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Distribution transformers

Modern new power station

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.

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