Indotech Digital Watt Meter – Indotech digital watt meter samples the voltage and current thousands of times a second. For each sample, the voltage is multiplied by the current at the same instant; the average over at least one cycle is the real power. The real power divided by the apparent volt-amperes (VA) is the power factor. A computer circuit uses the sampled values to calculate RMS voltage, RMS current, VA, power (watts), power factor, and kilowatt-hours. The readings may be displayed on the device, retained to provide a log and calculate averages, or transmitted to other equipment for further use.

Indotech digital Watt meter vary considerably in correctly calculating energy consumption, especially when real power is much lower than VA . Simple meters may be calibrated to meet specified accuracy only for sinusoidal waveform. Wave-forms for switched-mode power supplies as used for much electronic equipment may be very far from sinusoidal, leading to unknown and possibly large errors at any power. This may not be specified in the meter’s manual.