1、 Self locking

电动机起动后，松开启动按钮，接触器通过自身常开辅助触头而使线圈保持得电的作用称为自锁。举个简单的例子，想让电动机长时间转，不用一直按着启动按钮，在不按停止按钮和电动机不过载的情况下，只需要点击一下启动按钮，电动机就会一直转。这就是自锁控制电路使电动机连续运转的功能，除此之外自锁控制电路还具有欠压和失压(或零压)保护功能。如下图所示，当按下启动按钮SB2时，接触器KM1得电吸合，使电动机运转，同时接触器常开触点也闭合，即使是松开了SB2，电动机也会继续运转，按下停止按钮SB1时，电动机停止。

After the motor starts, release the start button, and the contactor keeps the coil energized through its normally open auxiliary contact, which is called self-locking. For a simple example, if you want the motor to run for a long time, you don't have to press the start button all the time. If you don't press the stop button and the motor is not overloaded, you just need to click the start button, and the motor will run all the time. This is the function of the self-locking control circuit to make the motor run continuously. In addition, the self-locking control circuit also has the function of under voltage and loss of voltage (or zero voltage) protection. As shown in the figure below, when the start button SB2 is pressed, the contactor KM1 is powered on to make the motor run. At the same time, the normally open contact of the contactor is closed. Even if SB2 is released, the motor will continue to run. When the stop button SB1 is pressed, the motor stops.

二、互锁

2、 Interlock

互锁两个接触器通过自身的常闭辅助触头，相互使对方不能同时得电的作用称为互锁。

Interlocking two contactors through its normally closed auxiliary contact, mutual make each other can not simultaneously power is called interlocking.

1、电气互锁是为了保证电气设备的安 全运行设置的，举个简单的例子，当电动机在正转的时候，如果误操作会使控制正转和反转的接触器同时吸合，这样就会造成短路，如果加入了互锁电路，当电动机正转的时候，就算是按下了控制反转的按钮。

1. Electrical interlock is set to ensure the safe operation of electrical equipment. For a simple example, when the motor is in forward rotation, if the wrong operation will make the contactor controlling forward rotation and reverse rotation pull in at the same time, this will cause a short circuit. If the interlock circuit is added, when the motor is in forward rotation, even if the reverse control button is pressed.

如果正转接触器没有释放到位，也不会让电动机反转。此时，按下按钮SB3控制电动机反转的接触器KM2是不会吸合的。当KM2得电吸合时同理。当按下停止按钮SB1或者是热继电器FR过载时，电动机停止转动。（在互锁电路中我们也看到了自锁）

If the forward contactor is not released in place, it will not reverse the motor. At this time, press the button Sb3 to control the motor reversing contactor km2 will not close. The same is true when km2 is powered on. When the stop button SB1 is pressed or the thermal relay FR is overloaded, the motor stops（ We also see self-locking in interlocking circuit

2、机械互锁电气互锁是当一个接触器打开的同时断开了另一个接触器的线圈电源达到互锁的目的。一般电气互锁是使用接触器辅助触点达到互锁目的，当一个接触器接通的同时，切断另一个接触器的线圈供电回路。

2. Mechanical interlock and electrical interlock is to turn off the coil power supply of another contactor when one contactor is opened to achieve the purpose of interlock. General electrical interlock is to use contactor auxiliary contact to achieve the purpose of interlock. When one contactor is connected, the coil power supply circuit of another contactor is cut off.

机械互锁就是通过机械部件实现互锁，比如两个接触器不能同时合上，可以通过机械杠杆，使得一个接触器合上时，另一个接触器被机械卡住无法合上。

Mechanical interlock is realized by mechanical parts, such as two contactors can not be closed at the same time, through the mechanical lever, so that when one contactor is closed, the other contactor is mechanically stuck and cannot be closed.

电气互锁比较容易实现、灵活简单，互锁的两个装置可在不同位置安装。机械互锁可靠性更高，不用担心误操作，但比较复杂，有时甚至无法实现。通常互锁的两个装置要在近邻位置安装。

The electrical interlock is easy to realize, flexible and simple, and the two interlocking devices can be installed in different positions. Mechanical interlock is more reliable, and there is no need to worry about misoperation, but it is more complex and sometimes can not be realized. Usually, the two interlocking devices should be installed in close proximity.