A METHOD TO COMPENSATE PRE-ARCING TIME IN SF6 GAS CIRCUIT BREAKERS

摘要

determining a breakdown voltage (BDV) value for each gap value through the formula. BDV=E critical/ E max * V , wherein. V being a preset input line voltage (V). E critical being electric field value within the circuit breaker corresponding to said SF6 gas pressure value within the circuit breaker and E max being a maximum electrical stress value (E max) amongst the electrical stress value measured on the stationary and moving main & arcing contacts at each gap value between the stationary and moving arcing contacts, thus each BDV value corresponding to a time value; plotting a graph of a breakdown voltages (Y-axis) versus their corresponding time values (X-axis); plotting a modulus sine wave of the input line voltage on the said graph; determining a first time value which being the time value on the X-axis of said graph corresponding to the point of intersection of the breakdown voltage curve and the modulus sine wave; determining a second time value which being the time value on the X-axis of said graph corresponding to the point of intersection of the breakdown voltage curve and the X-axis; and subtracting the first time value from the second time value, the result of which being the pre-arcing time corresponding to said SF6 gas pressure value within the circuit breaker. (Fig I)