高压电动机负序过电流保护整定计算

分析、计算了各种运行情况下电动机的负序电流,分析了各种运行方式下出现负序电流对电动机的危害,粗略估算了各种运行方式下出现负序电流的允许时间,并分析了各种运行方式下正序电流与负序电流、负序功率方向的关系,指出无负序功率方向闭锁负序过电流时常用整定值存在的问题,在区外不对称短路时易引起误动。对不同负序过电流保护动作判据、不...

Setting Calculation of Negative Sequence Overcurrent Protection for High-voltage Motor

Motors’ negative sequence(NS) current calculation and its harms for motors under various operation conditions are analyzed.Allowance time of NS current appeared under different operational conditions are roughly calculated.Relationship between positive sequence current and NS current,and relationship between positive sequence current and NS power direction are also analyzed.Problems existing in frequently used settings for blocking NS overcurrent without involving NS power direction are pointed out and it is easy to cause mal-operation when off-site asymmetric short-circuit fault occurs.Proper settings calculation methods for different NS overcurrent protection acting criteria and different protection functions are given.Satisfactory protection function can be obtained for the stator windings two-phase short-circuit of high-voltage motors by adopting NS overcurrent protection with NS power direction blocking as the auxiliary protection for the stator windings two-phase short-circuit of the high-voltage motors.