Imported Electricals? You Need Auto Transformers


Auto transformers are single winding transformers that are useful where isolation from the mains supply is not required.

Southern Electronic Services can design and supply custom auto transformers to importers of electrical equipment, or electrical contractors installing imported equipment. They are ideal for adapting imported equipment to Australian power (single-phase 240v 50Hz, or three-phase 415v 50Hz).

If you have electrical equipment from overseas that is designed to operate on a voltage different to Australian power (single-phase 240v 50Hz, or three-phase 415v 50Hz), we can provide the correct autotransformers. Save yourself the expense of having imported electrical equipment rewound to operate from Australian power. Suitably rated autotransformers remove the need to have equipment rewound, or the need to purchase a more expensive isolation transformer.

Australian Standard AS3000 (Clause 4.28.4) requires autotransformers that change voltage by more than 25 percent to be an integral part of the equipment they are powering. Hardwiring the equipment to the output of the autotransformer achieves this requirement.


Advantages of SES Auto Transformers

We can manufacture and supply both “single phase” and “three phase” auto transformers – as well as friendly advice to assist with your particular application.

Our auto transformers feature:

  • Australian Standard AS60076-2005 compliant
  • Available in a wide power range – from 10VA to 500 KVA
  • Insulation classes up to class H – 180°C
  • Fast turnaround for a custom transformer – often within days
  • Robust construction
  • Available as open type with flying leads or terminal blocks
  • Choice of mounting brackets
  • Tough varnish coating in either clear or black
  • For hard wiring can be encased in a powder-coated steel (IP23) enclosure

Smaller, Lighter & Cheaper

Auto transformers are smaller, lighter and more economical than isolation transformers of the same power.

For example, a three-phase auto transformer to power equipment rated at 200v 10KVA (imported from Japan) would be about half the size and weight of an equivalent isolation transformer. Even greater savings can be achieved using an auto transformer if the input and output voltages are closer together – e.g. single phase 240v / 220v or three phase 415v / 380v.

Tips for Using Auto Transformers

  • They do not provide isolation from the electrical supply.
  • They are only suitable when the ratio of input/output is less than about two. Single phase 240v input / 100v is the lowest viable output voltage. Similarly, three phase 415v input / 200v output is the lowest viable output voltage.
  • They can be used for step up as well as the more common step-down applications.
  • They always have a common terminal. This may be connected to the neutral of the input supply (never the active), or left un-connected.
  • Take care to ensure that any imported equipment will operate at a power frequency of 50Hz. Some imported equipment (e.g. motors) may be rated at 60Hz only (as opposed to 50-60Hz) and may overheat if operated at 50Hz, even with the correct voltage applied.

Get a Custom Transformer in Days

We stock a wide range of components and enclosures so that we can produce custom-made autotransformers with short notice.

Talk to Southern Electronic Services Today

To discuss your requirements for autotransformers
CALL 03 9706 4202