Measuring all three phases of a power system is important because it provides a more complete understanding of the system’s behaviour. A three-phase system is a type of electrical power system that uses three separate conductors to supply power to loads. Each conductor carries a sinusoidal voltage waveform that is 120 degrees out of phase with the others. By measuring all three phases, it’s possible to determine the total power consumed or generated by the system, as well as the power consumed or generated by individual loads. In addition, by measuring all three phases, it is possible to detect any imbalances or problems within the system, such as a fault on one phase, which could indicate a problem that needs to be addressed.