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GB/Z 1094.20-2026Power transformers - Part 20: Energy efficiency (English PDF)

电力变压器第20部分：能效

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Issued by

SAMR; SAC

Level / Type

National · Recommended

Issue date

July 2, 2026

Implementation date

July 2, 2026

Scope

GB/Z 1094.20-2026 is the English-translated version of 电力变压器第20部分：能效.

GB/Z 1094.20-2026 is the Chinese standard "Power transformers - Part 20: Energy efficiency". Its scope clause reads: This document specifies the energy efficiency indicators for power transformers, and provides the energy efficiency calculation method and energy efficiency limit values.

This document applies to power transformers within the scope of GB/T 1094.1 and GB/T 1094.11.

The energy efficiency levels given in Chapter 6 do not apply to the following transformers. --Transformers for high-current rectifiers as described in GB/T 18494 (all parts) and GB/T 3859 (all parts); --Electric furnace transformer; --Offshore transformer; Note 1.Transformers installed on fixed or floating offshore platforms, offshore wind turbines, or ships. --Transformers for emergency or temporary mobile devices; Note 2.The transformer is designed for use only for a specific, limited time when normal power supply is interrupted due to unforeseen events (such as faults or power plant renovations), and is not intended for permanent use.

Upgrade existing substations. --Traction transformers used in traction substations of electrified railways; --Grounding transformer (as defined in 3.1.10 of GB/T 1094.6-2011); --Phase-shifting transformer; --Submarine transformer; --Starting up, testing, and welding transformers; --Starting transformer, specifically designed for starting three-phase induction motors to eliminate sudden drops in power supply voltage; --Transformers specifically designed for explosion-proof and underground mining applications; --Gas-filled transformer; --Transformers that cannot meet energy efficiency requirements due to unavoidable size and weight limitations.

Note 4.Due to unavoidable weight and size limitations in locomotive and rolling stock applications, this definition includes all locomotive and rolling stock traction transformers, regardless of frequency (e.g., 16.7 Hz).

25 Hz, 50 Hz and 60 Hz). In this document, “transformer” includes both independent winding transformers and autotransformers. Its clauses include terms and definitions.

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Document preview — GB/Z 1094.20-2026

National Standard of the People's Republic of China

ICS: 29.180
Classification: K 41

Issued by: State Administration for Market Regulation; Standardization Administration of the PRC

1.Scope1
2 Normative references1
3.Terms and Definitions1
4.Efficiency and Efficiency Indicator Calculation2
5 Energy Efficiency Standards4
6.Energy efficiency level4
7 Deviations24
Appendix A (Normative) Loss Evaluation25
Figure A.1 Load Conditions27
Table 2 Energy Efficiency of 6 kV and 10 kV Three-Phase Double-Winding Off-Field Voltage Regulating Power Transformers5
Table 3 Energy efficiency of 6 kV and 10 kV three-phase double-winding on-load tap-changing distribution transformers5
Table 5 Energy efficiency of 20 kV three-phase double-winding off-grid voltage regulating distribution transformers6
Table 6 Energy Efficiency of 20 kV Single-Phase Double-Winding Off-Field Voltage Regulating Distribution Transformers7
Table 7 Energy Efficiency of 35 kV Three-Phase Double-Winding Off-Grid Voltage Regulating Distribution Transformers8
Table 8.Energy Efficiency of 35 kV Three-Phase Double-Winding Off-Field Voltage Regulating Power Transformers8
Table 9.Energy Efficiency of 35 kV Three-Phase Double-Winding On-Load Tap-Changing Power Transformers9
Table 10 Energy Efficiency of 66 kV Three-Phase Double-Winding Off-Field Voltage Regulating Power Transformers9
Table 11 Energy Efficiency of 66 kV Three-Phase Double-Winding On-Load Tap-Changing Power Transformers10
Table 12 Energy Efficiency of 110 kV Three-Phase Double-Winding Off-Field Voltage Regulating Power Transformers11
Table 13 Energy Efficiency of 110 kV Three-Phase Three-Winding Off-Field Voltage Regulating Power Transformers11
Table 14 Energy Efficiency of 110 kV Three-Phase Double-Winding On-Load Tap-Changing Power Transformers12
Table 15 Energy Efficiency of 110 kV Three-Phase Three-Winding On-Load Tap-Changing Power Transformers12
Table 17 Energy Efficiency of 220 kV Three-Phase Double-Winding Off-Field Voltage Regulating Power Transformers13
Table 18 Energy Efficiency of 220 kV Three-Phase Three-Winding Off-Field Voltage Regulating Power Transformers13
Table 20 Energy Efficiency of 220 kV Three-Phase Three-Winding Off-Field Voltage Regulating Autotransformer14
Table 21 Energy Efficiency of 220 kV Three-Phase Double-Winding On-Load Tap-Changing Power Transformers15
Table 22 Energy Efficiency of 220 kV Three-Phase Three-Winding On-Load Tap-Changing Power Transformers15
Table 23 Energy Efficiency of 220 kV Three-Phase Three-Winding On-Load Tap-Changing Autotransformer15
Table 24 Energy Efficiency of 330 kV Three-Phase Double-Winding Off-Field Voltage Regulating Power Transformers16
Table 25 Energy Efficiency of 330 kV Three-Phase Three-Winding Off-Field Voltage Regulating Power Transformers16
Table 31 Energy Efficiency of 500 kV Single-Phase Double-Winding Power Transformers18
Table 32 Energy Efficiency of 500 kV Three-Phase Double-Winding Power Transformers18
Table 35 Energy Efficiency of 750 kV Single-Phase Double-Winding Power Transformers19
Table 36 Energy Efficiency of 750 kV Three-Phase Double-Winding Power Transformers19
Table 37 Energy Efficiency of 750 kV Single-Phase Three-Winding Autotransformer19
Table 38 Energy Efficiency of 1000 kV Single-Phase Double-Winding Off-Field Voltage Regulating Power Transformers20
Table 41 Energy Efficiency of 6 kV and 10 kV Class Non-excitation Voltage Regulating Dry-type Distribution Transformers20
Table 42 Energy Efficiency of 6 kV and 10 kV Class Unloaded Voltage Regulating Dry-Type Power Transformers21
Table 43 Energy Efficiency of 6 kV and 10 kV On-Load Tap-Changing Dry-Type Distribution Transformers22
Table 44 Energy Efficiency of 20 kV Class Unloaded Voltage Regulating Dry-Type Distribution Transformers22
Table 45 Energy Efficiency of 35 kV Class Unloaded Voltage Regulating Dry-Type Distribution Transformers23
Table 46 Energy Efficiency of 35 kV Class Unloaded Voltage Regulating Dry-Type Power Transformers23
Table 47 Energy Efficiency of 35 kV On-Load Tap-Changing Dry-Type Power Transformers24

