For Industry

Distribution transformers

Artistic photo of power distribution infrastructure

Overview

Distribution transformers are used in electricity distribution systems to step down power to the voltage required by the end product. Distribution transformers are categorised based on factors such as location, insulation type, number of phases and voltage classes.

At a Glance

Determination	Minimum Energy Performance Standards	Energy Rating Label
Greenhouse and Energy Minimum Standards (Power Transformers) Determination 2012	Yes	No

Legislation

In Australia, this product is regulated under the Greenhouse and Energy Minimum Standards Act 2012.

In New Zealand, the relevant legislation is the Energy Efficiency (Energy Using Products) Regulations 2002. Visit the Energy Efficiency and Conservation Authority website for more information.

What products are covered?

Products covered by this Determination include power transformers with power ratings from 10 kVA to 2500 kVA and a system highest voltage up to 24 kV. This includes:

single phase or single wire earth return oil-immersed transformers
three phase, oil immersed transformers
single phase or single wire earth return, dry-type distribution transformers with a system highest voltage of 12 kV or 24 kV
three phase dry-type distribution transformers with a system highest voltage of 12 kV or 24 kV.

For the Determination, power transformers are static pieces of apparatus with two or more windings which, by electromagnetic induction, transform a system of alternating voltage and current into another system of voltage and current usually of different values and at the same frequency for the purpose of transmitting electrical power.

Refer to section 5 of the Determination for further information.

What products are not covered?

The following products are not covered by this Determination.

Transformers other than those designed for 11 or 22 kV networks.
Instrument transformers.
Auto transformers, that is transformers in which at least two windings have a common part.
Traction transformers mounted on rolling stock.
Starting transformers.
Testing transformers.
Welding transformers.
Three phase transformers with three or more windings per phase.
Arc-furnace transformers.
Earthing transformers.
Rectifier or converter transformers.
Uninterruptible power supply transformers.
Transformers with an impedance less than 3 per cent or more than 8 per cent.
Voltage regulating transformers.
Transformers designed for frequencies other than 50 hertz.
Gas-filled dry-type transformers.
Flameproof transformers.

Technical requirements

For technical requirements regarding distribution transformers, including testing requirements and Minimum Energy Performance Standards, review the relevant Determination and standards.

Standards

The following standards are referenced in this Determination and are available for purchase from Standards Australia.

AS 2374.1-1997 Power transformers Part 1: General, as it existed on 5 September 1997 (although this standard has been superseded by AS/NZS 60076.1:2014, it is still used for the purposes of this Determination).
AS 2374.1.2-2003: Power Transformers Part 1.2: Minimum Energy Performance Standard requirements for distribution transformers, as it existed on 26 October 2012.
AS 2735-1984: Dry-type power transformers, as it existed on 9 November 1984

Minimum Energy Performance Standards

The Minimum Energy Performance Standards, set out as minimum power efficiency levels at 50 per cent of rated load for various transformer types, are outlined below.

For more information, please see Table 1 and Table 2 at Clause 2.1 of AS 2374.1.2-2003.

Minimum power efficiency levels

Minimum power efficiency levels for oil-immersed transformers

Type	kVA	Power efficiency @ 50% load
Single phase (and SWER)	10	98.30
	16	98.52
	25	98.70
	50	98.90
Three phase	25	98.28
	63	98.62
	100	98.76
	200	98.94
	315	99.04
	500	99.13
	750	99.21
	1000	99.27
	1500	99.35
	2000	99.39
	2500	99.40

NOTE: For intermediate power ratings the power efficiency level shall be calculated by linear interpolation.

Minimum power efficiency levels for dry type transformers

Type	kVA	Power efficiency at 50% load
		Um = 12 kV	Um = 24 kV
Single phase (and SWER)	10	97.29	97.01
	16	97.60	97.27
	25	97.89	97.53
	50	98.31	97.91
Three phase	25	97.17	97.17
	63	97.78	97.78
	100	98.07	98.07
	200	98.46	98.42
	315	98.67	98.59
	500	98.84	98.74
	750	98.96	98.85
	1000	99.03	98.92
	1500	99.12	99.01
	2000	99.16	99.06
	2500	99.19	99.09

NOTE: For intermediate power ratings the power efficiency level shall be calculated by linear interpolation.

