General-Purpose Transformers

Shop general-purpose transformers used for voltage conversion and electrical isolation in industrial and commercial electrical systems. Available products may include single-phase and three-phase dry-type transformers in ventilated, enclosed and non-ventilated constructions.

Compare transformers by primary and secondary voltage, phase, frequency, kVA rating, enclosure type, winding material and temperature rise. Confirm that the transformer is suitable for the connected load, installation environment and applicable electrical requirements.

How to Select a General-Purpose Transformer

General-purpose transformers are used to step voltage up or down and may provide electrical isolation between the supply and connected load. They are commonly installed in commercial buildings, industrial facilities, machinery and electrical-distribution systems.

Selection begins with the available source power and the voltage required by the load. The transformer must also be sized for phase, frequency, continuous kVA demand, enclosure conditions and any applicable installation requirements.

Important Selection Factors

• Primary voltage: Match the available incoming power and required winding connection.
• Secondary voltage: Confirm the voltage required by the connected equipment or distribution circuit.
• Phase: Use a single-phase or three-phase transformer that matches the electrical system and load.
• kVA rating: Size the transformer for the continuous connected load and appropriate design margin.
• Frequency: Verify compatibility with the available supply frequency.
• Winding configuration: Confirm the required primary and secondary connections, taps and neutral arrangement.
• Enclosure: Select ventilated, non-ventilated or encapsulated construction suitable for the installation.
• Winding material: Review copper or aluminum winding requirements when specified.
• Temperature rise and efficiency: Consider operating temperature, losses and applicable efficiency requirements.

Single-Phase vs. Three-Phase Transformers

Single-phase transformers are commonly used for smaller equipment loads, lighting, receptacles and control applications. Three-phase transformers support three-phase distribution and equipment loads. The transformer phase must match the source and intended load configuration.

Replacement Checklist

• Manufacturer and complete model number
• Primary and secondary voltage
• Single-phase or three-phase supply
• kVA rating
• Frequency
• Winding connections and available taps
• Enclosure type and environmental requirements
• Mounting dimensions and available installation space
• Photographs of the nameplate and connection diagram