S220B is more than an electric power meter. Combining the functions of a clamp meter, phase sequence detector, and digital power meter, it is an ideal instrument for efficient power quality inspections. Not only can it be used for measurements of frequency, phase sequence, voltage, current, the phase between voltages, the phase between currents, and phase between current and voltage of a 3 phase AC system, it can also be used to measure active power, reactive power, apparent power, power factor, current vector and, identify vector group of transformers, differentiate inductive and capacitive circuits, test the secondary circuit and differential busbar protection systems, determine the phase relationship between the differential protection CT groups and verify the configuration of the watt-hour meter.