电炉变压器的保护定值计算

Arc Furnace Transformer Protection Setting Value Calculation

电炉冶炼熔化期电极及炉料或电极周围的炉料塌落而使电极二相或三相短路。电炉变压器在熔化期点弧及塌料时经常处于连续短路状态,这种工作短路是不可避免的,是正常现象。所以电炉变压器必须满足这一要求,但又必须采取措施,使工作短路电流的倍数和持续时间不超过规定值。根据冶炼工艺的要求和电炉电气设备标准规定,工作短路电流要小于3～3.5倍电炉变压器额定电流,持续时间小于6s,短路速断电流小于4～6倍电炉变压器的额定电流,持续时间0s。

Two phase or three - phase short - circuit took place often during electric smelting period a- round electrodes because of burden collapsing. The condition of short - circuit continuous short - cir- cuit is inevitable and normal. So the arc furnace transformer is supposed to meet the requirement, and must adopt measures to make times of short - circuit current ratio in proper range. According to requirements of electric smelting process and electrical equipment standard, working short - circuit current is less than 3 - 3.5 times rated current arc furnace transformer, with duration less than 6s, short - circuit current quick break less than 4 - 6 times rated current of the arc furnace transformer and the duration 0s..