The general circuit is often divided into two parts: the main circuit and the control circuit. The relay is mainly used for the control circuit and the contactor is mainly used for the main circuit; The relay can realize the function of using one control signal to control another or several signals, and complete the control of start, stop and linkage. The main control object is the contactor; The contact of the contactor is relatively large and has strong bearing capacity. It can realize the control from weak current to strong current, and the control object is electrical appliances.

1、擴大控制范圍：例如，多觸點繼電器控制信號達到某一定值時，可以按觸點組的不同形式，同時換接、開斷、接通多路電路。

1. Expand the control range: for example, when the control signal of multi contact relay reaches a certain value, it can change, disconnect and connect multiple circuits at the same time according to different forms of contact groups.

2、放大：例如，靈敏型繼電器、中間繼電器等，用一個很微小的控制量，可以控制很大功率的電路。

2. Amplification: for example, sensitive relay, intermediate relay, etc. with a very small control quantity, a circuit with large power can be controlled.

3、綜合信號：例如，當(dāng)多個控制信號按規(guī)定的形式輸入多繞組繼電器時，經(jīng)過比較綜合，達到預(yù)定的控制效果。

3. Integrated signal: for example, when multiple control signals are input into multi winding relay in the specified form, the predetermined control effect can be achieved through comparison and integration.

4、自動、遙控、監(jiān)測：例如，自動裝置上的繼電器與其他電器一起，可以組成程序控制線路，從而實現(xiàn)自動化運行

4. Automatic, remote control and monitoring: for example, the relay on the automatic device and other electrical appliances can form a program control circuit to realize automatic operation

不同的繼電器接線方法會有些差異。下面介紹的是8個接線端子的接線方法。

Different relay wiring methods will be different. The following describes the wiring method of 8 terminals.

5和6是一對公共端子，1和2是一對常閉觸點，3和4是一對常開觸點。7、8不通電時，5—6和1—2接通，通電后就會斷開1—2，而5—6不斷，再和3—4接通.

5 and 6 are a pair of common terminals, 1 and 2 are a pair of normally closed contacts, and 3 and 4 are a pair of normally open contacts. 7. 8 when power is off, 5-6 and 1-2 are connected. After power is on, 1-2 will be disconnected, and 5-6 will continue to be connected with 3-4

一般中間繼電器是雙刀雙擲開關(guān)，7—8端子接內(nèi)部的線圈，使用時會并聯(lián)一個續(xù)流二極管，二極管接入時的極性和繼電器端子標注相反（8+接二級管的負極，7-接二級管的正極），達到預(yù)定值時，繼電器會工作驅(qū)動電路斷開，那一瞬間會因為自感電壓產(chǎn)生很高的的電流，而這個電流會流過續(xù)流二級管，而不會經(jīng)過起到電路，從而保護了電路中的元件。

Generally, the intermediate relay is a double pole double throw switch. Terminals 7-8 are connected to the internal coil. When in use, a freewheeling diode will be connected in parallel. The polarity when the diode is connected is opposite to that marked on the relay terminal (8 + is connected to the negative pole of the secondary tube and 7-is connected to the positive pole of the secondary tube). When the predetermined value is reached, the relay will work and the driving circuit will be disconnected, At that moment, a high current will be generated due to the self induced voltage, and this current will flow through the freewheeling diode without passing through the starting circuit, so as to protect the components in the circuit.