  (17) Type of insulating liquid
  (18) Rated secondary short-circuit withstand current in kA r.m.s.
  (19) Short notation of insulation levels
  (20) Tapping voltages in V
  (21) Guaranteed maximum temperature rise of top oil and winding
  (22) Connection diagram
  (23) Wording “SHORT CIRCUIT WITHSTAND”
  (24) Material of HV and LV winding such as copper winding, copper foil, etc.
  (25) Guaranteed losses (load loss at 75” and no-load loss)
  (26) Type of core
  (27) PEA’s code number
  (28) Contract number and/or PO number
  1c.13 Marking
  EME
  FE
  The markings listed below shall be at the position that enables clear observation, legibly and durably as
  follows:
  (1) Wording “SHORT CIRCUIT WITHSTAND”
  The wording “SHORT CIRCUIT WITHSTAND” shall be painted in orange on the transformer
  tank (for transformer having no conservator) or on the conservator tank (for transformer having
  conservator).
  (2) PEA’s code number
  The details of the PEA’s code number painting are specified in Annex A. The PEA’s code number
  shall be given by PEA after the final of bid consideration.
  (3) Rated power
  Rated power shall be indelibly marked on the metal plate of weatherproof material. installed in
  front of the transformer.
  (4) Thai Industrial Standards (TIS) marking
  The Thai Industrial Standards (TIS) certification mark shall be indelibly marked on the metal plate
  of weatherproof material, indicated on the transformer tank.
• 20 -
  กาตุไฟฟ้าส่วน: 16
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  ld
  Tests and test reports
  1d.1
  Routine tests
  Form No.
  Page 20 of 51
  1d.2
  EME
  FLA
  Each transformer shall pass the manufacturer’s standard routine tests, and also pass the relevant
  standards.
  The routine tests shall be carried out by the manufacturer’s laboratorics which accredited under
  TIS 17025 or ISO/IEC 17025, with the scope of accreditation covering at least the following test items:
  (1) Measurement of winding resistance
  (2) Measurement of voltage ratio and check of phase displacement
  (3) Measurement of short-circuit impedance and load loss
  (4) Measurement of no-load loss and current
  (5) Applied voltage test
  (6) Induced voltage withstand test
  (7) Leak testing with pressure for liquid-immersed transformers (tightness test)
  (8) Check of core and frame insulation”
  Note: For transformers where the core and frame earth connections are not accessible when the
  transformer is liquid filled, the insulation shall be tested at 500 V d.c. for 1 min without
  breakdown before the active part is installed in the tank.
  The certification and scope of accreditation of the manufacturer’s laboratories shall be submitted
  with the bid.
  The routine test reports of each transformer shall be submitted with shipment/delivery.
  Type test and Short-circuit withstand tests
  (1) For the proposed transformers of power rating 50 kVA to 250 kVA:
  The transformers shall be passed all items of type test and short circuit withstand test according to
  1d.2.1 Test procedure. The test result shall be included in one (1) test report. The test report shall
  be issued or approved by the same 1d.2.3 Testing laboratories specified below, otherwise will be
  rejected.
  (2) For the proposed transformers of power rating more than 250 KVA:
  CASE 1: The ability to withstand the dynamic effects of short circuit demonstrate by test
  The transformers shall be passed all items of type test and short circuit withstand test
  according to 1d.2.1 Test procedure. The test result shall be included in one (1) test
  report. The test report shall be issued or approved by the same 1d.2.3 Testing
  laboratories specified below, otherwise will be rejected.
• 21 -
  างไฟพาลาด
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025 Rev. No.:
  Form No.
  Page 21 of 51
  CASE 2: The ability to withstand the dynamic effects of short circuit demonstrate by
  comparison with a reference transformer
  PEA also accept evaluation of the ability to withstand the dynamic effects of short
  circuit by comparison with a reference transformer which has passed the short-circuit
  test successfully, see Annex C.
  In this case, the transformers shall be passed the following type tests in accordance with
  the relevant standards:
  (1) Temperature-rise test
  (2) Full wave lightning impulse test
  (3) Measurement of no-load loss and current at 90 % and 110% of rated voltage
  Type test shall be made on only one (1) unit of cach rating. The test result shall be included in one
  (1) test report. The test report shall be issued or approved by the same 1d.2.3 Testing laboratories
  specified below, otherwise will be rejected.
  Id.2.1 Test procedure
  EME
  PLA
  Each transformer of 50 kVA to 250 kVA and the reference transformers, as delineated by its own unique
  serial number, is required to pass a complete type test and short-circuit withstand test following the
  procedures listed below:
  (1) Prior to short circuit testing, each individual transformer must pass the routine tests “. measurement
  of no-load loss and current at 90 % and 110% of rated voltage and temperature-rise tests. Criteria
  for the temperature-rise test is presented in 1e.2.7 “Limits of temperature-rise”
  (2) Upon successfully passing the temperature-rise test, each transformer must then successfully pass
  a short circuit withstand test “’
  (3) Finally, lightning impulse shall be tested and all the routine tests” including measurement of
  no-load loss and current at 90 % and 110% of rated voltage shall be repeated. Each transformer
  shall pass the routine test, measurement of no-load loss and current at 90 % and 110% of rated
  voltage and lightning impulse test.
  Note:
  Routine tests, as specified in 1d.I shall be conducted, except for the cheek of core and frame insulation.
  The transformers shall be designed and constructed to withstand without damage by the thermal and dynamic
  effects of the external short circuit in accordance with the IEC 60076-5.
  The duration of the current 1 to be used for the calculation of the thermal ability to withstand short circuit
  shall be 2 s and the initial temperature for calculation shall be 105°C.
  The total number of tests shall be nine made in a different position of the tap-changer according to IEC
  60076-5. The duration of each test shall be 0.5 s
• 22 -
  analwwnánusŭn^P
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 22 of 51
  PEA reserves the right to send representatives to witness the test.
  The cost of all tests and reports shall be borne by the bidders/manufacturers.
  1d.2.2 Test report
  (1) For transformers with rating of 50 kVA to 250 kVA:
  The bidders have to submit the type test and short-circuit withstand test reports of transformers
  identical to the proposed transformer with the bid, otherwise shall be rejected.
  (2) For transformers with rating of more than 250 kVA:
  CASE 1: The ability to withstand the dynamic effects of short circuit demonstrate by test
  The bidders have to submit type test and short-circuit withstand test reports of
  transformers identical to the proposed transformer with the bid, otherwise shall be
  rejected, or
  CASE 2: The ability to withstand the dynamic effects of short circuit demonstrate by
  comparison with a reference transformer
  The bidders have to submit the following documents with the bid, otherwise shall be
  rejected.

1. The type test report of transformers identical to the proposed transformer of three (3)
   items as follows:

Temperature-rise test
Full wave lightning impulse test
Measurement of no-load loss and current at 90 % and 110% of rated voltage
?) Documents specified in Annex C.
The type test and short-circuit withstand test report of the transformers shall be valid within ten (10)
years count from the issued date in the test reports to the bid closing date.
EM
:

