An offset is the mean amplitude of a periodic function waveform in the time domain. The existence of offsets in electrical power sinusoidal signals leads to inaccurate measurements of all electrical power parameters. Each component in a measurement instrument may cause offsets. For example, offsets may appear in a hall-effect transducer because of the condition of temperature or the magnetization state of a magnetic circuit. Intense solar flares can cause a strong electromagnetic field, which leads to offsets in an electrical power grid.

To calibrate offsets, you first use a standard signal generator to generate sinusoidal signals with zero offset and then use the measurement instrument to measure the sinusoidal signals. You get the offset values by comparing the measured results with the standard sinusoidal signals. In future measurement, you subtract the offset values from measured results to ensure accurate measurements.