Protective relaying system

摘要: Protection of an electric power system is attained under control a digital computer. Voltage and current the to be protected are subjected sampling at predetermined frequency applied computer after being converted into signals. The computes product these two signal inputs. thus obtained added preceding representing voltage taken time before period so that unnecessary components included in signals can removed. Then, level resultant (which free from components) compared with reference signal. When former greater than latter, there fault system, necessary protective measures protect system.