Autotransformer

An autotransformer differs from a conventional two-winding transformer in one fundamental way: instead of using fully separate primary and secondary windings, it uses a single winding with a shared section serving both the input and output. This design uses less conductor material and can make the transformer smaller, lighter, and more cost-effective than an equivalent two-winding isolation transformer, while still providing voltage step-up or step-down through electromagnetic induction.

PowerHome autotransformers are three-phase dry-type units available from 1 kVA to 100 kVA for fixed industrial voltage matching. Standard and custom configurations are available for common three-phase systems including 200V, 220V, 230V, 240V, 380V, 400V, 415V, and 480V, supporting both step-up and step-down applications. They are suitable for matching the available site supply voltage to the voltage required by compatible industrial equipment, control systems, motor-driven machinery, and generator-fed loads.

Self-cooling and wind-cooled options are available, along with copper or aluminum windings and open-type or sealed enclosure configurations. Designed for AC 50Hz or 60Hz systems, these autotransformers provide high-efficiency fixed voltage conversion while maintaining the incoming frequency. They are a practical solution for industrial machinery, automation equipment, control panels, pumps, fans, conveyors, packaging systems, and generator voltage matching where galvanic isolation between input and output is not required. Custom voltage and capacity configurations are available on request.

Three-Phase Autotransformers for Motor Voltage Matching

PowerHome three-phase autotransformers are designed to match the available industrial supply voltage to the rated line voltage of compatible three-phase motors and motor-driven equipment. Select a fixed step-up or step-down configuration for 200V, 220V, 230V, 240V, 380V, 400V, 415V, or 480V power systems.

These dry-type autotransformers change voltage while maintaining the incoming frequency. They are suitable when the supply voltage and motor nameplate voltage differ, but the motor phase, frequency, and operating requirements are compatible.

Important: This product is a fixed-ratio voltage-matching autotransformer. It is not an autotransformer motor starter, soft starter, VFD, phase converter, voltage stabilizer, or isolation transformer.

Typical Equipment and System Applications

PowerHome three-phase autotransformers are used for fixed voltage matching in industrial motors, pumps, fans, blowers, conveyors, mixers, packaging machines, machine tools, automation equipment, control panels, generator-fed systems, and imported industrial machinery.

They are suitable when the required equipment voltage differs from the available three-phase supply voltage and galvanic isolation is not required.

Common Three-Phase Motor Voltage Matching Applications

Select an autotransformer when the available three-phase supply voltage differs from the voltage required by a compatible motor or motor-driven machine.

Note: These autotransformers provide fixed voltage conversion only. Confirm the motor nameplate voltage, phase, frequency, full-load current, starting method, and required kVA before ordering. They do not change frequency, provide electrical isolation, or replace a motor starter, soft starter, or VFD.

How to Select a Three-Phase Autotransformer

To select the correct autotransformer, confirm the available site voltage, required equipment voltage, phase, frequency, and load current before ordering.

After confirming the input voltage, required output voltage and maximum load current, calculate the required load capacity using the three-phase kVA formula. For a balanced three-phase load: kVA = √3 × Output Voltage × Output Current ÷ 1000. See our guide on how to size a three-phase autotransformer for a worked calculation example and guidance on motor starting current, simultaneous loads, VFDs, harmonics and sizing margins.

Need help sizing? Send us the equipment nameplate photo, supply voltage, required output voltage, load current, frequency, and operating conditions for a configuration recommendation.