• 23 -
  กาแฟหางาน.1111
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  EME
  Approved date: 17 SEP 2025
  Rev. No.:
  Form No.
  Page 23 of 51
  PEA will also accept other documents instead of the type test and short-circuit withstand test reports in
  the following conditions:
  (1) In case the proposed transformer has been supplied to PEA and get the order from PEA’s Supplies
  Planning and Procurement Department (Head office), the Purchase Order (PO) which is not more
  than three (3) years counted from the issued date of the document to the bid closing date can be
  submitted, or
  (2) In case the proposed transformer has been registered for PEA Product Acceptance",
  the valid registration certificate counted to the bid closing date can be submitted, or
  (3) In case the proposed transformer has been registered for Product Lists for transmission and substation turnkey project “, the latest PEA’s announcement of the Product Lists Registration
  counted to the bid closing date can be submitted.
  However, the document in case (1), (2) and (3) shall be proved that transformer specified in the
  Purchase Order or PEA Product Acceptance Registration Certificate or the latest PEA’s announcement
  of the Product Lists Registration shall be the same product. type/model and all ratings as the proposed
  transformer for this bid.
  The PEA’s bid committee reserves the right to request type test and short-circuit withstand test
  reports for further consideration. The bidder who cannot supply the type test and short-circuit
  withstand reports or whose supplied type test and short-circuit withstand reports do not comply
  with this specification, shall be rejected.
  Note:
  21
  PEA Product Acceptance (PPA) is the process for enhancing quality of electrical apparatus which PEA
  procures by making quality control system and certification of product’s quality by reliable Certification
  Body (CB). PPA is the responsibility of Research and Electrical Equipment Quality Control Division.
  Product Lists for transmission and substation turnkey project is the process of registration of electrical
  apparatus used in PEA’s power system. Product Lists are the responsibility of PEA’s Product Lists
  Committees.
• 24 -
  การไฟฟ้าส่วนภูมิ
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 IIz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Id.2.3 Testing laboratories
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 24 of 51
  The type test and short-circuit withstand test shall be conducted or inspected by the testing laboratories
  as follows:
  (1) Laboratorics/institutes which are members of the Short-circuit Testing Liaison (STL).
  (2) Independent laboratories/institutes which are accredited according to TIS 17025 or ISO/IEC 17025
  with the scope of accreditation covering the relevant test items, standards, and equipment.
  The bidders or manufacturers who are accredited according to TIS 17025 or ISO/IEC 17025 prefer
  to carry out the type tests and short-circuit withstand test of the transformers with the laboratories
  or by the manufacturers themselves, the tests shall be inspected by the testing laboratories as
  mentioned in (1) or (3) or (4).
  The certificate and scope of accreditation of the independent laboratories/institutes shall be
  submitted with the bid for consideration.
  (3) Thailand’s national laboratories, institutes, universities, and electric utilities, as follows:
  Electricity Generating Authority of Thailand (EGAT)
• Thonburi Electrical Power Laboratory (TEPL)
  Chulalongkorn University (CU)
  (4) Other laboratories, institutes, universities, or electric utilities approved by PEA. In this case. the
  details of the test facilities of the laboratorics shall be submitted to PEA for approval before
  proceeding with the tests and before the bid closing date. PEA reserves the right to send
  representatives to inspect and witness the tests at the cost of the bidders or manufacturers.
  Id.2.4 The information in the Test report
  EME
  PEA
  The minimum information required in the type test and short-circuit withstand test report for transformers shall include the following items:
  (1) Transformer information
  (1.1) Manufacturer’s name
  (1.2) Model
  (1.3) Manufacturer’s serial number
  (1.4) Number of phases
  (1.5) Rated voltage of the high-voltage winding
  (1.6) Rated voltage of the low-voltage winding
  (1.7) Rated voltage ratio
  (1.8) Rated frequency
  (1.9) Rated power
  !
  :
• 25 -
  moskwwnang ngen
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025
  Rev. No.:
  (1.10) Rated current of the high-voltage winding
  (1.11) Rated current of the low-voltage winding
  EME
  PEA
  Form No.
  Page 25 of 51
  (1.12) Short-circuit impedance at 75°C
  (1,13) Connection symbol
  (1.14) Cooling method
  (1.15) Total mass
  (1.16) Mass of core and winding
  (1.17) Oil quantity
  (1.18) Highest voltage for equipment applicable the high-voltage winding
  (1.19) Highest voltage for equipment applicable the low-voltage winding
  (1.20) Rated insulation level
  (1.21) Type of construction
  (1.22) High-voltage winding type and material
  (1.23) Low-voltage winding type and material
  (1.24) Cross-section of the conductor in the high-voltage winding
  (1.25) Cross-section of the conductor in the low-voltage winding
  (1.26) Number of strands per turn of high voltage winding
  (1.27) Number of strands per turn of low voltage winding
  (1.28) Number of strands radially across the layer (for all turns) of high voltage winding
  (1.29) Number of strands radially across the layer (for all turns) of low voltage winding
  (1.30) Total number of turns per phase
  (1.31) Number of turns each tap
  (2) Drawing
  (2.1) Overall dimensions of transformer
  (2.2) Tank dimension
  (2.3) Drawing of cross section area of core
  (2.4) Drawing of active part
  (2.5) Drawing which show the core and coil information according to Figure 8
• 26 -
  noslwänänu günna
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 IIz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025
  Rev. No.:
  IV 7max
  Z lower-
  Alu inner racia!
  Lv inrer vaskul
• ALE!
  egy radial under
  phù radial sath
  Core Murmeler
  HV Zmax
  LV Zmax
  LV Zmin HV Zmin
  Form No.
  Page 26 of 51
  Mincow Height
  1d.3
  Figure 8 Core and coil constructions.
  (3) Photograph of transformers
  Colour photographs, showing out-of-tank inspection, where the active part is removed from the
  tank for inspection of the core and windings, both before and after the short-circuit withstand test,
  shall be included in the short-circuit withstand test report.
  The colour photographs shall clearly show structure all side of the transformer.
  In case the information in the reports are not completed according to the above requirement, the
  bidders will be rejected.
  Acceptance test items and acceptance test procedures
  1d.3.1 Acceptance test items
  The sample of transformers shall pass the following tests in accordance with the relevant standards:
  (1) Measurement of winding resistance
  (2) Measurement of voltage ratio and check of phase displacement
  (3) Measurement of short-circuit impedance and load loss
  (4) Measurement of no-load loss and current
  (5) Applied voltage test
  (6) Induced voltage withstand test
  (7) Leak testing with pressure for liquid-immersed transformers (tightness test)
  (8) Oil dielectric breakdown voltage test
  (9) Total dry film thickness test
  EME
  (10) Temperature-rise test
  PEA
  1}
  (11) Full wave lightning impulse test
• 27 -
  mnzi wananunump
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025 Rev. No.:
  Form No.
  Page 27 of 51
  (12) Short-circuit withstand test” (only for transformers rating of 50-250 kVA)
  Note:
  The total dry film thickness shall be measured by the contractor for acceptance testing and witnessed by the
  PEA’s acceptance committee. Total dry film thickness shall not be less than 180 μm in accordance with ISO
  12944 5. PEA will randomly select the samples transformers only the first lot.
  For transformers which are out-of-tank for inspection in short-circuit withstand test, the insulating oil shall
  be dehydrated at the manufacturer’s factory and the oil dielectric breakdown voltage shall be retested. The
  report of the oil dielectric breakdown voltage test shall be submitted to PEA with shipment/delivery. for each
  ordered transformer.
  1d.3.2 Acceptance test procedures
  Test procedures for acceptance test items 1d.3.1(1) to 1d.3.1(9)
  Samples of transformers shall be selected from each delivery lot. which will be sampling from
  transformers with the same material number (same rating). Except the total dry film thickness test, will
  randomly select the samples of transformer only from the first lot.
  The sample sizes for taking item 1d.3.1(1) to 1d.3.1(9) according to Table 15.
  Table 15 Number of samples for test items 1d.3.1(1) to 1d.3.1(9)
  Number of transformers
  per delivery lot “(Unit)
  1
  2 to 15
  16
  to 25
  26
  to
  90
  91
  to
  150
  151 to
  500
  More than 500
  Sample size of transformers
  (Unit)
  1
  2
  3
  5
  8
  13
  20
  EME
  Note: Number of transformers per delivery lot classified by material number
  Test procedures for acceptance test items 1d.3.1(10) to 1d.3.1(12)
  The test items 1d.3.1(10). 1d.3.1(11) and Id.3.1(12) shall be tested on one (1) unit for each item in the first
  lot of each contract which the transformers must have passed the test items 1d.3.1(1) to 1d.3.1(9).
  Each test item shall be tested considering the total number of the transformers in the contract with the
  same material number (same rating) shown in Table 16:
• 28 -
  ก: ฟฟ้า งาน
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  EME
  PEA
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 28 of 51
  Temperature-rise
  Table 16 Number of samples for test items 1d.3.1(10), 1d.3.1(11) and 1d.3.1(12)
  Number of transformers
  per contract

Test items
Full wave lightning
Short-circuit
(Unit)
test
impulse test
withstand test
1 to 9
Not require
Not require
Not require
10 to 29
Require
Not require
Not require
30 to 189
Require
Require
Not require
190 or more
Require
Require
Require
Note:
Number of transformers per contract classified by material number
Each test item can be separately tested using different samples of the transformers, for example, if items
ld.3.1(10). ld.3.1(11). and 1d.3.1(12) are tested, 3 samples (3 serial numbers) from all samples of the
transformers can be used. The sample sizes for taking items Id.3.1(10), Id.3.1(11), and Id.3.1(12)
according to Table 17:
Table 17 Number of samples for test items 1d.3.1(10), 1d.3.1(11), and 1d.3.1(12)
Test items (1d.3.1)
(10) Temperature-rise test
Sample size of transformers (Unit)
(11) Full wave lightning impulse test
(12) Short-circuit withstand test
1
1
After the test. the transformers shall be rebuilt completely by the contractor free of charge and sent back
to PEA with the same number of samples.
PEA reserves the right to have acceptance tests according to 1d.3 Acceptance test items and
acceptance test procedures conducted by the PEA’s laboratory or by the testing laboratories, as
specified in clause (1) or (2) or (3) or (4) of 1d.2.3 Testing laboratories or by the manufacturer’s
laboratories. The transportation shall be carried out by the contractor.
PEA reserves the right to send representatives to witness the tests.
The cost of all tests and reports shall be borne by the contractor.

