Equivalent impedance measurement system for AC electricity network - applies dummy load over waveform periods to obtain sum of inductive and resistive impedances and resistance only

摘要

This process is used to measure the resistive and inductive part of the impedance of the AC electricity grid under steady conditions. It can directly determine the characteristics of fault loops in the industrial frequency low voltage electricity grid. A resistive load (R) is applied between the terminals (A,B) of the grid whose characteristics are unknown. The mean value of the voltage (V) at the terminals (A,B) of the grid is measured for a period including part or all of the time during which the load (R) is applied. The limits (TO,T2;T'O,T'2) of two integration periods are chosen to give two results, one of which is proportional to the sum of the resistive and inductive part (r+L'omega') of the impedance and the other is proportional to the resistive part (r) only.