漏电保护器电路原理图

Leakage protector circuit schematic introduction

In the figure, L is an electromagnet coil, which can drive the knife switch K1 to be disconnected during leakage, and each bridge arm can increase the withstand voltage by connecting two 1N4007 series. R3 and R4 have large resistance values. Therefore, when K1 is closed, the current flowing through L is small enough to cause K1 to be disconnected. R3 and R4 are voltage equalizing resistors of the thyristors T1 and T2, which can reduce the withstand voltage requirement of the thyristor. K2 is a test button that functions as a simulated leakage. Pressing the test button K2, K2 is turned on, which is equivalent to leakage of the external line to the ground, so that the vector sum of the currents of the three-phase power line and the neutral line passing through the magnetic ring is not zero, and the detection coil on the magnetic ring a, There is an induced voltage output at both ends of b, and this voltage immediately triggers T2 conduction. Since C2 has a certain voltage in advance, after T2 is turned on, C2 is discharged through R6, R5, and T2, so that a voltage is generated on R5 to trigger T1 to conduct. After T1 and T2 are turned on, the current flowing through L increases, the electromagnet operates, and the drive switch K1 is turned off. The function of the test button is to check whether the function of the device is intact at any time. The principle of the electromagnet leakage caused by the leakage of the electric equipment is the same. R1 is a varistor that acts as an overvoltage protection.

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Diagram of working principle of leakage protector

Figure 1 shows the working principle of the leakage protector. In normal operation, no leakage current flows through the leakage protector except the working current. At this time, the current flowing through the zero-sequence transformer (detecting the transformer) is equal, the direction is opposite, and the sum is zero. The induced magnetic flux in the transformer core is also equal to zero, the secondary winding has no output, the automatic switch remains in the on state, and the leakage protector is in normal operation. When the protected electrical equipment and the line are leaking or someone is getting electric shock, there is a ground fault current, so that the current flowing through the detecting transformer is not zero, the magnetic flux is induced in the transformer core, and the secondary winding has induction. The current is generated and output after being amplified, so that the operation of the leakage release device pushes the automatic switch to trip to achieve the purpose of leakage protection.

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xx虽然漏电保护器的工作原理相对简单,但在实际使用中会出现这样的错误,造成不必要的误操作或拒绝。以下是售后服务中遇到的一些常见示例。

图2是安装人员接线错误,插座的中性点N端错误连接到保护接地(PE)端子,如图2中b所示,当使用插座时,电流通过零线。保护地线返回电源,使漏电保护器工作。校正方法如图2所示。

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图3误用了三相三线漏电保护器。由于中性线不通过漏电保护器,漏电保护器不检测漏电流而是检测三相不平衡电流,因此在三相线中只连接一相。在任何负载下,电流都会远远超过漏电流,校正方法是用三相四线漏电开关更换漏电保护器。

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线路不能同时供电,因为两个负载的大小不同。

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图5:安装漏电保护器时,不能重复接地。否则,通过零序变压器的电流减小,导致漏电保护跳闸而不会跳闸。

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图6:零保护线检测变压器。当设备泄漏时,相线漏电流通过零保护线并返回检测变压器,使变压器不检测漏电流,导致漏电保护器不工作。

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稍后指出的漏电保护器的安装位置不应太高。 “测试按钮”应处于易于操作的位置。测试按钮的目的是模拟人为泄漏,强行绊倒泄漏保护,验证它是否能正常工作,至少每月测试一次。一旦。如果失败或不起作用,应立即将其移除以进行维修或更换。按下按钮的时间不得超过IS,不能连续连续操作,以免烧坏测试电阻扣线圈。

哪种电气设备需要安装漏电保护器?

《施工现场临时用电安全技术规范》规定“除了保护和零连接外,施工现场的所有电气设备必须安装在设备负载线的头端。”以上规定涉及三个方面:

1施工现场的所有电气设备应配备漏电保护器。由于建筑物的开放性,潮湿的环境,不断变化的人员以及设备的薄弱管理,用电的危险性很高,需要所有的电力设备,包括电力和照明设备,移动和固定设备。当然,不包括由安全电压源和隔离变压器供电的设备。

2根据规定,原始保护零(接地)措施仍未按要求保持不变。这是安全使用电力的最基本技术措施,不能拆除。

3漏电保护器安装在电气设备负载线的头端。这样做的目的是保护负载线,同时保护电气设备,防止线路绝缘损坏引起的触电事故。