• 29 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568

Approved date: 17 SEP 2025 Rev. No.:
Form No.
Page 29 of 51
1e
Inspection
To ensure about the quality of transformers, PEA reserves the right to send representatives for inspection
at the following two stages:
—
At any time during receipt of raw material and during manufacture/assembly, as desired by PEA.
10

At finished stage i.c.. transformers are fully assembled and are ready for dispatch.
Packing
For transformers manufactured outside the territories of Thailand, each transformer shall be seaworthy
and packed in individual export crate or wooden case which will not be returned.
The packing details, see Annex B.
EME
PEA

• 30 -
  moskwŵnanunûn^a
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Note:
  EME
  PEA
  Approved date:
  17 SEP 2025 Rey. No.:
  |
  Conditions for documentation and consideration
  Form No.
  Page 30 of 51
  The Contractor has to supply documents in English and/or Thai: one (1) set of hard copy and one (1) set
  of soft copy (.pdf) to PEA’s acceptance committee before shipment/delivery of each lot of transformers
  as follows:
  (1) Routine test reports
  (2) Complete installation, operation, and maintenance instructions
  (3) Complete part lists
  (4) Number of turns of each winding, cach coil, and each tapping position
  (5) Mass of HV windings and of LV windings
  (6) Type of enamel, temperature class. and size of the enameled wire
  (7) Information for Reference (only one (1) unit per contract). The following information for cach
  transformer shall be submitted for maintenance purpose.
  Coil height for each winding before assembly and after complete assembly.
  Torque value on clamping bolts or pressure for each winding before assembly and after
  complete assembly.
  Photograph of each coil for each phase and photograph of core and coils assembly. The
  photograph of each coil shall be taken from the final production process before placing to
  the core, top view and front view shall be provided. The photograph of core and coils assembly shall be taken just prior to place the completed core and coils assembly into the
  tank. top view, front view, right view, left view and rear view shall be provided for complete
  set of photographs. All photographs shall be 216 mm (8-1/2 in) by 280 mm
  (11 in) gloss prints properly labeled relevant to the view taken.
  (8) Invoice and Test report of the following material and accessories used in each supply shall be
  submitted.

Transformer oil
Silicon steel
· Copper conductor
Insulation paper and pressboard
Pressure relief
Gaskets

Bushing

• 31 -
  การไฟฟ้าส่วนภูมิภา
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 IIz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  C2
  Critical documents of the proposed transformers
  Form No.
  Page 31 of 51
  The bidder shall submit the critical documents in table below with the bid. The proposal without
  critical documents will be rejected.
  The bidder shall fill data in the table below and shall submit with the bid.
  Sheet 1/4
  No.
  Critical documents
  Proposed technical
  Reference document
  document
  (Page/Item)
  1
  Thai Industrial Standard Institute (TISI) certification
  Yes
  No
  in according to TIS 384 Part 1. as mention in 1b (See
  Page 1 of 51)
  2
  Dry film thickness test report, as mention in 1c.5.3 (See
  Page 9 to 12 of 51)
  Yes
  No
  The dry film thickness test report shall be submitted only
  one (1) unit of each rating.
  دیا
  3
  HV and LV Bushing test report, as mention in 1c.8 (See
  Page 13 to 14 of 51)
  Yes
  No
  4
  Certification and scope of accreditation of the
  Yes
  No
  manufacturer’s laboratories, as mention in 1d.1 (See
  Page 20 of 51)
  5
  Type test and Short-circuit withstand test report, as
  mention in 1d.2 (See Page 20 to 27 of 51)
  (1) For transformers with rating of 50 250 kVA (See
  Page 22 of 51)
  Yes
  No
  EME
  PEA
  Type test and short-circuit withstand test reports of
  transformers identical to the proposed transformer, or
  (2) For transformers with ratings of more than 250 kVA
  CASE 1: (See Page 22 of 51)
  Yes
  No
  The type test and short-circuit withstand test reports
  of the transformers identical to the proposed
  transformer, or
• 32 -
  การไฟฟ้าส่วนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PIIASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  No.
  Approved date: 1 SEP 2025
  Rev. No.:
  Critical documents
  Form No.
  Page 32 of 51
  Sheet 2/4
  Proposed technical
  Reference document
  document
  (Page/Item)
  CASE 2: (See Page 22 of 51)

1. The type test report of transformers identical to the
   Ycs
   No
   proposed transformer of three (3) items as follows:

• Temperature-rise test
  Full wave lightning impulse test
  Measurement of no-load loss and current at
  90% and 10% of rated voltage

2. Documents specified in Annex C (See Page 47 to
   51 of 51)
   Yes
   No
   The copy previous Purchase Order (PO), as mention in
   1d.2.2 (See Page 23 of 51), or
   Yes
   No
   PEA Product Acceptance Registration Certificate, as mention in 1d.2.2 (See Page 23 of 51), or
   Yes
   No
   6
   The latest PEA’s announcement of the Product Lists
   Registration, as mention in 1d.2.2 (See Page 23 of 51) Testing laboratorics, as mention in 1d.2.3 (See Page 24
   of 51)
   Yes
   No
   Yes
   No
   EME
   i
   Yes
   No
   arc
   (1) Laboratories/institutes which are members of the
   Short-circuit Testing Liaison (STL), or (2) Independent laboratorics/institutes which
   accredited according to TIS 17025 or ISO/IEC 17025
   with the certificates and scope of accreditation
   covering the relevant test items, standards, and
   equipment, or
   (3) Thailand’s national laboratories, institutes,
   universities, and electric utilities, as follows:
   Yes
   No

• Electricity Generating Authority of Thailand (EGAT)
• Thonburi Electrical Power Laboratory (TFPL)
• Chulalongkorn University (CU), or
  (4) Other laboratories, institutes, universities, or electric
  utilities approved by PEA.
  Yes
  No
• 33 -
  การไฟฟ้าสวย ราค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025 Rev. No.:
  Form No.
  Page 33 of 51
  Sheet 3/4
  No.
  Critical documents
  Proposed technical
  Reference document
  7
  Packing detail(s), as mention in If (See Page 29 of 51),
  and ANNEX B (See Page 45 to 46 of 51)
  document
  Yes
  (Page/Item)
  No
  Packing method (shown by drawing(s), and describe packing materials)
  Number of transformers in one (1) crate or wooden casc
  Overall dimensions (L x W x H) of cach crate or
  wooden case in cm
  Volume of each crate or wooden case in m’
  Gross weight of each crate or wooden case in kg

Number of crates or wooden cases

Details of the wood treatment, name and composition
of preservatives
8
Design data and guarantee for the proposed transformers
(See Page 35 to 41 of 51)
Yes
No
9
Drawing of overall transformers and inside tank with
Yes
No
dimensions in mm showing of particulars of normal
construction details
10
Drawings, with dimensions in mm, of the accessories:
Yes
No

1. HV and LV bushings
2. Terminal connectors, on IIV and LV bushings, with
   description of materials used for the component parts
3. Nameplate with connection diagram
4. Valve, showing the internal construction
5. Earthing terminal connector
6. Bracket for surge arrester
7. Earthing terminal for surge arrester
8. Lifting lug
9. Lifting eye
10. Pressure relief valve
11. Thermometer pocket
12. Oil level gauge
13. Oil filling plug
    EME
14. Supporting lugs
15. Compression type of cable lug

• 34 -
  การไฟฟ้าส่วนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  No.
  11
  Approved date:
  17 SEP 2025
  Rev. No.:
  Critical documents

