GB/T 25438-2026 Technical parameters and requirements for three-phase oil-immersed tridimensional wound core power transformers English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
CCS
National Standard of the People's Republic of China
GB/T 25438-2026
Technical parameters and requirements for three-phase oil-immersed tridimensional wound core power transformers
三相油浸式立体卷铁芯电力变压器技术参数和要求
Issue date: 2026-06-27 Implementation date: 2027-05-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 6 kV and 10 kV voltage classes
5 20 kV voltage class
6 35 kV voltage class
Annex A (normative) Testing of transformers with dual high-voltage of 20(10) kV
Figure 1 — Positions of bottom supports for 6 kV and 10 kV transformers
Figure 2 — Bushing arrangement for 6 kV and 10 kV transformers
Figure 3 — Positions of bottom supports for 20 kV transformers
Figure 4 — Bushing arrangement for 20 kV transformers
Figure 5 — Positions of bottom supports for 35 kV transformers
Figure 6 — Bushing arrangement for 35 kV transformers with connection symbols Dyn11 and Yyn0
Figure 7 — Bushing arrangement for 35 kV transformers with connection symbol Yd11
Figure 8 — Bushing arrangement for 35 kV transformers with connection symbol YNd11
Table 1 — 6 kV and 10 kV, 30 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 2 — 6 kV and 10 kV, 630 kVA to 6300 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core power transformers
Table 3 — 6 kV and 10 kV, 200 kVA to 4000 kVA, three-phase oil-immersed on-load tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 4 — 6 kV and 10 kV, 30 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 5 — 6 kV and 10 kV, 200 kVA to 4000 kVA, three-phase oil-immersed on-load tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 6 — 6 kV and 10 kV, 30 kVA to 4000 kVA, three-phase oil-immersed grain-oriented silicon steel three-dimensional wound core transformers — Sound power level limits
Table 7 — 6 kV and 10 kV, 30 kVA to 4000 kVA, three-phase oil-immersed amorphous alloy three-dimensional wound core transformers — Sound power level limits
Table 8 — 20 kV, 30 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 9 — 20 kV, 30 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 10 — 20 kV, 30 kVA to 4000 kVA, three-phase oil-immersed grain-oriented silicon steel three-dimensional wound core transformers — Sound power level limits
Table 11 — 20 kV, 30 kVA to 4000 kVA, three-phase oil-immersed amorphous alloy three-dimensional wound core transformers — Sound power level limits
Table 12 — 35 kV, 50 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 13 — 35 kV, 630 kVA to 31500 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core power transformers
Table 14 — 35 kV, 630 kVA to 4000 kVA, three-phase oil-immersed on-load tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 15 — 35 kV, 2000 kVA to 31500 kVA, three-phase oil-immersed on-load tap-changing grain-oriented silicon steel three-dimensional wound core power transformers
Table 16 — 35 kV, 50 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 17 — 35 kV, 630 kVA to 4000 kVA, three-phase oil-immersed on-load tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 18 — 35 kV, 50 kVA to 31500 kVA, three-phase oil-immersed grain-oriented silicon steel three-dimensional wound core transformers — Sound power level limits
Table 19 — 35 kV, 30 kVA to 4000 kVA, three-phase oil-immersed amorphous alloy three-dimensional wound core transformers — Sound power level limits
Table 20 — Vacuum and positive pressure values for 35 kV transformer tanks
Three-phase oil-immersed three-dimensional wound core power transformers — Technical parameters and requirements
1 Scope
This document specifies the performance parameters, technical requirements, inspection rules, marking, lifting, packaging, transportation and storage for three-phase oil-immersed three-dimensional wound core power transformers, and describes the corresponding test methods.
This document is applicable to the manufacture of three-phase oil-immersed three-dimensional wound core power transformers with a rated frequency of 50 Hz, rated capacity of 30 kVA and above, core materials of grain-oriented silicon steel and amorphous alloy, voltage classes of 6 kV, 10 kV, 20 kV and 35 kV, and with off-circuit tap-changing and on-load tap-changing.
