Custom Autoformers are designed to provide system power

Autoformers are products with no isolation between input and output windings. This may be a favorable option when there is already system isolation provided in the electrical circuit. Autoformers can be designed smaller and are less expensive than isolated transformers due to decreased material, size and manufacturing times.

While having no isolation, Autoformers can retain many of the useful features or options of General Purpose, Power or other types of units:

  • Either Step-Up or Step-Down,
  • Single-phase and three-phase,
  • Multiple primary or secondary voltages accommodated,
  • Available open frame or in a NEMA rated enclosure with a host of available options
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Below are examples of some of the different models we have built for customers:

6.3kVA General Purpose Transformers MT-4662 75kVA autoformer 3PH, 40-1,000Hz Input = 208/120Vrms Output = 3x outputs 15kVA General Purpose Transformers MT-4545 225kVA autoformer 3PH, 40-500Hz 4 inputs 4 outputs Custom General Purpose Transformer with multiple taps MT-3908 1.674MVA autoformer 3PH, 60Hz Input = 600V wye Output = 630/660/690Vrms wye 22kVA General Purpose Transformer MT-3787 578kVA autoformer 3PH, 60Hz Input = 600Vrms Output = 630Vrms MT-3647 777kVA autoformer 3PH, 60Hz Input = 600Vrms wye Output = 630/660/690Vrms wye

Standard Specification Ranges

Auto transformers can be specified much like a General Purpose or Power Transformer. Voltage, frequency, number of phases, input and output voltages and currents as well as connection types, enclosures, safety devices and other options are all available as part of the specification. Autoformers can also be utilized as part of an electrical assembly

Power Rating 50VA up to 1.5MVA
No. of Phases 1
Frequency 50/60Hz
400Hz up to 20kHz
Voltages Up to 600V Standard
Other Options Enclosures
Circuit breakers
EMO switches
Low impedance
K-factor rating

Our Autotransformers

Often being smaller and less expensive than units with isolation between primary and secondary windings, Autoformers can be a good option when isolation is already provided in the circuit and is not necessary in the transformer itself. The option remains to include this type of product as part of an assembly and all the standard options for an isolated transformer exist for an autoformer, except of course the isolation.