16. Sludge drain plug
17. Off load tap changer
18. Bird guard
19. Dehydrating breather, and details of coupling (if any)
20. Dial type thermometer with adjustable contact(s) (if any) 21) Double float Buchholz relay having two (2) contacts
    (for alarm and tripping) (if any)
21. Accessorics according to manufacturer’s design (if any) Catalogues with details of the accessories:
22. Pressure-relief valve
23. Core
24. HV and LV Winding
25. Off load tap changer
26. Insulation paper
27. Gaskets
28. Oil drain valve
29. Accessories according to manufacturer’s design (if any)
    12
    Drawing of core and coil construction
    13
    Specifications of transformer oil and test report
    EME
    PEA
    Form No.
    Page 34 of 51
    Sheet 4/4
    Proposed technical
    Reference document
    document
    (Page/Item)
    Yes
    No
    Yes
    No
    Yes
    No

• 35 -
  การไฟฟ้าส่วนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  й
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจพ1-มป-010-2569
  Form No.
  Page 35 of 51
  Design data and guarantee for the proposed transformers shall be submitted with the bid.
  PEA Material No
  Sheet 1/7
  Characteristics and Rating
  Manufacturer’s name and
  country of origin
  Турс
  Model’s name
  Applicd standard
  Rated power
  Unit
  PEA’s requirement
  Oil-immersed
  According to 1b Standards
  KVA
  See C3 Schedule of detailed
  requirement
  Rated frequency
  Rated primary voltage
  Rated secondary voltage
  Connection symbol
  Hz
  50
  V
  22000 or 33000
  V
  416/240
  Dynll
  Type of oil preservation system
  C3 Schedule of detailed
  requirement
  Operation duty: continuous operation (Type DB)
  Yes/No
  Yes
  Temperature rise of top oil
  K
  Not more than 50
  Temperature rise of winding (at full load)
  K
  Not more than 55
  Primary tapping: off-circuit condition
  Yes/No
  Number of tapping positions
  Yes
  5
  Percent of rated voltage of cach tapping
  0%
  1-2 × 2.5% of primary voltage
  No-load current & Tolerance
  %&%
  Short-circuit impedance at 75°C & Tolerance
  % & %
  See Table 2 Losses and
  short circuit impedance
  Losses, for each transformer unit
• No-load loss plus positive tolerance
  W
  See Table 2 Losses and
• Load loss, plus positive tolerance, at 75°C
  W
  short circuit impedance
  EME
  PEA
  Proposed data
• 36 -
  การไฟฟ้าส่วนภูมิ
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025
  Rev. No.:
  ประกวดราคาอิเล็กทรอนิกส เลขที่ กจ 1-มป-010-2569
  Characteristics and Rating
  Efficiency in %, at 75°C and at load:
  Form No.
  Page 36 of 51
  Sheet 2/7
  PEA Material No
  Unit
  PEA’s requirement

1/2 of rated power and P.F. = 1.0
001

I of rated power and P.F.

1.0
%
%
Voltage regulation at P.F. = 1.0
HV Bushings

• Manufacturer’s name and
  Country of origin
• Type or Model
• Applied standard
• Rated current
• Full-wave impulse withstand voltage, or BIL
  A
  kV, peak
• Low-frequency dry 1-minute test voltage
  kV, r.m.s.
  —
  Low-frequency wet 10-second test voltage
  kV, r.m.s.
  Material of insulator
• Colour of glazing
  Stud thread size, Metric
  LV Bushings
• Manufacturer’s name and
  Country of origin
• Type or Model
• Applied standard

Rated current

• Full-wave impulse withstand voltage, or BIL
  Low-frequency dry 1-minute test voltage
• Low-frequency wet 10-second test voltage
  -Material of insulator
  EMEolour of glazing
  PEA
  A
  DIN EN 50180
  125 (for system voltage 22 kV)
  170 (for system voltage 33 kV)
  55 (for system voltage 22 kV)
  77 (for system voltage 33 kV)
  50 (for system voltage 22 kV)
  70 (for system voltage 33 kV)
  Porcelain
  Brown
  DIN 42539
  See Table 10 Current rating
  of LV Bushing
  kV, peak
  30
  kV. r.m.s.
  10
  kV, r.m.s.
  10
  Porcelain
  Brown
  Proposed data
• 37 -
  การไฟฟ้าส่วนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 KV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจ 1-มป-010-2569
  Form No.
  Page 37 of 51
  Sheet 3/7
  PEA Material No…….
  Unit
  PEA’s requirement
  Proposed data
  Characteristics and Rating
  LV Bushings
• Stud thread size, Metric
• Secondary neutral point is loaded with rated
  Yes/No
  Yes
  current
  Terminal connectors on HV bushings
  · Manufacturer’s name and
  country of origin

For aluminium conductor diameter range
mm
—
7.5 12.6
Terminal connectors on LV bushings

• Manufacturer’s name and
  country of origin

Terminal pads are according to PEA’s Yes/No
Yes
Drawing No. SB4-015/68001
HV Winding

• Manufacturer’s name and Country of origin
  (the bidders have to quote not more than
  three (3) manufacturers)

Material

• Type of enamel or insulating material of wire

Size of wire

• Diameter

Cross section area

• Resistance per phase at 75°C

Full-wave lightning impulse test voltage
min
mm2
Copper
Ohm
kV, peak
A/mm2
125 (for system voltage 22 kV)
170 (for systein voltage 33 kV)
50 (for system voltage 22 kV)
70 (for system voltage 33 kV)

• Power-frequency test voltage, 1 min
  kV, r.m.s.
• Construction of winding
  Current density
  Number of layers per coil
  EME
• Number of turns of each coil in tap No.3 PEA
  Turns
• 38 -
  การไฟฟ้าส่วนภูมิภา
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025
  Kev, No.:
  Form No.
  Page 38 of 51
  Sheet 4/7
  PEA Material No
  Unit
  PEA’s requirement
  Proposed data
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจพ1-มป-010-2569
  Characteristics and Rating
  HV Winding
• Number of turns of each tapping position
  Turns
• Total turns of each coil
  Turns
  LV Winding
  Manufacturer’s name and Country of origin
  (the bidders have to quote not more than
  three (3) manufacturers)
• Material
• Type of enamel or insulating material of wire
• Size of wire
• Dimension
• Cross section arca
• Resistance per phase at 75°C
• Full-wave lightning impulse test voltage
• Power-frequency test voltage, I min
• Construction of winding

Current density

• Number of layers per coil

Total turns of cach coil
Core
mm × mm
mm2
Ohm
Copper
kV, pcak
30
kV, r.m.s.
10
A/mm2
Turns

• Manufacturer’s name and Country of origin
  (the bidders have to quote not more than
  three (3) manufacturers)
• Construction of Core
  Pressure relief valve
• Manufacturer’s name and
  Country of Origin
• Type or model
  Operating pressure
  EME
  Flow rate at…… kg/cm2
  kg/cm2
  cc/sec
  PEA
• 39 -
  การไฟฟ้าส่วนภูมิภาค
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025 Rev. No.:
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจ 1-มป-010-2569
  Characteristics and Rating
  Form No.
  Page 39 of 51
  Sheet 5/7
  PEA Material No
  Unit
  PEA’s requirement
  Completely assembled transformer shall
  kg/cm2
  withstand, without permanent deformation, a
  maximum pressure of
  Method of cooling
  ONAN
  m2
  Total cooling surface
  Transformer oit
• Manufacturer’s name and
  Country of Origin
• Type or Model
• Standard
  Mass
• Quantity of oil filling
  liters
  IEC 60296
• Mass of core
  kg

Mass of winding
kg

• Mass of the part liftable from tank
  kg
• Mass of transformers, including oil and
  kg
  Not more than 1,000 (for 50-160 kVA)
  Not more than 1,200 (for 250 kVA)
  accessories
  Tank Thickness
• Thickness of side wall
  min
• Thickness of top plate
  mm
• Thickness of bottom plate
  mm
  Internal Tank dimensions
• Height

· Width
Inm

• Depth
  mm
  Overall Dimensions
• Overall height
  mm
• Overall width
  mi
  EME
  Overall depth
  mm
  Height over cover
  mm
  PEA
  Proposed data
• 40 -
  การไฟฟ้าส่วนรา
  .:
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 40 of 51
  Sheet 6/7
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจ 1-มป-010-2569
  PEA Material No…….
  Characteristics and Rating
  Unit
  PEA’s requirement
  Proposed data
  Requirement of tank dimension
• The distance between the upper supporting
  mm
  lug and the bottom lug.
• The distance between the edge of bolt slot of
  the bottom supporting lug and the bottom of
  the transformer tank.
  mm
  See Table 6 Dimensional
• The distance between the tank cover (Top
  plate) and fins for installing earthing
  terminal of surge arrester.
  mm
  requirements for the pole-
  mounted installation
• The distance between hole of the mounting
  mm
  bracket for installing surge arrester and slud
  of HV bushing.

