Frequency is the number of cycles per second in an AC waveform. Synchronous generators provide electrical power to an electrical power grid and the rotational speed of synchronous generators determines the line frequency. AC electrical power transmits across electrical power grids at a line frequency of 50 Hz or 60 Hz. The advantage of having a standardized frequency is that multiple generators can connect to one grid and operate in parallel.

The LabVIEW Electrical Power Toolkit complies with IEC 61000-4-30:2008 for frequency measurement. The Electrical Power Toolkit specifies to measure frequency values every 10 second and the measurement periods are non-overlapping. The Electrical Power Toolkit discards a cycle if variations in the fundamental frequency cause the individual cycle to overlap a real-time clock (RTC) 10 seconds tick. Because multiple zero crossings cause frequency distortions, the Electrical Power Toolkit attenuates harmonic and interharmonic frequency components prior to measuring the fundamental frequency in order to minimize frequency distortions.