1. When selecting contactors, we should start from the working environment and mainly consider the following factors

①控制交流负载应选用交流接触器，直流负载选用直流接触器

① AC contactor shall be selected for controlling AC load and DC contactor shall be selected for DC load

②主触头的额定工作电流应大于等于负载电路的电流，还要注意的是接触器主触头的额定工作电流是在规定的条件下（额定工作电压、使用类别、操作频率等）能够正常工作的电流值，当实际使用条件不同时，这个电流值也将随之改变。

② The rated working current of the main contact shall be greater than or equal to the current of the load circuit. It should also be noted that the rated working current of the main contact of the contactor is the current value that can work normally under the specified conditions (rated working voltage, use category, operation frequency, etc.). When the actual use conditions are different, this current value will also change.

③主触头的额定工作电压应大于等于负载电路的电压。

③ The rated working voltage of the main contact shall be greater than or equal to the voltage of the load circuit.

④线圈的额定电压应与控制回路电压一致

④ The rated voltage of the coil shall be consistent with the voltage of the control circuit

接触器选择的具体步骤

Specific steps for contactor selection

①选择接触器的类型，需要根据负载种类选择接触器的类型

① To select the type of contactor, you need to select the type of contactor according to the load type

负载种类：一类、二类、三类、四类

Load type: class I, class II, class III and class IV

标记名：AC-1、AC-2、AC-3、

Tagnames: ac-1, AC-2, AC-3

控制对象：无感或徵感负载、异步电动机的启动和停止、笼型异步电动机的运转和运行、笼型异步电动机的启动、反接制动、反转和点动，

Control objects: non inductive or characteristic load, start and stop of asynchronous motor, operation and operation of cage asynchronous motor, start, reverse braking, reverse rotation and inching of cage asynchronous motor,

②选择接触器的额定参数

② Select the rated parameters of the contactor

根据被控对象和工作参数，如电压、电流、功率、频率等，确定接触器的额定参数。

Determine the rated parameters of the contactor according to the controlled object and working parameters, such as voltage, current, power, frequency, etc.\

（1）接触器的线圈电压，一般应低一些为好，这样对接触器的绝缘要求可以降低，使用时也比较。当控制电路简单，使用电器比较少时，可直接选用380V或220V的电压。若电路复杂。使用电器的个数超过5个时，可选用36V或110V电压的线圈，以保证。但为了方便和减少设备，常按实际电网电压选取。

(1) The coil voltage of the contactor should generally be lower, so that the insulation requirements of the contactor can be reduced and it is safer to use. When the control circuit is simple and few electrical appliances are used, 380V or 220V voltage can be directly selected. If the circuit is complex. When the number of electrical appliances exceeds 5, 36V or 110V coils can be selected to ensure safety. However, in order to facilitate and reduce equipment, it is often selected according to the actual grid voltage.

（2）电动机的操作频率不高，如压缩机、水泵、风机、空调等，接触器额定电流大于负载额定电流即可。

(2) The operating frequency of the motor is not high, such as compressor, water pump, fan, air conditioner, etc. the rated current of the contactor is greater than the rated current of the load.

（3）对重任务型电动机，如机床主电动机、升降设备等，选用时接触器额定电流大于电动机的额定电流

(3) For heavy duty motors, such as machine tool main motors and lifting equipment, when selected, the rated current of the contactor is greater than the rated current of the motor

（4）对特种用途电动机。经常运行于启动反转的状态时，接触器大致可按电寿命及启动电流选用，可选CJ10Z、CJ12、

(4) For special purpose motors. When it often operates in the state of start reversal, the contactor can be selected according to the electrical life and starting current, and cj10z, cj12

（5）用接触器对变压器进行控制时，应考虑浪涌电流的大小。例如电焊机，一般可按变压器额定电流的2倍选取接触器，如CJT1、CJ20等。

(5) When controlling the transformer with contactor, the magnitude of surge current shall be considered. For example, for electric welding machines, contactors can generally be selected according to twice the rated current of the transformer, such as cjt1, cj20, etc.

（6）接触器的额定电流是指接触器在长期工作下的允许电流，持续时间≤8H，且安装于敞开的控制板上，如果冷却条件较差，选用接触器时，接触器的额定电流按负载额定电流的1.1-1.2倍选取。

(6) The rated current of the contactor refers to the maximum allowable current of the contactor under long-term operation, with duration ≤ 8h, and installed on the open control board. If the cooling conditions are poor, when selecting the contactor, the rated current of the contactor shall be selected according to 1.1-1.2 times of the rated current of the load.

（7）选择接触器的数量和种类。触头的数量和种类应满足控制电路的要求。

(7) Select the number and type of contactors. The number and type of contacts shall meet the requirements of control circuit.