Two basic functions of intermediate relay in practical application:

1、中间继电器触点扩展，一般用在主回路居多：

1. The contact extension of intermediate relay is generally used in the main circuit:

例如：中间继电器用在主回路中，和交流接触器并联，用来扩展交流接触器的触点，弥补触点使用情况不足的缺点。

For example, the intermediate relay is used in the main circuit in parallel with the AC contactor to expand the contact of the AC contactor and make up for the shortage of contact use.

2、进行电气隔离一般多应用于控制电路中：

2. Electrical isolation is generally used in control circuits:

就是我们平常使用的原理：小电流来控制大电流，小电压来控制大电压，对于主回路中大电流和大电压进行隔离。

It is the principle we usually use: small current to control large current, small voltage to control large voltage, and isolate large current and large voltage in the main circuit.

中间继电器实物运用：如何用微型继电器控制负载，图中我们用继电器控制一盏灯，13---14接入电源，零线直接进灯，火线进继电器常开点9，经过常开点出来就是5，接到灯上面，当继电器通电的时候常开触点闭合，灯得电亮起来。

Physical application of intermediate relay: how to use micro relay to control the load. In the figure, we use relay to control a lamp. 13-14 are connected to the power supply, the zero line directly enters the lamp, the live line enters the relay normally open point 9, and comes out through the normally open point is 5. It is connected to the lamp. When the relay is powered on, the normally open contact is closed and the lamp is powered on.

继电器常开---常闭运用=13---14接继电器电源，零线分别进两个灯，火线进继电器公共端9，然后5出来进灯，1号端子出来进灯，微型继电器初始状态1号端子上面的灯会亮起来，因为1---9是常闭点，继电器得电吸合5号接线端子灯会亮起来。因为继电器得电，常开触点闭合，所以灯会亮起来。

Relay normally open --- normally closed application = 13 --- 14 connect the relay power supply, the zero line enters two lamps respectively, the live line enters the relay common terminal 9, then 5 comes out and enters the lamp, and terminal 1 comes out and enters the lamp. In the initial state of the micro relay, the lamp on terminal 1 will light up, because 1 --- 9 is the normally closed point, the relay is powered on and pulled in, and the lamp on terminal 5 will light up. Because the relay is energized and the normally open contact is closed, the light will come on.

中间继电器实际运用图2.jpg

Actual application of intermediate relay Fig. 2.jpg

光电开关控制微型继电器：我们用继电器控制报警器，合上电源报警器就响起来，所以我们用光电开关控制继电器，既然控制继电器我们就要控制继电器的线圈，如图中所示，当我们触碰到光电开关，继电器得电，报警器才会响。

Photoelectric switch controls micro relay: first, we use the relay to control the alarm. When the power supply is turned on, the alarm will sound, so we use the photoelectric switch to control the relay. Since we control the relay, we need to control the coil of the relay, as shown in the figure. When we touch the photoelectric switch, the relay will power on and the alarm will sound.

光电开关220V加中间继电器报警工作原理：我们图中所用的电器元件都是220V，所以电源接零线，火线分别进到继电器的常开触点上面，触点进报警器的电源。光电开关接线，零线进光电开关。

Working principle of photoelectric switch 220V plus intermediate relay alarm: firstly, the electrical components used in our drawing are 220V, so the power supply is connected to the zero line, the live line is respectively connected to the normally open contact of the relay, and the contact is connected to the power supply of the alarm. Photoelectric switch wiring, zero line into photoelectric switch.

经过光电开关常开进继电器线圈13，火线进继电器的线圈14，当我们触碰到光电开关的时候，光电开关常开点闭合，这时候继电器线圈得电，常开触点闭合，报警器得电响起来，当我们离开 光电开关，常开点断开，继电器失电，报警器失电停止响声。这就是光电开关如何控制继电器。以及继电器如何用到实际电路中，起到传递信号的作用。

When we touch the photoelectric switch, the normally open point of the photoelectric switch is closed. At this time, the relay coil is powered on, the normally open contact is closed, and the alarm is powered on and sounds. When we leave the photoelectric switch, the normally open point is disconnected, the relay is powered off, and the alarm stops sounding. This is how the photoelectric switch controls the relay. And how the relay is used in the actual circuit to transmit signals.