Note: Where no confusion arises, "three-phase oil-immersed three-dimensional wound core power transformer" in this document is referred to as "transformer".
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 1094.1, Power transformers — Part 1: General
GB/T 1094.2, Power transformers — Part 2: Temperature rise for liquid-immersed transformers
GB/T 1094.3, Power transformers — Part 3: Insulation levels, dielectric tests and external clearances in air
GB/T 1094.5, Power transformers — Part 5: Ability to withstand short circuit
GB/T 1094.7, Power transformers — Part 7: Loading guide for oil-immersed power transformers
GB/T 1094.10, Power transformers — Part 10: Determination of sound levels
GB/T 2900.95, Electrotechnical terminology — Transformers, voltage regulators and reactors
GB/T 25446, Technical parameters and requirements for oil-immersed amorphous alloy core distribution transformers
JB/T 501, Guide for testing power transformers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 1094.1, GB/T 2900.95 and GB/T 25446, as well as the following, apply.
3.1
three-dimensional wound core
A core composed of three single-frame wound cores with identical geometric dimensions, assembled into a triangular three-dimensional arrangement.
3.2
three-dimensional wound core power transformer
A power transformer with a three-dimensional wound core as the magnetic circuit.
4 6 kV and 10 kV voltage classes
4.1 Performance parameters
The rated capacity, voltage combinations and tapping ranges, connection symbols, no-load losses, load losses, no-load current and short-circuit impedance shall comply with Tables 1 to 5.
4.2 Technical requirements
4.2.1 General requirements
In addition to complying with GB/T 1094.1, GB/T 1094.2, GB/T 1094.3, GB/T 1094.5 and GB/T 1094.7, transformers shall also comply with 4.2.2 to 4.2.6.
4.2.2 Sound levels
The sound levels of transformers shall comply with Tables 6 and 7. The sound level measurement method shall be in accordance with GB/T 1094.10.
4.2.3 Safety protection devices
Transformers of 800 kVA and above should preferably be equipped with gas relays. By agreement between the user and the manufacturer, transformers below 800 kVA may be equipped with gas relays. Corrugated tank transformers, transformers with elastic finned radiators or sealed transformers with gas filled inside the tank generally are not equipped with gas relays.
The contact capacity of the gas relay shall not be less than 66 VA at AC 220 V or 110 V, and not less than 15 W for DC inductive loads. When the amount of gas accumulated in the gas relay reaches the specified range or the oil flow rate reaches the set value, the corresponding contacts shall be closed respectively. The installation position and structure of the gas relay shall allow observation of the accumulated gas volume and the oil flow rate scale, and shall facilitate gas sampling.
Transformers shall be equipped with pressure protection devices. When the pressure inside the transformer tank reaches the safety limit, the pressure protection device shall reliably release the pressure.
For transformers equipped with pressure protection devices, it shall be ensured that the pressure protection device does not operate under maximum ambient temperature and allowable overload conditions, and can operate normally under minimum ambient temperature and no-load conditions.
4.2.4 Oil preservation devices
4.2.4.1 Transformers shall be equipped with oil conservators (except for corrugated tank transformers, transformers with elastic finned radiators or sealed transformers with gas filled inside the tank), and the structure shall facilitate internal cleaning. The oil conservator shall have an oil level indication function, and its volume shall ensure that the oil level does not exceed the upper limit under maximum ambient temperature and allowable overload conditions, and that the oil level indication can be observed under minimum ambient temperature and when the transformer is not energised.
4.2.4.2 The oil conservator shall be provided with oil filling and oil draining devices.
4.2.4.3 The oil conservator should preferably be equipped with a breather with oil seal.
4.2.5 Oil temperature measuring devices
4.2.5.1 Transformers shall be provided with a socket for a thermometer. The socket shall be installed at the top of the tank, away from areas with strong leakage magnetic fields, and shall extend into the oil by 120 mm ± 10 mm.