The distance between the LV terminal
min
connector and the supporting lugs.
Fin dimensions
Fin radiators or Corrugated thickness
mm
Dimension of each fin (LxBxT)
min
Number of Fins per radiator

Side of tank

Front of tank

• Total number of fins
  Terminal markings and connections conform
  to PEA’s requirement
  Tank finish
• Colour of tank
  Yes/No
  Yes
  RAL 7036
• Total dry film thickness
  μη
  Not less than 180

Tank finish conforms to PEA’s requirement
Yes/No
Ycs
EME
PEA
EME
PEA

• 41 -
  unskalūnāmu yüme
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  1” SEP 2025
  Rev. No.:
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจพ1-มป-010-2569
  Characteristics and Rating
  Bushing clearance (Please fill in the shortest
  of clearance)
• LV to carth
• Between LV bushings
• HV to carth
  3
  Between HV bushing
  X/R ratio
  Rated dynamic short circuit current and
  withstanding duration
• Current (I)
  Form No.
  Page 41 of 51
  PEA Material No
  Unit
  PEA’s requirement
  Proposed data
  min
  mm
  mm
  Not less than 225 (for 22 kV system)
  Not less than 320 (for 33 kV system)
  Not less than 225 (for 22 kV system)
  1212
  Not less than 320 (for 33 kV system)
  kA, peak
  Duration
  Duration of overload
  -25% overload
  minutes
• 50% overload
  minutes
  Magnetic flux density
  Tesla
  1
  Sheet 7/7
• 42 -
  analwinan uglarp
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date:
  17 SEP 2025
  Rev. No.:
  Annex A
  PEA’s code number marking
  Form No.
  I
  Page 42 of 51
  The contractor shall paint the PEA’s code number on the transformer with the following requirements:
  (1) The letter and Number shall be used STENCIL font.
  (2) The PEA’s code number shall be painted in orange.
  (3) The height of the letter and number shall not be less than 3 inches.
  (4) The position of the PEA’s code number of transformers shall be painted according to Table A:
  Table A The position of the PEA’s code number of transformers
  No. Types of transformers
  Hermetically Sealed type
  with one
  front-mounted fin
  Painting position of PEA’s code number
  Located on the lower front side of the transformer tank or
  O
  EME
  PLA
  Located on the side of the transformer tank.
• 43 -
• ฟ า า ก ม
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  No.
  Types of transformers
  2
  Hermetically Sealed type
  with three
  sidc-mounted fins
  EME
  PEA
  Form No.
  Page 43 of 51
  Painting position of PEA’s code number
  OF
  Located on the lower front of the transformer’s tank or
  Located on the side of the fin (design 1) ør
  10
  Located on the side of the fin (design 2)
• 44 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  No. Types of transformers
  السلام
  3
  Approved date:
  17 SEP 2025 │▪
  Rev, No.:
  Hermetically Sealed type
  (3D)
  Conservator Type
  Form No.
  Page 44 of 51
  Painting position of PEA’s code number
  Located on the side and the front of the fin.
  Located on the lower front of the transformer’s tank
  and conservator tank
  Note
  In case the painting position of the PEA’s code number is not possible at the required position. The contractor
  shall contact the Distribution Transformer Management Division to determine an appropriate painting position.
  EME
  PEA
• 45 -
  nnstwwnanu günne
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025
  Rev. No.:
  !
  Form No.
  Page 45 of 51
  Annex B
  Packing Details
  The transformers that are packed in individual crate or wooden case shall comply with the following
  requirements:
  (1) The minimum clearance between the crate or wooden case and the transformer shall be not more than
  five (5) cm.
  (2) Specify the design for constructing the crate for the transformer on the sides and front according to the
  Figure B.1.
  Left
  AÐA
  А
  Front
  T
  Right
  Back
  Figure B.1 Wooden crate construction design
  (3) The crate or wooden case shall be designed to be movable by a forklift truck in such a manner that truck’s
  forks can be inserted at the width side or long side of the bottom of the case, shown in Figure B.2.
  EME
  PEA
  Insert truck’s fork
  Insert truck’s fork
  Figure B.2 The wooden case designed for moving by forklift
• 46 -
  การไฟฟ้าส่วนภูมิการ
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 Rev. No.:
  Form No.
  Page 46 of 51
  (4) The wooden parts shall be treated with waterborne wood preservatives. The wood preservatives used
  shall not contain Arsenate (As,O) as a component.
  (5) The crate or wooden case containing the transformers shall be designed to be strong enough to support at
  least one additional crate or wooden case stacked on top.
  (6) The bidder shall attach waterproof labels size 210 (width) x 297 (length) mm on both the front and back
  sides of the crate or wooden case. The label shall include the following minimum information:
  (1) Manufacturer’s name or Distributor’s name
  (2) Brand name or Trademark
  (3) Contract number
  (4) PO number
  (5) Delivery lot number
  (6) Crate or wooden case number
  (7) PEA number
  The packing details of the proposed transformers shall be submitted with the bid, as follows:
  (1) Packing method (shown by drawing(s), and describe packing materials)
  (2) Number of transformers in one (1) crate or wooden case
  (3) Overall dimensions (I. x W x H) of each crate or wooden case in em
  (4) Volume of each crate or wooden case in mi
  (5) Gross weight of each crate or wooden case in kg
  (6) Number of crates or wooden cases
  (7) Details of the wood treatment, name and composition of preservatives
  EME
  PEA
• 47 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  EME
  PEA
  Approved date: 17 SEP 2025 Rev, No.:
  Form No.
  Page 47 of 51
  Annex C
  Comparison Method
  A transformer is considered similar to another transformer taken as a reference if it has the following
  characteristics in common with the latter:
  (1) Same type of operation, for example generator step-up unit, distribution, interconnection transformer and
  same rated voltage according to Table C.1;
  (2) Same conceptual design, for example dry-typc. oil-immersed type, core type with concentric windings.
  sandwich type, shell type, circular coils. non-circular coils;
  (3) Same arrangement and geometrical sequence of the main windings;
  (4) Same type of winding conductors, for example, aluminium, aluminium alloy, annealed or hardened copper,
  metal foil, wire, flat conductor, continuously transposed conductors and epoxy bonding. if used:
  (5) Same type of main windings for example, helical, disc-, layer-type, pancake coils;
  (6) Absorbed power at short circuit (rated power/per unit short-circuit impedance) between 30% and 130% of
  that relating to the reference unit, see Table C.2:
  (7) Axial forces. radial forces, axial winding stresses and radial winding stresses occurring at short circuit not
  exceeding 120% of those in the reference unit. (Force shall be calculated by Finite element program such
  as FLD12 etc.. Iland calculation shall be rejected)
  (8) Same manufacturing processes:
  (9) Same clamping and winding support arrangement.
• 48 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025 | Rev. No.:
  T
  Form No.
  Page 48 of 51
  Critical documents for comparison method
  EME
  PEA
  In case the ability to withstand the dynamic short circuit is demonstrated by comparison between the reference
  transformer and proposed transformer, the bidder shall submit documents as following with the bid:
  (1) Type test and short-circuit withstand test of the reference transformer, which test procedure shall be
  according to 1d.2.1.
  (2) Calculation of thermal ability to withstand short circuit of the proposed transformer.
  (3) Calculation report of short circuit force and stress which using Finite Element Method (FEM) software of the reference transformer and the proposed transformer. The calculation report shall give evidence the force
  and stress according to item (7) as mentioned above.
  (4) Core and coil construction of the reference transformers and the proposed transformers which shall include
  details at least as shown in Figure C.1.
  LV Zmax
  Z lower
  winner racial
  1- one’
  Por facal Voir
  Window Height
  HV Zmax
  LV 7max-
  LV Zmin

HV Zmin
Figure C.1 Core and coil construction
(5) Information according to Table C.3. which the bidder shall fill in all the information in the table completely.

