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零序电流互感器的原理 Principle of zero sequence current transformer 　　零序电流互感器保护的基本原理是基于基尔霍夫电流定律: 流入电路中任一节点 的复电流的代数和等于零,即 ∑I=0,它是用零序 CT 作为取样元件.在线路与 电气设备正常的情况下,各相电流的矢量和等于零(对零序电流保护假定不考虑 不平衡电流),因此,零序 CT 的二次侧绕组无信号输出(零序电流保护时躲过 不平衡电流) 执行元件不动作. , 当发生接地故障时的各相电流的矢量和不为零, 故障电流使零序 C.T 的环形铁芯中产生磁通, 零序 C.T 的二次侧感应电压使执行 元件动作,带动脱扣装置,切换供电网络,达到接地故障保护的目的. Is the basic principle of zero sequence current transformer protection based on kirchhoff's current law: into any node in the circuit of the algebra and zero current, namely the ∑ I = 0, it is zero sequence CT was used as sampling element. In line with the normal operation of electrical equipment, the vector of each phase current and zero (for zero sequence current protection assume that regardless of the unbalance current), as a result, the zero sequence CT secondary winding no signal output (zero sequence current protection from unbalance current) actuators is not action., when the ground fault occurs, non zero vector of each phase current and fault current to zero sequence C.T toroidal core of magnetic flux, the secondary side of the zero sequence C.T executive components induced voltage causes a movement, drive the tripping device, switching power supply network, achieve the goal of earth fault protection. 　　零序电流和剩余电流是不一样的.零序电流测的是 Ia+Ib+Ic,在对称负荷 的时候,它等于 0;但是现实情况中,不可能等于 0,总会有一个不平衡电流.而剩 余电流测量的是 Ia +Ib+Ic+N,这个时候,不管负荷的情况,正常情况是等于 0 的. 所以剩余电流会比零序电流更加灵敏低压漏电零序电流互感器的工作原理如 果在三相四线中接入一个电流互感器,这时感应电流为零.当电路中发生触电或 漏电故障时, 回路中有漏电电流流过, 这时穿过互感器的三相电流相量和不等零, 其相量和为:Ia+Ib+Ic=I(漏电电流)这样互感器二次线圈中就有一个感应电压, 此电压加于检测部分的电子放大电路,与保护区装置预定动作电流值相比较,如 大于动作电流,即使灵敏继电器动作,作用于执行元件掉闸.这里所接的互感器 称为零序电流互感器, 三相电流的相量和不等于零, 所产生的电流即为零序电流. The zero sequence current is different from the residual current. The zero sequence current measures Ia + Ib + Ic, which is 0 when it is symmetric. But in reality, can't be equal to zero, there will always be a unbalance current. The remaining residual current measurement is Ia + Ib + Ic + N, this time, regardless of the load cases, normal is equal to zero. So the residual current will be more sensitive than zero sequence current low-voltage leakage working principle of zero sequence current transformer, such as Fruit in three phase four wire connected to a current transformer, the induced current is zero. When an electric shock or leakage faults in the circuit, leakage current through the loop, then through the transformer of three phase current phasor and range from zero, the phasor and as: Ia + Ib + Ic = I () leakage current in the transformer secondary coil is an induced voltage, the voltage on the detection part electronic amplifier circuit, compared with the scheduled reserve device current value, such as greater than the current action, even sensitive relay operation, apply to components of tripping. Here after the transformer Known as the zero sequence current transformer, three phase current phasor and is not equal to zero, produced by the current is zero sequence current.