1 Scope

This document specifies the energy efficiency indicators for power transformers, and provides the energy efficiency calculation method and energy efficiency limit values.

This document applies to power transformers within the scope of GB/T 1094.1 and GB/T 1094.11.

The energy efficiency levels given in Chapter 6 do not apply to the following transformers.

--Transformers for high-current rectifiers as described in GB/T 18494 (all parts) and GB/T 3859 (all parts);

--Electric furnace transformer;

--Offshore transformer;

Note 1.Transformers installed on fixed or floating offshore platforms, offshore wind turbines, or ships.

--Transformers for emergency or temporary mobile devices;

Note 2.The transformer is designed for use only for a specific, limited time when normal power supply is interrupted due to unforeseen events (such as faults or power plant renovations), and is not intended for permanent use.

Upgrade existing substations.

--Traction transformers used in traction substations of electrified railways;

--Grounding transformer (as defined in 3.1.10 of GB/T 1094.6-2011);

--Phase-shifting transformer;

--Submarine transformer;

--Starting up, testing, and welding transformers;

--Starting transformer, specifically designed for starting three-phase induction motors to eliminate sudden drops in power supply voltage;

--Transformers specifically designed for explosion-proof and underground mining applications;

--Gas-filled transformer;

--Transformers that cannot meet energy efficiency requirements due to unavoidable size and weight limitations.

25 Hz, 50 Hz and 60 Hz).

In this document, “transformer” includes both independent winding transformers and autotransformers.

2 Normative references

The contents of the following documents, through normative references within the text, constitute essential provisions of this document. Dated citations are listed below.

For references to documents, only the version corresponding to that date applies to this document; for undated references, the latest version (including all amendments) applies.

This document.

GB/T 1094.1 Power Transformers - Part 1.General (GB/T 1094.1-2013, IEC 60076-1.2011, MOD)

GB/T 1094.2 Power Transformers - Part 2.Temperature Rise of Liquid-Immersed Transformers (GB/T 1094.2-2013, IEC 60076-2)

2011, MOD)

GB/T 1094.11 Power Transformers - Part 11.Dry-type Transformers (GB/T 1094.11-2022, IEC 60076-11.)

2018, MOD)

3 Terms and Definitions

The terms and definitions defined in GB/T 1094.1 and GB/T 1094.11, as well as the following terms and definitions, apply to this document.

......
This preview omits tables, figures, formulas and parts of the technical clauses. The complete document — 37 pages — is available in the English PDF.

Similar standards

GB/T 25438-2026|GB/T 32825-2024|GB/T 10228-2023|GB/T 1094.101-2023|GB/T 18494.3-2023|GB/T 6451-2023

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