[گلاویژ]

In accordance with ANSI Code , 51 means overcurrent function . When it is combined with ” V” , it means restranit voltage overcurrent. It is used for earth fault currents very close to generator . it is probable , despite earth fault occurring close to generator , because of high synchronous reactance the current to be low and not detected by current relays . 51 V is a function which detects the ratio of current over voltage . In this condition the voltage is also low , but the ratio is enough high to be detected by 51V .