The working principle of the relay introduces the role of the relay

In many household appliances, in order to prevent the current from being too large to damage the appliance, some relays are installed on the appliance. Then, let's introduce the electrical principle and precautions of the relay for everyone to refer to in real life.

First, the working principle of the relay :

The working principle of the relay is mainly based on the input characteristics of the integrated circuit driver, driving and backing some currents to improve the stability of the current. The main principle is to use the coil of the relay to energize, the relay contacts to pick up, and the output current It is relatively low-level, which can play a role in protecting electrical appliances. If the current value in the circuit is too large, the coil of the relay will be automatically powered off. When the contact is disconnected, the reverse current can be used, and the relay can be directly driven.

Second, judge the maintenance of the relay good or bad:

In fact, the method of judging good or bad is very simple. You only need to insert the current of the input and output terminals with the multimeter DC file. If the output is 1 to 7 low frequency, the output voltage is 10 to 16 and must be high frequency. Voltage. If the voltage at the input is very normal and the voltage at the output is high, this indicates that the drive is also damaged. You can use other methods to repair and repair it so that the relay can work normally.

Relay knowledge

A relay is an electronic control device that has a control system (also called an input loop) and a controlled system (also called an output loop). It is usually used in an automatic control circuit. It actually uses a small current to control the larger. An "automatic switch" of current. Therefore, it plays the role of automatic adjustment, safety protection and conversion circuit in the circuit.

Several functions of the relay:

1) Expand the scope of control. For example, when the multi-contact relay control signal reaches a certain value, it can switch, disconnect, and turn on multiple circuits at the same time according to different forms of the contact group.

2) Zoom in. For example, sensitive relays, intermediate relays, etc., can control very high power circuits with a very small amount of control.

3) Integrated signal. For example, when a plurality of control signals are input to a multi-winding relay in a prescribed form, the comparison is integrated to achieve a predetermined control effect.

4) Automatic, remote control, monitoring. For example, a relay on an automated device, together with other appliances, can form a program control circuit for automated operation.

Classification of solid state relays

Solid State Relay (SSR) is a kind of contactless electronic switch. It is composed of discrete components, film fixed resistor network and chip. It is assembled by hybrid process to realize the control circuit (input circuit) and load circuit (output circuit). Isolation and signal coupling, the on-off switching function of the load is realized by the solid-state device, and there is no movable part inside. Although the types of solid state relays on the market are numerous, their operation is basically similar. It mainly consists of three parts: input (control) circuit, drive circuit and output (load) circuit.

The input circuit of the solid state relay provides a loop for the input control signal, making it the trigger source for the solid state relay. The input circuit of the solid state relay is mostly DC input, and the individual is the AC input. The DC input circuit is further divided into a resistive input and a constant current input. The input control current of the resistive input circuit varies linearly with the input voltage. The constant current input circuit, when the input voltage reaches a certain value, the current no longer increases significantly with the increase of the voltage. This relay can be applied to a relatively wide input voltage range.

We offer a wide range of relay products, such as: Phoenix solid state relays; OPT-24DC/24DC/2 (2966595), shock and shock resistance, long service life, especially suitable for applications requiring coupling, power control and extended control range.

The driving circuit of the solid state relay may include an isolation coupling circuit, a function circuit and a trigger circuit. Isolation coupling circuit, currently uses two types of circuit forms: optocoupler and high frequency transformer. Commonly used optocouplers are light-triode, light-two-way thyristor, light-diode array (light-volt), and the like. The high-frequency transformer is coupled to form a self-oscillating oscillation of about 10 MHz under a certain input voltage, and the high-frequency signal is transmitted to the transformer secondary through the transformer core. The functional circuit can include various functional circuits such as detection rectification, zero-crossing, acceleration, protection, and display. The function of the trigger circuit is to provide a trigger signal to the output device.

The output circuit of the solid state relay realizes the on/off switching of the solid state relay under the control of the trigger signal. The output circuit is mainly composed of an output device (chip) and an absorption circuit that acts as a transient suppression function, and sometimes includes a feedback circuit. At present, the output devices used in various solid state relays mainly include Transistor, thyristor (Syristor or SCR), Triac, MOS MOSFET, and insulated gate bipolar. Transistor (IGBT), etc.

The relay circuit diagram, as well as the circuit function and working principle of the solid state relay, as well as the method of maintenance, are introduced here.