Autotransformer Rating Calculator

How Autotransformer Rating works

This worksheet evaluates VA = Vload × Iload. Autotransformer Rating uses Load voltage, Load current to report Transferred apparent power.

With the loaded values, transferred apparent power evaluates to 1,800.00 VA. Hold the remaining entries steady while testing an uncertain input.

Inputs for Autotransformer Rating

Load voltage and Load current belong to Autotransformer Rating. Keep source units with load voltage.

Use the defaults to understand the output, then enter the real circuit or energy data.

Load voltage

Example entry: 120 V.

Load current

Example entry: 15 A.

Reading the Autotransformer Rating result

This output represents Autotransformer Rating.

Apply required margins only after identifying the correct equipment standard.

Measurement and units

Check component ratings, isolation requirements, temperature, waveform, and manufacturer limits. Check prefixes on load voltage. Ideal duty cycle belongs in the separate Converter Duty Cycle worksheet.

Alternatives should share one documented measurement convention.

Limits of this calculation

An autotransformer does not provide galvanic isolation.

Unlisted circuit behavior remains outside the computed result. Unentered effects remain outside Autotransformer Rating. For apparent power, use Transformer VA Rating Calculator.

A useful Autotransformer Rating comparison

Record transferred apparent power before testing a different load voltage value.

Document the alternate load voltage source.

Questions about Autotransformer Rating