What Are the Best Tips for Relay Wiring?

Time relay refers to a type of relay whose output circuit needs to pass a specified accurate time after the input action signal is added (or removed). It is an electrical component used in a circuit with a lower voltage or a lower current to switch on or off a circuit with a higher voltage or a higher current.

Time relay is a very important component in electrical control systems.

I. Classification by working principle

According to different working principles, time relays can be divided into air damped time relays, electric time relays, electromagnetic time relays, electronic time relays and so on.

(1) The air-damped time relay uses the principle of damping when air passes through a small hole to obtain a delay. Its structure is composed of an electromagnetic system, a delay mechanism and contacts. The electromagnetic mechanism is a double-port direct-acting type, the contact system is a micro-switch, and the time-delay mechanism uses an airbag type damper.

(2) Electronic time relay

Electronic time relay is used

The electrical control system of the time relay is a very important component. Generally divided into two types of power-on delay and power-off delay. There are electronic and mechanical types from the principle of operation. The electronic method adopts the principle of capacitor charging and discharging and then cooperates with electronic components to realize the delay action. There are many types of mechanical types, and there are airbag types using airbags and springs.

Wiring method of time relay:

1. Control wiring: Think of it as a DC relay;

2. Work control: Although the control voltage is connected, whether it plays a controlling role is determined by the timer on the panel;

3. Functional understanding: It is a switch, single-pole double-throw, with a movable point movable arm, just like the movable knife arm of a common knife switch;

4: Load wiring: the neutral or negative terminal of the power supply is connected to the neutral or negative terminal of the appliance;

5. Working principle: The time period is invalid, which is equivalent to the off state of the normal light switch. When it is effective, the relay is activated, and the electric appliance is powered to work, which is equivalent to the normal ON state of a light switch.

Technical parameters include rated voltage, contact working current, contact type and number, delay range, accuracy, adaptability to ambient temperature, mechanical life and electrical life, etc. Taking SJ23 series air time relay as an example, its technical parameters are as follows:

1) Rated control capacity: AC300VA, DC60W (delay head assembly 30W).

2) The rated voltage level of the relay: AC380V, 220V, DC220V, 110V.

3) The rated voltage of the coil: AC110V, 220V and 380V.

4) The maximum working current of the contact: 0.79A at AC380V, 0.27A (momentary) and 0.14A (delay) at DC220V.

5) Delay repeat error: 9%.

6) Hot-state pull-in voltage: not more than 85% of the rated voltage of the relay. When the voltage in the cold state drops from the rated value to 10% of the rated value, it can be reliably released, and it can also be reliably released after 110% of the rated voltage.

7) The mechanical life is not less than 1 million times, and the electrical life is 1 million times (the DC life of the delay head component is 500,000 times). ^[3]

The selection of time relay is mainly a matter of delay mode and parameter coordination. The following aspects should be considered when selecting.

(1) Selection of delay mode. There are two types of time relays: power-on delay or power-off delay. They should be selected according to the requirements of the control circuit. The reset time after the action is longer than the inherent action time, so as to avoid misoperation or even delay, which is especially important in the case of repeated delay circuits and frequent operations.

(2) Type selection. Where low delay accuracy is required, generally low-cost electromagnetic or air-damped time relays are used. Conversely, when high delay accuracy is required, electronic time relays can be used.

(3) Coil voltage selection. According to the voltage of the control circuit, ask the voltage of the relay attraction coil.

(4) Selection of power parameter changes. When the power supply voltage fluctuates, it is better to use air damping or electric time relay than the transistor type, and when the power supply frequency fluctuates, it is not suitable to use electric time relay, and where the temperature changes greatly, it is not suitable to use air Damped time relay. ^[4]

1) Keep the time relay clean, otherwise the error will increase.

2) Check whether the voltage and frequency of the power supply match the voltage and frequency of the time relay before use.

3) Select the length of the control time of the time relay according to user requirements.

4) DC products should pay attention to wiring according to the circuit diagram, pay attention to the polarity of the power supply.

5) Try to avoid using in places with obvious vibration, direct sunlight, humidity and oil. ^[5]