3~10kV电动机-电流速断保护整定计算

                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  3~10kV电动机－电流速断保护整定计算

一、计算条件

    可靠系数：Krel=1.32

    接线系数：Kjx=1

    电动机起动电流倍数：Kst=7

    电流互感器变比：nTA=15

    电动机额定电流：IrM=35.9(A)

    最小运行方式下，电动机接线端两相短路时，流过保护安装处的超瞬态电流：I"k2·min=7000(A)

二、计算公式及结果

    保护装置的动作电流：

    异步电动机（应躲过电动机的起动电流）：

    Iop·K=Krel*Kjx*Kst*IrM/nTA

          =1.32*1*7*35.9/15

          =22.1144(A)

    保护装置的灵敏系数（按最小运行方式下，电动机接线端两相短路时，流过保护安装处的短路电流校验）：

    Ksen=I"k2·min/Iop=I"k2·min*Kjx/(Iop·K*nTA)

        =7000*1/(22.11*15)

        =21.1≥2

    保护装置的灵敏系数大于等于2，符合要求！