4.2.5.2 Transformers of 1000 kVA and above shall be equipped with outdoor temperature measuring devices, with contact capacity not less than 50 VA at AC 220 V and not less than 15 W for DC inductive loads. The installation position of the temperature measuring device shall be convenient for observation.
By agreement between the user and the manufacturer, transformers below 1000 kVA may be equipped with outdoor temperature measuring devices.
4.2.6 Transformer tank and accessories
4.2.6.1 Transformers are generally not supplied with trolleys. If supports are welded to the bottom of the tank, the welding positions shall comply with Figure 1. Trolleys may be supplied according to user requirements.
4.2.6.2 An oil drain valve may be installed on the lower wall of the transformer tank.
4.2.6.3 At the connection points of the bushing terminals, the temperature rise relative to the ambient air shall not exceed 55 K, and the temperature rise relative to the oil shall not exceed 15 K.
4.2.6.4 The installation positions and spacing of bushings shall facilitate connection, and the air clearances of live parts shall comply with GB/T 1094.3.
4.2.6.5 Sealed transformers with gas filled inside the tank shall meet insulation requirements under minimum oil level conditions.
Standard
GB/T 25438-2026 Technical parameters and requirements for three-phase oil-immersed tridimensional wound core power transformers (English)
Standard No.
GB/T 25438-2026
Status
to be valid
Language
English
File Format
PDF
Word Count
21500 words
Translation Price(USD)
645.0
Implemented on
2027-2-1
Delivery
via email in 1~8 business day
Detail of GB/T 25438-2026
Standard No.
GB/T 25438-2026
English Name
Technical parameters and requirements for three-phase oil-immersed tridimensional wound core power transformers
GB/T 25438-2026 Technical parameters and requirements for three-phase oil-immersed tridimensional wound core power transformers English, Anglais, Englisch, Inglés, えいご
This is a draft translation for reference among interesting stakeholders. The finalized translation (passing through draft translation, self-check, revision and verification) will be delivered upon being ordered.
ICS
CCS
National Standard of the People's Republic of China
GB/T 25438-2026
Technical parameters and requirements for three-phase oil-immersed tridimensional wound core power transformers
三相油浸式立体卷铁芯电力变压器技术参数和要求
Issue date: 2026-06-27 Implementation date: 2027-05-01
Issued by the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China
the Standardization Administration of the People's Republic of China
Contents
Foreword
1 Scope
2 Normative references
3 Terms and definitions
4 6 kV and 10 kV voltage classes
5 20 kV voltage class
6 35 kV voltage class
Annex A (normative) Testing of transformers with dual high-voltage of 20(10) kV
Figure 1 — Positions of bottom supports for 6 kV and 10 kV transformers
Figure 2 — Bushing arrangement for 6 kV and 10 kV transformers
Figure 3 — Positions of bottom supports for 20 kV transformers
Figure 4 — Bushing arrangement for 20 kV transformers
Figure 5 — Positions of bottom supports for 35 kV transformers
Figure 6 — Bushing arrangement for 35 kV transformers with connection symbols Dyn11 and Yyn0
Figure 7 — Bushing arrangement for 35 kV transformers with connection symbol Yd11
Figure 8 — Bushing arrangement for 35 kV transformers with connection symbol YNd11
Table 1 — 6 kV and 10 kV, 30 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 2 — 6 kV and 10 kV, 630 kVA to 6300 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core power transformers
Table 3 — 6 kV and 10 kV, 200 kVA to 4000 kVA, three-phase oil-immersed on-load tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 4 — 6 kV and 10 kV, 30 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 5 — 6 kV and 10 kV, 200 kVA to 4000 kVA, three-phase oil-immersed on-load tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 6 — 6 kV and 10 kV, 30 kVA to 4000 kVA, three-phase oil-immersed grain-oriented silicon steel three-dimensional wound core transformers — Sound power level limits
