Waveform Data Logging (Electrical Power Toolkit)

Waveform data is useful for the analysis of power quality, system faults, motor initialization, breakers, and timing.

Waveform data typically is resampled raw voltage and current values in the cycle domain for analog input channels. For digital channels, waveform data is the status of relay switches. Waveform data logging starts when an analog input signal crosses a trigger threshold or when a digital input channel changes its state. You also can manually start waveform data logging.

Waveform data usually contains pre- and post-fault data, which are values logged for several cycles before and after a trigger fires. Pre- and post-fault data are useful in determining the causes and effects of faults. By default, the LabVIEW Electrical Power Toolkit samples data at 192 samples per cycle. However, because the system frequency synchronizes with the sample rate, the number of samples per second may change as the system frequency changes. A higher sample rate ensures a more accurate description of a system. Because logged waveform data usually contains hundreds of samples acquired over one second, you need to take the amount of system memory into consideration. For example, data logged at 256 samples per cycle for a 50 Hz system occupies 102.4 KB system memory every second.