• 49 -
  การไฟฟ้า จน ก
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  EME
  PEA
  Approved date:
  17 SEP 2025 Rev. No.:
  Table C.1
  Form No.
  Page 49 of 51
  Type of operation and rated voltage of the proposed transformers similar to the reference transformers
  Type and Rated voltage
  Type
  Rated primary voltage
  Rated primary voltage
  Rated secondary voltage (3 phase)
  The reference transformer
  3 Phase only
  22 kV
  33 kV
  416/240 V
  The proposed transformers
  3 Phase
  22 kV
  33 kV
  416/240 V
  Table C.2
  Rated power of the proposed transformers similar to the reference transformers
  Rated power (kVA) of
  the reference
  transformers
  Rated power (kVA) of the proposed transformers
  1
  250
  315
  500"11
  2
  315
  315
  400
  500""
  درا
  3
  400
  315
  400
  500’
  4
  500"
  315
  400
  500"
  5
  630
  315
  400
  500"
  630 800
  1.000
  6
  800
  315
  400
  500"
  630 800
  7
  1,000
  315
  400
  500’
  630 800
  1,000 1.250
  1,000
  1,250
  00
  8
  1,250
  315
  400
  500’
  9
  1.500
  315 400
  500"
  10
  2.000
  400
  630
  630 800
  630 800
  800
  1,000 1.250
  1.500
  1,000 1.250 1.500
  1,000 1.250 1.500 2.000
  Note:
  Based on 6.5% short-circuit impedance. In case the impedance of 500 kVA transformer more than 6.5%, the bidders
  shall recalculate this table for PEA approval.
• 50 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025
  Rev. No.:
  Table C.3
  Form No.
  Page 50 of 51
  Comparison of reference transformers and proposed transformers
  Design value of
  Description
  Rating (kVA)
  % Short circuit impedance
  Construction of Core
  Type of HV winding conductors
  (e.g. annealed or hardened copper, foil,
  rectangular, round wire)
  Type of LV Windings conductors
  (e.g. annealed or hardened copper, foil.
  rectangular, round wire)
  Construction of IIV Windings
  (e.g. layer, disc)
  Construction of L.V Windings
  (e.g. layer, disc)
  Design value of
  the reference transformers
  the proposed transformers
  HV Current density
  (please enclosed the calculation sheet)
  Document number:
  Document number:
  LV Current density
  (please enclosed the calculation sheet)
  Document number:
  Document number:
  Axial force
  HV
  LV
  HV
  LV
  (please enclosed software calculation sheet)
  Document number:
  Document number:
  Axial stress
  HV
  LV
  HV
  LV
  (please enclosed software calculation sheet)
  Document number:
  Document number:
  EME
  PEA
• 51 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  EME
  PEA
  Approved date:
  17 SEP 2025
  Rev. No.:
  Description
  Radial force
  (please enclosed software calculation sheet)
  Form No.
  Page 51 of 51
  Design value of
  Design value of
  the reference transformers
  HV
  LV
  the proposed transformers
  HV
  LV
  Document number:
  Document number:
  Radial stress
  HV
  LV
  HV
  LV
  (please enclosed software calculation sheet)
  Document number:
  Document number:
  Same arrangement of main windings and
  geometrical sequence as the reference unit
  (Yes/No)
  Document number:
  (please enclosed the winding detail drawing)
  Same clamping and supporting arrangement.
  (Yes/No)
  (please enclosed the clamping detail drawing) Document number:
  Yes
  No
  Yes
  No
• 52 -
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS
  WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  Specification No. RTRN-035/2568
  Approved date: 17 SEP 2025
  Rev. No.: 0
  Form No.
  Page 1 of 1
  เอกสารเพิ่มเติมแนบรายละเอียดสเปค
  (ADDENDUM)
  เอกสารเพิ่มเติม (ADDENDUM) นี้ให้ถือเป็นส่วนหนึ่งของรายละเอียดสเปคเลขที่ RTRN-035/2568 THREE
  PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION SYSTEMS WITH ABILITY TO
  WITHSTAND SHORT CIRCUIT
  การยื่นเอกสารรายงานผลการทดสอบ Type test and Short-circuit withstand test ตามหัวข้อ 1d.2.2
  กฟภ. ยอมรับให้ใช้รายงานผลการทดสอบ Type test and Short-circuit withstand test ตามสเปคอ้างอิงเลขที่ RTRN-035/2561 ผู้ยื่นข้อเสนอสามารถยื่นรายงานผลการทดสอบ ดังกล่าวได้จนถึง วันที่ 1 มกราคม พ.ศ. 2571 ตามเงื่อนไข ดังต่อไปนี้
  (1) หม้อแปลงขนาดพิกัด 50 - 2,000 kVA โดยการทดสอบ ผู้ยื่นข้อเสนอต้องยื่นเอกสารในวันที่เสนอราคา ดังนี้
  (1.1) รายงานผลการทดสอบ Type test and Short-circuit withstand test ตามสเปคอ้างอิงเลขที่
  RTRN-035/2561 ของหม้อแปลงที่มีพิกัดเดียวกับหม้อแปลงที่เสนอ
  (1.2)
  (1.3)
  เอกสารการค้านวณเทียบระหว่างหม้อแปลงที่เสนอ และหม้อแปลงที่ผ่านการทดสอบตามข้อ (1.1) ตามที่ระบุใน Annex C (Page 47 to 51 of 51)
  รายงานผลการทดสอบหัวข้อ Full Wave Lightning Impulse ของหม้อแปลงพิกัดที่เสนอ ที่ออกแบบ และผลิตตามสเปคอ้างอิงเลขที่ RTRN-035/2568 ซึ่งรายงานผลการทดสอบดังกล่าว ต้องออกโดย ห้องทดสอบที่ กฟภ. ยอมรับ ตามที่ระบุไว้ในหัวข้อ 1d.2.3 Testing laboratories
  (2) หม้อแปลงขนาดพิกัด 315 – 2,000 kVA โดยการเปรียบเทียบ ผู้ยื่นข้อเสนอต้องยื่นเอกสารในวันที่เสนอราคา ดังนี้ รายงานผลการทดสอบ Type test and Short-circuit withstand test ตามสเปคอ้างอิงเลขที่ RTRN-035/2561 ของหม้อแปลงอ้างอิง
  EME
  (2.1)
  (2.2) เอกสารการคํานวณเทียบระหว่างหม้อแปลงที่เสนอ และหม้อแปลงที่ผ่านการทดสอบตามข้อ (2.1)
  ตามที่ระบุใน Annex C (Page 47 to 51 of 51)
  (2.3)
  PEA
  (2.4)
  รายงานผลการทดสอบ Temperature rise และ Measurement of no load loss and current at 90% and 110% of rated voltage ตามสเปคอ้างอิงเลขที่ RTRN-035/2561 หรือ ตามสเปค อ้างอิงเลขที่ RTRN-035/2568 ของหม้อแปลงพิกัดที่เสนอ
  รายงานผลการทดสอบหัวข้อ Full Wave Lightning impulse ของหม้อแปลงพิกัดที่เสนอ ที่ออกแบบ และผลิตตามสเปคอ้างอิงเลขที่ RTRN-035/2568 ซึ่งรายงานผลการทดสอบดังกล่าว ต้องออกโดย ห้องทดสอบที่ กฟภ. ยอมรับ ตามที่ระบุไว้ในหัวข้อ 1d.2.3 Testing laboratories
• 53 -
  การไฟฟ้าส่วนภูมิภาค
  SSCOLA FLFCOY ale!
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  DISTRIBUTION TRANSFORMERS
  Specification No.

Approved date:
24 MAR 2026
Rev. No.: 0
Page 1 of 1
เอกสารเพิ่มเติมแนบรายละเอียดสเปค
(ADDENDUM)
เอกสารเพิ่มเติมแนบรายละเอียดสเปค (ADDENDUM) นี้ ให้ถือเป็นส่วนหนึ่งของรายละเอียดสเปค หม้อแปลงไฟฟ้าระบบจําหน่าย (DISTRIBUTION TRANSFORMERS) ดังต่อไปนี้
ท
1
2
3
รายการ
สเปคอ้างอิงเลขที
SINGLE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION | RTRN-047/2568
SYSTEMS WITH ABILITY TO WITHSTAND SHORT CIRCUIT
THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION RTRN-035/2568
SYSTEMS WITH ABILITY TO WITHSTAND SHORT CIRCUIT
DISTRIBUTION TRANSFORMERS WITH SENSORS FOR USING [OT
RTRN-051/2568
ยกเลิกการกําหนดหัวข้อการทดสอบเพื่อการตรวจรับตามที่ระบุไว้ในข้อ 14.3.1 Acceptance test items
จํานวน 3 หัวข้อ ดังนี้

