Sizing Distribution and Buck Boost Transformers
Sizing Dry Type Distribution Transformers for Three Phase Loads:
1. Determine the load by getting the following information from equipment nameplates or instruction manual.
- Voltage required by load.
- Amperes or kVA required by load.
- Frequency in Hz (cycles per second).
The frequency of the electrical load MUST match the line supply. - Verify load is designed to operate on three phase.
2. Determine the supply voltage.
- Voltage of supply (source).
- Frequency in Hz (cycles per second).
The frequency of the line supply MUST match the electrical load.
3. Select a transformer with a standard kVA capacity equal to or greater than that needed to operate the load.
- Primary taps are available on most models to compensate for line voltage variations.
- When load ratings are only available in amperes, the following formula may be used to determine
proper kVA size for the required transformer:
Three Phase kVA = Volts x Amps x 1.73
1000
Sizing Buck Boost Transformers for Three Phase Loads:
The following information needs to be determined before selecting which buck boost transformer for a phase converter (or any other application) is required:
- Line Voltage: The voltage that you want to buck (decrease) or boost (increae) can be measured with a voltmeter at the supply line voltage.
- Load Voltage: The voltage at which your equipment is designed to operate is listed on the nameplate of the load equipment.
- Load kVA or Load Amps (not both): The sum of all the equipment that represents the load can usually be found on the nameplate of the load equipment.
- Frequecy: This frequency must be the same as the equipment to be operated (50 or 60Hz)
- Phase: The supply line should be the same as the load (single-phase or three-phase). When used with an American Rotary phase converter, the buck boost transformer is installed between the supply line and the phase converter, requiring a single-phase buck boost transformer.
