Autotransformer vs Isolation Transformer

An isolation transformer is an electrical transformer with a primary and secondary coil winding. These windings are separated by insulation. This insulation limits the risk of electrocution when the active parts and earth are touched simultaneously.

An autotransformer is an electrical transformer with only one winding. The term “auto” refers to a single coil acting alone, 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.

Operation of an Isolation Transformer

The primary purpose of an isolation transformer is to isolate circuits. These transformers are designed and manufactured with attention to capacitive coupling between the two windings. Capacitance between primary and secondary windings would also couple alternating current (AC) current from the primary to the secondary.

Operation of an Autotransformer

The primary purpose of an autotransformer is to regulate the voltage of transmission lines and can be used to transform voltages. With only one winding, an autotransformer adjusts the voltage automatically according to load. These transformers call for AC currents to operate correctly and will not function on direct current.

Common Applications for an Autotransformer

• Boost at end of long transmission line to compensate for line losses
• Reduced starter voltage for an induction motor
• To enable rectifier output control, multi-tap feeding the primary
• Fluorescent light fixture start-up

Common Applications for an Isolation Transformer

• Computers and peripherals
• Medical Equipment
• Remote control equipment
• Telecommunication equipment

Contact Badger Magnetics today for an evaluation of your specific transformer needs, whether it is an isolation transformer vs an autotransformer.

Badger Magnetics is the leading electromagnetic transformer manufacturer.