• Mcasurement of winding resistance,
• Measurement of voltage ratio and check of phase displacement
• Leak testing with pressure for liquid-immersed transformers (tightness test)
  EME
  PEA
• 54 -
  Page 1 of 1
  การไฟฟ้าส่วนภูมิภาค
  MOMIGA, ELECTRICITY NUTHENT
  PROVINCIAL ELECTRICITY AUTHORITY
  ELECTRICAL AND MECHANICAL ENGINEERING DIVISION
  Spcification No. RTRN-035/2568: THREE-PHASE TRANSFORMERS FOR 22 kV AND 33 kV 50 Hz DISTRIBUTION
  SYSTEMS WITH ABILITY TO WITHSTAND SHORT CIRCUIT
  C3 Schedule of detailed requirement
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจพ1-มป-010-2569
  PEA
  Item
  Material
  Quantity
  No.
  1
  1050010144
  Desciption
  23 sets 500 kVA, three-phase transformer, permanently sealed and completely oil filled
  system (without gas cushion) type, withstand short-circuit, 33,000-416/240V,
  symbol Dyn11.
  1000 kVA, three-phase transformer, conservator system type, withstand short-
  circuit, 33,000-416/240V, symbol Dyn11.
  2
  1050010147
  4 sets
  ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจ 1-มป-010-2569 Specification No. RTRN-035/2568
  C3 Schedule of detailed requirement
• 55 -
  Item
  PEA
  Material Quantity
  No.
  หมายเหตุ
  Description

1. Enclosed Drawings No. SB4-015/68001
2. ผลิตภัณฑ์ที่เสนอต้องผลิตจากโรงงานที่ได้รับการรับรองระบบคุณภาพของ
   กระบวนการผลิตตามมาตรฐาน ISO 9001
3. ผลิตภัณฑ์ที่เสนอจะต้องเป็นผลิตภัณฑ์ที่ได้รับใบอนุญาตแสดงเครื่องหมาย
   มาตรฐานผลิตภัณฑ์อุตสาหกรรม (มอก.) เท่านั้น
4. ผลิตภัณฑ์ที่เสนอต้องเป็นผลิตภัณฑ์ที่ผลิตจากโรงงานที่ได้รับการรับรอง
   ความสามารถห้องปฏิบัติการทดสอบ มาตรฐาน มอก. 17025 หรือ ISO/IEC 17025 ครอบคลุมทุกหัวข้อการทดสอบประจําตามที่สเปคการไฟฟ้า ส่วนภูมิภาคกําหนด
5. การไฟฟ้าส่วนภูมิภาคจะจัดซื้อพัสดุที่ผลิตภายในประเทศ
6. บริษัทผู้ผลิตที่ได้รับการสั่งซื้อต้องส่งแผนการผลิตหม้อแปลงมาให้ การไฟฟ้าส่วน ภูมิภาค (กองจัดหาพัสดุ 1 และ กองบริหารจัดการหม้อแปลงระบบจําหน่าย) ภายใน 7 วัน นับถัดจากวันที่ได้รับหนังสือแจ้งลงนามในสัญญา/ใบสั่งซื้อ เพื่อให้
   คณะกรรมการตรวจสอบการผลิตและทดสอบ เข้าทําการตรวจสอบตามเงื่อนไข การจัดซื้อหม้อแปลงไฟฟ้าระบบจําหน่ายที่ผลิตภายในประเทศ
7. บริษัทผู้ผลิตที่ได้รับการสั่งซื้อหม้อแปลงไฟฟ้าต้องระบุน้ําหนักสุทธิ (Net Weight)
   ของหม้อแปลง ลงบนหม้อแปลงของแต่ละเครื่องบน Name Plate 8. คู่สัญญาจะต้องเป็นผู้รับผิดชอบค่าใช้จ่ายทั้งหมดในการทดสอบเพื่อการตรวจรับ (Acceptance Test) ตามข้อ 1d.3.1 ทั้งนี้ การทดสอบเพื่อประกอบการตรวจรับ หม้อแปลงไฟฟ้าในระบบจําหน่าย ณ โรงงานผู้ผลิต ให้คณะกรรมการตรวจรับ สามารถพิจารณาตรวจรับหม้อแปลงไฟฟ้า ณ โรงงานผู้ผลิตเพื่อเป็นทางเลือก นอกเหนือจากการส่งทดสอบที่ กองทดสอบอุปกรณ์ไฟฟ้า โดยให้คณะกรรมการ ตรวจรับร่วมกับคณะกรรมการตรวจสอบการผลิตและทดสอบ (ถ้ามี) และ กอง ทดสอบอุปกรณ์ไฟฟ้า สุ่มตัวอย่างและร่วมทําการทดสอบเพื่อการตรวจรับ ณ
   โรงงานผู้ผลิตโดยวิธีการทดสอบจะต้องเป็นไปตามมาตรฐานและวิธีปฏิบัติของ การไฟฟ้าส่วนภูมิภาค โดยให้คู่สัญญา เป็นผู้รับผิดชอบค่าใช้จ่ายในการทดสอบ ทั้งหมด
8. การเรียกเก็บค่าบริการทดสอบ เป็นไปตามเงื่อนไขการเรียกเก็บค่าบริการ
   ทดสอบประกอบการจัดซื้อพัสดุ ตามเอกสารแนบท้าย
   ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจ 1-มป-010-2569
   Specification No. RTRN-035/2568
   C3 Schedule of detailed requirement

• 56 -
  PEA
  Item Material Quantity
  No.
  Description

10. กรณีหม้อแปลงไฟฟ้าชํารุดระหว่างการใช้งานและอยู่ภายในระยะรับประกัน การไฟฟ้าส่วนภูมิภาค ขอสงวนสิทธิในการผ่าพิสูจน์หม้อแปลงไฟฟ้า เพื่อหา สาเหตุการชํารุด ตามเอกสารแนบท้าย 11. หม้อแปลงไฟฟ้าที่จัดซื้อในครั้งนี้ การไฟฟ้าส่วนภูมิภาคจะนําไปใช้งานทั่วประเทศ (12 การไฟฟ้าเขต) ในกรณีที่หม้อแปลงไฟฟ้าเกิดชํารุดระหว่างการใช้งานและอยู่ ในระยะเวลารับประกันคุณภาพ การไฟฟ้าส่วนภูมิภาคจะเป็นผู้รวบรวมนําหม้อ แปลงไฟฟ้าชํารุดจากคุณภาพไปจัดเก็บ ณ การไฟฟ้าส่วนภูมิภาค ทั้ง 12 เขต ตาม พื้นที่ที่ติดตั้งใช้งาน การไฟฟ้าส่วนภูมิภาคจะแจ้งให้คู่สัญญาต้องรับกลับไป ดําเนินการแก้ไขให้ถูกต้องเรียบร้อย ภายใน 30 วัน ตามข้อกําหนดในสัญญา และ หากมีค่าบริการทดสอบเพิ่มเติมให้เป็นไปตามเงื่อนไขการเรียกเก็บค่าบริการ
    ทดสอบการจัดซื้อพัสดุ ข้อ 9
11. การจัดซื้อในครั้งนี้เป็นการจัดซื้อที่ยกเว้นเงื่อนไขทั่วไปประกอบการจัดซื้อพัสดุ ข้อ 6 ดังนั้น ผู้เสนอราคาต้องเสนอรายละเอียดทางเทคนิค โดยต้องยื่นเอกสาร แคตตาล็อกและ/แบบรูปแสดงรายละเอียดคุณลักษณะเฉพาะ ไม่สามารถยื่นใบขึ้น ทะเบียนและรับรองผลิตภัณฑ์ PEA Product Acceptance
    ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจ 1-มป-010-2569 Specification No. RTRN-035/2568
    C3 Schedule of detailed requirement
    Item

• 57 -
  PEA
  Material Quantity
  No.
  Description

13. สถานที่ส่งมอบและเงื่อนไขการแจ้งสถานที่
    คู่สัญญาต้องส่งมอบพัสดุ ณ สถานที่ของคู่สัญญา ซึ่งต้องตั้งอยู่ภายในรัศมี
    180 กิโลเมตร นับจากสํานักงานกองจัดการโลจิสติกส์ภาคกลาง (รังสิต) หรือใน พื้นที่
    กรุงเทพฯ และปริมณฑล โดยคู่สัญญาต้องแจ้งที่ตั้งสถานที่ส่งมอบพัสดุ ของคู่สัญญาเป็นหนังสือให้การไฟฟ้าส่วนภูมิภาคทราบ ภายใน 7 วัน นับถัดจาก
    วันที่ลงนามในสัญญา

• ประกวดราคานี้กําหนดระยะทางโดยพิจารณาจากตําแหน่งที่ตั้งของผู้ประกอบการ
  ที่เคยเข้าร่วมเสนอราคากับการไฟฟ้าส่วนภูมิภาค

