为了确定装置中的短路电流，应考虑故障点以及大化涉及装置的短路电流的系统配置。如适用，应考虑电机的贡献。例如，在下文详述的情况下，对于断路器CB1，坏的情况发生在故障位于断路器本身的正上游时。为了确定断路器的开断能力，必须考虑两个并联变压器的贡献。CB1的右下游故障CB1的右上游故障（CB1的坏情况）一旦确定了故障点处的短路功率当量，可以使用以下公式计算短路电流：三相短路两相短路6.3.3计算短路电流以确定装置中的短路电流，应考虑故障点和系统配置，以大化涉及装置的短路电流。如适用，应考虑电机的贡献。例如，在下文详述的情况下，对于断路器CB1，坏的情况发生在故障位于断路器本身的正上游时。为了确定断路器的开断能力，必须考虑两个并联变压器的贡献。CB1的右下游故障CB1的右上游故障（CB1的坏条件）6.3短路电流的确定：“短路功率法”492电气设备| ABB 6短路电流的计算SkEL Ik SkUP SkUP=°SkUP=1000 MVA SkUP=750 MVA SkUP=500 MVA SkUP=250 MVA SkUP=100 MVA SkUP=50 MVA SkUP=40 MVA SkUP=30 MVA SkUP=20 MVA SkUP=10MVA SkEL[MVA]Ik[kA]0 10 20 30 50 60 70 80 90 100 120 130 150 0 10 20 30 40 60 80 90 100 1SDC010052F0001作为一级近似值，通过使用下图，可以评估已知短路功率（SkEL）的物体下游的三相短路电流；与该值对应，在知道物体上游短路功率（SkUP）的情况下，可以在y轴上读取Ik的值，以kA表示，电压为400 V。图1：三相短路计算图

To determine the short-circuit current in an installation, both the fault point as well as the configuration of the system which maximize the short-circuit current involving the device shall be considered. If appropriate, the contribution of the motors shall be taken into account. For example, in the case detailed below, for circuit-breaker CB1, the worst condition occurs when the fault is right upstream of the circuit-breaker itself. To determine the breaking capacity of the circuit-breaker, the contribution of two transformers in parallel must be considered. Fault right downstream of CB1 Fault right upstream of CB1 (worst condition for CB1)Once the short-circuit power equivalent at the fault point has been determined, the short-circuit current can be calculated by using the following formula: Three-phase short-circuit Two-phase short-circuit 6.3.3 Calculation of the short-circuit current To determine the short-circuit current in an installation, both the fault point as well as the configuration of the system which maximize the short-circuit current involving the device shall be considered. If appropriate, the contribution of the motors shall be taken into account. For example, in the case detailed below, for circuit-breaker CB1, the worst condition occurs when the fault is right upstream of the circuit-breaker itself. To determine the breaking capacity of the circuit-breaker, the contribution of two transformers in parallel must be considered. Fault right downstream of CB1 Fault right upstream of CB1 (worst condition for CB1) 6.3 Determination of the short-circuit current: “short-circuit power method” 492 Electrical devices | ABB 6 Calculation of short-circuit current SkEL Ik SkUP SkUP = ° SkUP = 1000 MVA SkUP = 750 MVA SkUP = 500 MVA SkUP = 250 MVA SkUP = 100 MVA SkUP = 50 MVA SkUP = 40 MVA SkUP = 30 MVA SkUP = 20 MVA SkUP = 10 MVA SkEL [MVA] Ik [kA] 0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 0 10 20 30 40 50 60 70 80 90 100 1SDC010052F0001 As a first approximation, by using the following graph, it is possible to evaluate the three-phase short-circuit current downstream of an object with short-circuit power (SkEL) known; corresponding to this value, knowing the short-circuit power upstream of the object (SkUP), the value of Ik can be read on the y-axis, expressed in kA, at 400 V. Figure 1: Chart for the calculation of the three-phase short-circuit