Measurement and Correction of No-Load Losses of Power Transformers

The paper reviews the practice of correcting the results of no-load loss measurements of large power transformers for the effect of distorted supply voltage waveforms. Data obtained during testing of large power transformers are reproduced and analyzed at the National Research Council laboratory to ensure that the proper corrected losses are determined. The instrumentation requirements for no-load loss measurements, particularly when the transformers under tests are energized line to line are discussed