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Transformer glossary

What are the different types of transformers?

There are multiple transformer types available that can be utilized for countless different applications across a wide range of industries. This includes sensitive electronic equipment, heavy-duty industrial machinery, and low and high voltage requirements. The different types of transformers include:

  • Autotransformers 
  • General purpose transformers 
  • Industrial control transformers 
  • Isolation transformers 
  • Medium voltage control transformers 
  • Military transformers 
  • Power transformers 
  • Step down transformer 
  • Step up transformer 
  • Single phase transformer 
  • Three phase transformer 
  • Distribution transformer 
  • Current transformer 
  • Potential transformer 
  • Instrument transformer 
  • Air Core transformer 
  • Iron core transformer 
  • Ferrite core transformer 
  • Toroidal core transformer 
  • Grounding or earthing transformer 

Understanding the different transformer types is paramount to knowing which transformer will work best for your specific applications.


Utilized for both step-up and step-down applications, autotransformers contain only one winding, with a portion of the coil serving as both the primary and secondary winding. Available in three-phase and single-phase models, autotransformers are typically used in low-voltage situations of 600 volts or less. Autotransformers are perfect for low voltage applications, such as induction motor starters, and are often utilized when the incoming voltage needs to stepped up or down in only small increments.

Industrial control transformers/Industrial power transformers

Industrial control transformers change supply voltages for electromagnetic devices such as contractors, solenoids, relays and timers. Upon start up, most electromagnetic devices require anywhere from 3 to 10 times their normal operating current for 30 to 50 milliseconds. SNC’s single- and three-phase industrial control transformers provide the high degree of secondary voltage stability required for that period, accommodating the momentary current inrush caused upon start up. Industrial control transformers are the same as a control power transformer but are different from a general power/general purpose transformer.

Isolation/insulation transformers

An isolation transformer is a transformer with a separation/barrier between the primary and secondary windings. The physical separation of the primary and secondary windings allows an AC signal to be taken from one device and fed into the other, without having the two circuits electrically connected.

An “insulating transformer” is the same as an isolation transformer, as the terms isolating and insulating are interchangeable and do not indicate two separate transformers types. Available in three-phase and single-phase models, isolation/insulating transformers contain two symmetrical windings and transform all the incoming voltage, rather than a portion of it. 

Medium voltage control transformers

Medium voltage control transformers are single-phase transformers designed and constructed to address industrial control application demands. Medium voltage is typically defined as containing a power supply rating anywhere from 5 kV to 35 kV and medium voltage control transformers are utilized for stepping down medium voltage to a lower voltage.

Engineered with a medium voltage primary winding and a secondary winding consisting of either a 120VAC, 60 Hz or 110VAC, 50 Hz, medium voltage transformers must comply with the IEEE (Institute of Electrical and Electronics Engineers) and IEC (International Electrotechnical Commission) standards. 

Military transformers 

Built to meet stringent military standards, military transformers change supply voltages for operating components in airborne, space, missile, shipboard and other military applications. 

Step-up and step-down military transformers contain a dual frequency rating for 50/60 Hz, offer the ability to receive input power that ranges from 115 to 600 volts and deliver output power that ranges from 23 to 240 volts.

While there are additional requirements that certain military transformers must meet depending on application and specs, SNC’s military transformers can comply with the rigid ITARs and DFARs requirements, as well as the MIL-PRF-27 and MIL-STD-202 requirements. 

Power transformers

A power transformer equates to a transformer that is powering up an application, rather than powering down or stepping the voltage down. Available as single-phase and three-phase transformers, power transformers are step-up transformers utilized for applications that require a voltage that’s higher than the incoming voltage.

Different transformer types, explained

Your particular applications and industry require a specific transformer type. Understanding the different types of transformers is crucial to top productivity and safety. If you have questions about SNC’s different transformer types, contact us today.