14. ความรับผิดชอบและการจัดเก็บพัสดุ (กรณีตรวจรับ ณ สถานที่ของคู่สัญญา)
    เมื่อการไฟฟ้าส่วนภูมิภาค ได้ทําการตรวจรับพัสดุไว้ถูกต้องเรียบร้อยแล้ว ให้ถือว่าการไฟฟ้าส่วนภูมิภาค ได้รับพัสดุไว้ถูกต้องครบถ้วนตามสัญญา แต่ คู่สัญญายังคงมีหน้าที่และความรับผิดชอบดังนี้
    14.1 คู่สัญญาต้องดําเนินการ จัดเก็บรักษาพัสดุไว้ ณ สถานที่ของคู่สัญญา อย่างเหมาะสม ปลอดภัย สะดวกต่อการตรวจนับ จนกว่าการไฟฟ้า ส่วนภูมิภาคจะนํายานพาหนะมาขนย้ายพัสดุดังกล่าว
    14.2 ในระหว่างการจัดเก็บพัสดุ คู่สัญญาต้องรับผิดชอบต่อ ความสูญหาย หรือเสียหายใด ๆ อันอาจเกิดกับพัสดุที่จัดเก็บรักษาไว้ รวมถึงกรณี เกิดเหตุสุดวิสัยทุกกรณี
    14.3 คู่สัญญาต้องรับผิดชอบค่าใช้จ่ายในการดําเนินการจัดเก็บและดําเนินการ
    นําพัสดุขึ้นบนยานพาหนะ ที่การไฟฟ้าส่วนภูมิภาคจัดหามาเพื่อทําการ ขนส่งพัสดุไปยังคลังพัสดุ หรือจุดใช้งานของการไฟฟ้าส่วนภูมิภาค 14.4 การไฟฟ้าส่วนภูมิภาคมีสิทธิ์ในการส่งเจ้าหน้าที่เข้าตรวจสอบตรวจ นับพัสดุที่ จัดเก็บรักษาไว้ ณ สถานที่ของคู่สัญญา ได้ตลอดเวลา จนกว่าการไฟฟ้าส่วนภูมิภาคจะดําเนินการขนย้ายพัสดุแล้วเสร็จ
    ประกวดราคาอิเล็กทรอนิกส์ เลขที่ กจ 1-มป-010-2569 Specification No. RTRN-035/2568
    C3 Schedule of detailed requirement

• 58 -
  Item
  PEA
  Material Quantity
  No.
  Description

15. กําหนดส่งมอบแต่ละรายการ ให้นับถัดจากวันลงนามในสัญญาซื้อขาย และภายในงวด สามารถทยอยการจัดส่งได้ โดยในการตรวจรับพัสดุ คณะกรรมการตรวจรับพัสดุจะ ทําการตรวจรับฯ เมื่อคู่สัญญาส่งพัสดุครบจํานวนตามที่กําหนดในงวดนั้นๆ ดังนี้ รายการที่ 1 แบ่งเป็น 2 งวด ดังนี้
    งวดที่ 1
    1 จํานวน 10 เครื่อง ภายใน 45 วัน งวดที่ 2 จํานวน 13 เครื่อง ภายใน 15 วัน
    รายการที่ 2 งวดเดียว ภายใน 45 วัน
16. กําหนดการขนย้ายและการตรวจสอบพัสดุ ณ ปลายทาง
    16.1 การไฟฟ้าส่วนภูมิภาคจะดําเนินการขนย้ายพัสดุออกจาก สถานที่ของ คู่สัญญา ภายใน 15 วัน นับจากวันรับพัสดุเข้าบัญชีในแต่ละงวด 16.2 เมื่อพัสดุถึงปลายทาง (คลังพัสดุ หรือจุดใช้งานพัสดุ) ผู้รับพัสดุของการไฟฟ้า ส่วนภูมิภาคจะทําการตรวจสอบความถูกต้องอีกครั้ง และแจ้งหนังสือผลการ ตรวจสอบให้คู่สัญญาทราบ ภายใน 7 วัน หากตรวจสอบแล้วพบว่าพัสดุ ชํารุดบกพร่อง เสียหาย อันพิสูจน์ได้ว่าเกิดจากการนําพัสดุขึ้นบน ยานพาหนะ คู่สัญญาต้องรับกลับไปดําเนินการแก้ไขให้ถูกต้องเรียบร้อย ภายใน 30 วัน นับถัดจากวันที่ได้รับหนังสือแจ้งผลการตรวจสอบจาก การไฟฟ้าส่วนภูมิภาค โดยคู่สัญญาเป็นผู้รับผิดชอบค่าใช้จ่ายทั้งหมด

• 59 -
  PRELIMINARY
  For permanently sealed and
  completely oil filled system (without gas cushion) type
  1
  A
  B
  4 (5
  3
  2
  6
  17
  (20
  (19
  18
  HE
  16
  15
  8
  Not less than
  200,mm
  9
  10
  11
  NO.

Lifting lugs
2. Lifting eyes
O+
3.
HV Bushing
4.
Thermometer pocket
5.
Pressure relief valve
(12
(13
DESCRIPTION
6. Off-load tap changer
7.
LV Bushing
8.
Support lugs
(Only for transformer of 50-250 kVA)
9.
Oil level gauge
See detail B
10. Oil
Oil filling plug
TANK
See detail A
11. Surge arrester (Polymer housing type)
12. Bracket for surge arrester
13. Earthing terminal for surge arrester
14. Corrugated radiator
15. Earthing terminal
Note:

1. Surge arrester, line lead and ground lead, supplied by PEA

Sludge drain plug
17.
Oil drain valve
2. Earthing terminal for surge arrester shall be eye-bolt type or socket type. 18. 3. Position of earthing terminal for surge arrester shall be suitable for flexible copper insulated ground lead size 16 sq.mm, 430 mm long.
Bird guard cop
19.
Coble lug
20.
Transporter roller
EME
(Only for transformer of 315-500 KVA)
14
PEA
มิติเป็น..
กองวิศวกรรมไฟฟ้าและเครื่องกล ฝ่ายวิศวกรรม การไฟฟ้าส่วนภูมิภาค
มิลลิเมตร
й 17 SEP 2025
THREE-PHASE TRANSFORMERS
Not to scale
แบบเลขที SB4-015/68001……
แผ่นที่ 1 ของจํานวน 5

• 60 -
  For conservator system type
  PRELIMINARY
  6
  3
  4
  5
  7

H
00
8
9
19
(20
10
11
(21)
||FF||
(12)
13
Not less than 200 mm
(14)
(15)
16
(22
NO.
10

1. | Lifting luga
   DESCRIPTION
   Note :

Lifting eyes
3.
HV Bushing
4.
Thermometer pocket
5.
Dial type thermometer
(Only for 1,000-2,000 KVA transformers)
6.
Pressure relief vent
(Only for 1,000-2.000 KVA transformers)
7.
Off-load top changer
8.
LV Bushing
9.
10.
See detail 8
11.
TANK
See detail A

1. Surge arrester, line lead and ground lead, supplied by PEA
2. Earthing terminal for surge arrester shall be eye-bolt type or socket type.
3. Position of earthing terminal for surge arrester shall be suitable for flexible copper insulated ground lead size 16 sq.mm, 430 mm long.
4. Only for 1,000-2,000 KVA transformers shall be furnished and equipped with:
   (a) Dial type thermometer with adjustable contact(s)
   Buchholz relay
   (Only for 1,000-2,000 KVA transformers) Conservator
   Oil level gauge
   Surge arrester (Polymer housing type)
5. Bracket for surge arrester
6. Earthing terminal for surge arrester
7. Rodiator
8. Earthing terminal
9. Sludge drain plug
10. Oil drain valve
11. Bird guard cap
12. Cable lug
13. Dehydrating breather
14. Transport rollers
    (b) Double float Buchholz relay having two (2) contacts (for alarm and tripping) (c) Pressure relief vent (explosion vent) with metal bursting plate
    EME
    กองวิศวกรรมไฟฟ้าและเครื่องกล ฝ่ายวิศวกรรม การไฟฟ้าส่วนภูมิภาค
    PEA
    มิติเป็น มิลลิเมตร
    #17 SEP 2025
    วันที่
    ……
    Not to scale
    แบบเลขที่
    SB4-015/68001
    THREE-PHASE TRANSFORMERS
    แผ่นที่…… 2
    ของจํานวน 6