一、接触器的功能：

接触器是全自动的控制电器。接触器不能够切断短路电流，它可以频繁地接通或分断交、直流电路，并可实现远距离控制。其主要控制对象是交、直流电动机，也广泛用于控制其它电力负载，如电焊机、电容器、电热设备、照明组等。它具有低电压释放保护功能，还具有控制容量大、过载能力强、寿命长、结构简单、价格便宜等特点，在电力拖动、自动控制线路中得到广泛的应用。

二、接触器的构造

接触器是一种电磁式自动开关。 接触器是靠电磁力操作的，按操作电源不同可分为直流和交流两大类。两类结构大致相同。（以下都以交流接触器为例）

接触器的结构：由电磁系统、触点系统、灭弧装置、反力装置、支架和底座等几部分组成：

1、电磁系统 电磁机构的组成：由电磁线圈、铁心和衔铁组成。 电磁机构的功能：操作触点的闭合和断开。

2、触点系统触点是接触器的执行元件，用来接通或断开被控制电路。触点系统包括主触点和辅助触点。

（1） 主触点：用在通断电流较大的主电路中。

（2）辅助触点：用于接通或断开控制电路，只能通过较小的电流。按其原始状态可分为常开触点和常闭触点。触点系统包括主触点和辅助触点。

◆常开触点：原始状态时（即线圈未通电）断开，线圈通电后闭合的触点叫常开触点。

◆常闭触点：原始状态闭合，线图通电后断开的触点叫常闭触点（线圈断电后所有触点复原）。

3、灭弧系统：用于分断较大电流时在动、静触点之间产生的电弧，保护触点。容量在10A以上的接触器都有灭弧装置，常采用纵缝灭弧罩及栅片灭弧装置。

4、反力装置包括弹簧、传动机构、接线柱及外壳等。

5、支架和底座用于接触器的固定和安装。

HV-75AP4

First, the function of contactor:

Contactors are fully automatic control appliances. Contactor can not cut short circuit current, it can frequently switch on or break AC, DC circuit, and can achieve remote control. Its main control object is AC, DC motor, but also widely used to control other electric loads, such as welding machines, capacitors, electric heating equipment, lighting groups, etc. It has the function of low voltage release protection, but also has the characteristics of large control capacity, strong overload capacity, long life, simple structure, cheap price, etc., and has been widely used in electric drive and automatic control lines.

Second, the contactor structure

Contactor is an electromagnetic automatic switch. The contactor is operated by electromagnetic force, which can be divided into DC and AC two categories according to the different operating power supply. The two types of structures are roughly the same. (The following are AC contactors as an example)

The structure of the contactor: composed of electromagnetic system, contact system, arc extinguishing device, reaction device, bracket and base, etc.

1, the composition of the electromagnetic system electromagnetic mechanism: composed of electromagnetic coil, iron core and armature. The function of the electromagnetic mechanism: the closing and breaking of the operation contact.

2, contact system contact is the actuator of the contactor, used to connect or disconnect the controlled circuit. The contact system includes main contact and auxiliary contact.

(1) Main contact: used in the main circuit with large on-off current.

(2) Auxiliary contact: used to turn on or off the control circuit, only through a small current. According to its original state, it can be divided into normally open contacts and normally closed contacts. The contact system includes main contact and auxiliary contact.

◆ Normally open contact: the original state (that is, the coil is not powered on) is disconnected, and the contact that is closed after the coil is powered on is called normally open contact.

◆ Normally closed contact: the original state is closed, and the contact that is broken after the line is powered on is called normally closed contact (all contacts are restored after the coil is powered off).

3, arc extinguishing system: used to break the arc generated between the dynamic and static contacts when the current is large, to protect the contacts. Contactors with a capacity of more than 10A have arc extinguishing devices, often using longitudinal slit arc extinguishing covers and grid plate arc extinguishing devices.

4, the reaction device includes spring, transmission mechanism, terminal and shell, etc.

5, bracket and base for contactor fixing and installation.