Chassis Mounting Autowound Toroidal Transformers Technical Notes


1. Chassis mounting Auto wound Transformer

  • The  AT range of Chassis mounted transformers are available  in wide range of input and output voltages and power ratings  415v 400v 380v 240v 230v 220v to 120v 115v 110v 100v
  • Auto transformers can be used to step-up or step-down for example a “0-110-230v” transformer may be used to covert  110v to 230v (step-up)   or covert  230v to 110v (Step-down)
  • Operating frequency’s ranging from 50Hz to 400Hz however it should be noted that a transformer will not change the frequency the output frequency will be the same as the input frequency.
  • British Built high quality Auto wound toroidal transformers
  • Ideal for secure power conversion on the shop floor
  • In addition to our standard range, we will be pleased to quote for your special requirements
  • Temperature All our transformers are designed to run at a max of 60degC above ambient.
  • Manufactured to Class A 105degC
  • RoHS Compliant

Chassis Mounting Auto Toroidal Transformer

2. Why and where used

Autotransformers have the advantages of often being smaller, lighter, and cheaper than typical dual-winding transformers, but autotransformers have the disadvantage of not providing electrical isolation.

Autotransformers are often used to step up or step down voltages in the 110-115-120 volt range and voltages in the 220-230-240 volt range—for example. Providing 110 or 120V (with taps) from 230V input, allowing equipment designed for 100 or 120 volts to be used with a 230 volt supply (as in using US electrical equipment with higher European voltages


3. What is an Auto Transformer?

An autotransformer (sometimes called auto step down transformer)is an electrical transformer with only one winding. The "auto” prefix refers to the single coil acting on itself and not to any kind of automatic mechanism In an autotransformer, portions of the same winding act as both the primary and secondary sides of the transformer. The winding has at least three taps where electrical connections are made.

The Toroidal construction of an auto-transformer offers important advantages in comparison with an E/I lamination core transformer, like smaller physical size and weight, 30-70% reduction (depending on secondary voltage) and very low magnetic stray fields. The auto-transformer can be mounted horizontally using a steel washer or an epoxy potted centre with a mounting hole

4. Wiring circuit diagram

Chassis mounting auto diagram

Auto transformers can be used to step-up or step-down for example a “0-110-230v” transformer may be used to covert  110v to 230v (step-up)   or covert  230v to 110v (Step-down)


Colour Code

0-110-230 Blue Black Brown

0-115-230v Blue Black Brown

0-120-230 Blue Black Brown

0-110-415 White Black Red

0-230-415 Blue Black Red

Auto transformer share the same neutral usually the Blue

5. Installation notes

As an auto transformer both the input and output share a common neutral and earth.


6. Quality Control

All transformers manufactured by Airlink Transformers have been subject to the BS EN ISO9001:2008 management standards

Conforms BSEN61558-2-13 CE & RoHS

Airlink Transformers – a leading, UK based toroidal transformer manufacturer and seller.

Custom wholesale orders

As a design and manufacturing company, we are able to custom build transformers to suit your exact specification. Service available for larger orders with an initial prototype.

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