1. 概述

Overview

在工业应用中，剩余电流继电器与外部剩余电流互感器结合使用以检测和评估接地故障电流。它们也可以与保护装置结合使用，以实现电路的断开，从而实现对线路和人员的保护。

Residual current relay can be combined with external residual current transformer to detect and evaluate the ground fault current. They can also be combined with protective devices to realize the disconnection of circuits and the protection of lines and workers.

2.剩余电流的定义以及危害

Definition and risk of residual current

剩余电流，是指低压配电线路中各相(含中性线)电流矢量和不为零的电流。通俗讲当用电侧发生了事故,电流从带电体通过人体流到大地,使主电路进出线中的电流I相和I中的大小不相等,此时电流的瞬时矢量合成有效值称为剩余电流，俗称漏电。

Residual current is the current vector sum of each phase (including the neutral ) in the low-voltage distribution that not be zero. Generally, when there is an accident on the power side, the current flows from the charged body to the earth through the human body,it will cause that the current phase I in the main circuit not equal to the size in phase I. At this time, the value of instantaneous current vector synthesis is called residual current, commonly known as leakage.

TN System

3.剩余电流的危害：

Risk of residual current:

人身触电。当电气设备因绝缘损坏而使外壳带电，而工作人员又接触此外壳时，就会导致人身触电事故。

（1）Physical electric shock. When shell of the electrical equipment is electrified due to insulation damage, and the workers touch the shell again, it will lead to physical electric shock accident.

烧损电气设备，引起火灾。长期存在的漏电电流，尤其是两相经过电阻接地的漏电电流，在通过设备绝缘损坏处时将散发出大量的热，使绝缘进一步损坏，甚至使可燃性材料（如非阻燃性橡套电缆）着火燃烧。

Burn electrical equipment and cause fire. The long-term leakage current, especially the leakage current of  two-phase grounded through resistance, will release a lot of heat when flow through the damaged part of the equipment insulation, further damaging the insulation, and even making combustible materials (such as non flame retardant rubber sheathed cable) burn on fire.

引起短路事故。据统计，约有30%的单相接地故障发展为短路。从而造成更大的电气故障。长期存在的漏电电流及电火花使漏电处的绝缘进一步损坏，后危及相间绝缘而造成短路。

(3) Cause short circuit accident. According to statistics, about 30% of single-phase grounded faults develop into short circuit which will give rise to heavier electrical failure. The long-term leakage current and spark further damage the insulation at the leakage point, and finally endanger the interphase insulation and cause short circuit.

引起电气火灾事故。电网发生单相接地或设备发生单相碰壳时，在接地点就会产生电火花，若此电火花具有足够的能量，就可能点燃易燃易爆物品。

Cause electrical fire accident. When the single-phase grounding occurs in the power grid or the single-phase collision occurs in the equipment, the electric spark will be generated at the grounding point. If the electric spark has enough energy, it may ignite flammable and explosive materials.

4.如何测剩余电流

How to measure residual current

在被测的三相导线路上与N线上各装一个CT，或让三相导线与N线一起穿过一个零序CT，得到三相导线与中性线N的电流矢量和IA*+IB*+IC*+IN*，当没有发生单相接地故障时，无论三相负荷平衡与否，则此矢量和为零；当发生某一相接地故障时，故障电流中会通过保护PE及与地相关连的金属构件回到电源，即IA*+IB*+IC*+IN*，此时数值为接地故障电流Id。

Installing a CT on each of the three-phase conducting lines to be tested and N line or let the three-phase conductor and the n-line pass through a zero sequence CT together to get the current vector sum IA * + IB * + IC * + IN * . when there is no single-phase grounded fault, whether the three-phase load is balanced or not, the vector sum is zero; when there is a phase grounded fault, the fault current will flow through the protection PE and the metal components connected to the earth to the power supply, at this time, the value is the ground fault current Id.

5.ASJ系列剩余电流动作继电器

ASJ series residual current operated relay

ASJ系列剩余电流动作继电器可与低压断路器或低压接触器等组成组合式剩余电流保护装置， 主要适用于交流 50Hz， 额定电压 400V 及以下的 TT 和 TN 系统配电线路， 用来对电气线路进行接地故障保护， 防止接地故障电流引起的设备损坏和电气火灾事故， 也可用来对人身触电危险提供间接接触保护。

ASJ series residual current action relay can be combined with low voltage circuit breaker or low voltage contactor to form a combined residual current protection device.It is mainly used for TT and TN system distribution lines with AC 50Hz and rated voltage of 400V and below.It is used to protect the electrical circuit from ground faults, prevent equipment damage caused by ground fault current and electrical fire accidents, and can also be used to provide indirect contact protection against personal electric shock hazard

参考文献 Bibliography

1.Solutions For Enterprise Micro-grid System 2020.02

安科瑞 缪阳扬

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