Table 7 — 6 kV and 10 kV, 30 kVA to 4000 kVA, three-phase oil-immersed amorphous alloy three-dimensional wound core transformers — Sound power level limits
Table 8 — 20 kV, 30 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 9 — 20 kV, 30 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 10 — 20 kV, 30 kVA to 4000 kVA, three-phase oil-immersed grain-oriented silicon steel three-dimensional wound core transformers — Sound power level limits
Table 11 — 20 kV, 30 kVA to 4000 kVA, three-phase oil-immersed amorphous alloy three-dimensional wound core transformers — Sound power level limits
Table 12 — 35 kV, 50 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 13 — 35 kV, 630 kVA to 31500 kVA, three-phase oil-immersed off-circuit tap-changing grain-oriented silicon steel three-dimensional wound core power transformers
Table 14 — 35 kV, 630 kVA to 4000 kVA, three-phase oil-immersed on-load tap-changing grain-oriented silicon steel three-dimensional wound core distribution transformers
Table 15 — 35 kV, 2000 kVA to 31500 kVA, three-phase oil-immersed on-load tap-changing grain-oriented silicon steel three-dimensional wound core power transformers
Table 16 — 35 kV, 50 kVA to 4000 kVA, three-phase oil-immersed off-circuit tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 17 — 35 kV, 630 kVA to 4000 kVA, three-phase oil-immersed on-load tap-changing amorphous alloy three-dimensional wound core distribution transformers
Table 18 — 35 kV, 50 kVA to 31500 kVA, three-phase oil-immersed grain-oriented silicon steel three-dimensional wound core transformers — Sound power level limits
Table 19 — 35 kV, 30 kVA to 4000 kVA, three-phase oil-immersed amorphous alloy three-dimensional wound core transformers — Sound power level limits
Table 20 — Vacuum and positive pressure values for 35 kV transformer tanks
Three-phase oil-immersed three-dimensional wound core power transformers — Technical parameters and requirements
1 Scope
This document specifies the performance parameters, technical requirements, inspection rules, marking, lifting, packaging, transportation and storage for three-phase oil-immersed three-dimensional wound core power transformers, and describes the corresponding test methods.
This document is applicable to the manufacture of three-phase oil-immersed three-dimensional wound core power transformers with a rated frequency of 50 Hz, rated capacity of 30 kVA and above, core materials of grain-oriented silicon steel and amorphous alloy, voltage classes of 6 kV, 10 kV, 20 kV and 35 kV, and with off-circuit tap-changing and on-load tap-changing.
Note: Where no confusion arises, "three-phase oil-immersed three-dimensional wound core power transformer" in this document is referred to as "transformer".
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition (including any amendments) applies.
GB/T 1094.1, Power transformers — Part 1: General
GB/T 1094.2, Power transformers — Part 2: Temperature rise for liquid-immersed transformers
GB/T 1094.3, Power transformers — Part 3: Insulation levels, dielectric tests and external clearances in air
GB/T 1094.5, Power transformers — Part 5: Ability to withstand short circuit
GB/T 1094.7, Power transformers — Part 7: Loading guide for oil-immersed power transformers
GB/T 1094.10, Power transformers — Part 10: Determination of sound levels
GB/T 2900.95, Electrotechnical terminology — Transformers, voltage regulators and reactors
GB/T 25446, Technical parameters and requirements for oil-immersed amorphous alloy core distribution transformers
JB/T 501, Guide for testing power transformers
3 Terms and definitions
For the purposes of this document, the terms and definitions given in GB/T 1094.1, GB/T 2900.95 and GB/T 25446, as well as the following, apply.
3.1
three-dimensional wound core
A core composed of three single-frame wound cores with identical geometric dimensions, assembled into a triangular three-dimensional arrangement.