High Power Efficiency Transformers

Minimum efficiency levels for products to be classified as ‘High Power Efficiency Transformers’, set out as minimum power efficiency levels at 50 per cent of rated load, are outlined below for various transformer types.

See Table 3 and Table 4 at Clause 3.1 of AS 2374.1.2-2003 for detailed conditions and test methods.

High power efficiency levels

High power efficiency levels for dry-type transformers

Type	kVA	Power efficiency at 50% load
		Um = 12 kV	Um = 24 kV
Single phase (and SWER)	10	97.53	97.32
	16	97.83	97.55
	25	98.11	97.78
	50	98.50	98.10
Three Phase	25	97.42	97.42
	63	98.01	98.01
	100	98.28	98.28
	200	98.64	98.60
	315	98.82	98.74
	500	98.97	98.87
	750	99.08	98.98
	1000	99.14	98.04
	1500	99.21	99.12
	2000	99.24	99.17
	2500	99.27	99.20

NOTE: For intermediate power ratings the power efficiency level shall be calculated by linear interpolation.

High power efficiency levels for oil-immersed transformers

Type	kVA	Power efficiency at 50% load
Single phase (and SWER)	10	98.42
	16	98.64
	25	98.80
	50	99.00
Three Phase	25	98.50
	63	98.82
	100	99.00
	200	99.11
	315	99.19
	500	99.26
	750	99.32
	1000	99.37
	1500	99.44
	2000	99.49
	2500	99.50

NOTE: For intermediate power ratings the power efficiency level shall be calculated by linear interpolation.

Testing your product

Products must be tested in accordance with section 4 of AS 2374.1.2-2003 and section 5 of AS 2735-1984.

Labelling Requirements

This product is not required to display an Energy Rating Label, but there are requirements for rating plates.

Each transformer’s rating plate must contain a statement that the transformer complies with AS 2374.1.2.

Useful resources

Access to standards

Complete national and international standards can be purchased online within Australia

Energy Rating Registration Database

Registered products can be viewed using the Energy Rating Registration Database.

Registering a product

Read more about the registration process and requirements for these products.

Consultation Regulation Impact Statement Update

A Regulation Impact Statement for Distribution Transformers was released for public consultation on 14 October 2024 (this is referred to as a consultation regulation impacts statement or CRIS). This consultation period closed on 31 January 2025 after it was extended following a request for additional time.

The CRIS examines options for expanding the scope of regulations and raising the minimum energy performance standards (MEPS), which are governed under the Greenhouse Energy Minimum Standards Act 2012.

Public information sessions were held in mid-November 2024, including a joint session for Australia and New Zealand on 12 November, which focused on the technical aspects of the CRIS. Policy forums were also held in both countries for government agencies and Electricity Distribution Service Network Providers to discuss policy implications of the proposed MEPS.

The consultation period closed with a total of 18 submissions received, including 10 from Australia and 8 from New Zealand. Only written submissions from Australia will be made publicly available on the Department of Climate Change, Energy, the Environment and Water’s website.

Submissions from manufacturers and suppliers indicated that there may be more significant industry consequences and concerns than were assumed in the CRIS.

Concerns around the cost and accessibility of materials required to manufacture Distribution Transformers with an improved energy efficiency were raised. Along with requests to review assumptions in the CRIS including considering how transformers are installed and tested in the field.

Detailed costings and other data have been provided by manufacturers and will be incorporated into revised cost benefit modelling.

The policy recommendations in the CRIS will be reviewed before drafting a Regulation Impact Statement for Decision (DRIS). It is expected that the DRIS will be prepared for submission to the Commonwealth, State, Territory, and New Zealand Energy Ministers in the second half of 2025.