3.2
three-dimensional wound core power transformer
A power transformer with a three-dimensional wound core as the magnetic circuit.
4 6 kV and 10 kV voltage classes
4.1 Performance parameters
The rated capacity, voltage combinations and tapping ranges, connection symbols, no-load losses, load losses, no-load current and short-circuit impedance shall comply with Tables 1 to 5.
4.2 Technical requirements
4.2.1 General requirements
In addition to complying with GB/T 1094.1, GB/T 1094.2, GB/T 1094.3, GB/T 1094.5 and GB/T 1094.7, transformers shall also comply with 4.2.2 to 4.2.6.
4.2.2 Sound levels
The sound levels of transformers shall comply with Tables 6 and 7. The sound level measurement method shall be in accordance with GB/T 1094.10.
4.2.3 Safety protection devices
Transformers of 800 kVA and above should preferably be equipped with gas relays. By agreement between the user and the manufacturer, transformers below 800 kVA may be equipped with gas relays. Corrugated tank transformers, transformers with elastic finned radiators or sealed transformers with gas filled inside the tank generally are not equipped with gas relays.
The contact capacity of the gas relay shall not be less than 66 VA at AC 220 V or 110 V, and not less than 15 W for DC inductive loads. When the amount of gas accumulated in the gas relay reaches the specified range or the oil flow rate reaches the set value, the corresponding contacts shall be closed respectively. The installation position and structure of the gas relay shall allow observation of the accumulated gas volume and the oil flow rate scale, and shall facilitate gas sampling.
Transformers shall be equipped with pressure protection devices. When the pressure inside the transformer tank reaches the safety limit, the pressure protection device shall reliably release the pressure.
For transformers equipped with pressure protection devices, it shall be ensured that the pressure protection device does not operate under maximum ambient temperature and allowable overload conditions, and can operate normally under minimum ambient temperature and no-load conditions.
4.2.4 Oil preservation devices
4.2.4.1 Transformers shall be equipped with oil conservators (except for corrugated tank transformers, transformers with elastic finned radiators or sealed transformers with gas filled inside the tank), and the structure shall facilitate internal cleaning. The oil conservator shall have an oil level indication function, and its volume shall ensure that the oil level does not exceed the upper limit under maximum ambient temperature and allowable overload conditions, and that the oil level indication can be observed under minimum ambient temperature and when the transformer is not energised.
4.2.4.2 The oil conservator shall be provided with oil filling and oil draining devices.
4.2.4.3 The oil conservator should preferably be equipped with a breather with oil seal.
4.2.5 Oil temperature measuring devices
4.2.5.1 Transformers shall be provided with a socket for a thermometer. The socket shall be installed at the top of the tank, away from areas with strong leakage magnetic fields, and shall extend into the oil by 120 mm ± 10 mm.
4.2.5.2 Transformers of 1000 kVA and above shall be equipped with outdoor temperature measuring devices, with contact capacity not less than 50 VA at AC 220 V and not less than 15 W for DC inductive loads. The installation position of the temperature measuring device shall be convenient for observation.
By agreement between the user and the manufacturer, transformers below 1000 kVA may be equipped with outdoor temperature measuring devices.
4.2.6 Transformer tank and accessories
4.2.6.1 Transformers are generally not supplied with trolleys. If supports are welded to the bottom of the tank, the welding positions shall comply with Figure 1. Trolleys may be supplied according to user requirements.
4.2.6.2 An oil drain valve may be installed on the lower wall of the transformer tank.
4.2.6.3 At the connection points of the bushing terminals, the temperature rise relative to the ambient air shall not exceed 55 K, and the temperature rise relative to the oil shall not exceed 15 K.
4.2.6.4 The installation positions and spacing of bushings shall facilitate connection, and the air clearances of live parts shall comply with GB/T 1094.3.
4.2.6.5 Sealed transformers with gas filled inside the tank shall meet insulation requirements under minimum oil level conditions.
