Complete set of relay types

Relays are mainly used for signal conversion in control and protection circuits. It has an input circuit (also called a sensing element) and an output circuit (also called an actuator). When the input quantity in the sensing element (such as current, voltage, temperature, pressure, etc.) changes to a certain value, the relay will act, and the actuator will turn on and off the control loop. A relay is an electrical appliance that transmits signals and is used to switch on and off the control circuit. The input signal of the relay can be electrical quantities such as voltage and current, or non-electrical quantities such as temperature, speed, light, and oil pressure, while the output is all contact actions.

There are many types of relays. According to the input quantity, they can be divided into voltage relays, current relays, time relays, speed relays, pressure relays, etc.; according to the working principle, they can be divided into electromagnetic relays, induction relays, electric relays, electronic relays, etc.; According to the purpose, it can be divided into control relays, protection relays, etc.; according to the input change form can be divided into with or without relays and measuring relays.

Most of the relays used in the control circuit are electromagnetic relays. Electromagnetic relay has simple structure, low price, convenient use and maintenance, small contact capacity (generally less than 5A), large number of contacts, no main and auxiliary points, no arc extinguishing device, small size, rapid action, accurate, The control is sensitive and reliable, and it is widely used in low-voltage control systems. Commonly used electromagnetic relays include current relays, voltage relays, intermediate relays, and various small general-purpose relays.

The intermediate relay plays the function of logic conversion and state memory in the control circuit, and is used to expand the capacity and number of contacts. In addition, in the control circuit, the action time between the relays and switches can be adjusted to prevent the circuit from malfunctioning. The intermediate relay is essentially a voltage relay, which operates according to the presence or absence of the input voltage. Generally, there are many pairs of contacts, and the rated current of the contact capacity is about 5A to 10A.

The input of the current relay is current, which is a relay that acts according to the magnitude of the input current. The coil of the current relay is serially connected to the circuit to reflect the change of the circuit current. The coil has a small number of turns, a thick wire and a small impedance. Current relays can be divided into undercurrent relays and overcurrent relays.

The input of the voltage relay is the voltage of the circuit, which acts according to the input voltage. Similar to current relays, voltage relays are also divided into undervoltage relays and overvoltage relays.

The time relay is used for time control in the control circuit. There are many types, according to its action principle can be divided into electromagnetic, air damping, electric and electronic, etc.; according to the delay mode can be divided into power-on delay type and power-off delay type.

Thermal relays are mainly used for overload protection of electrical equipment (mainly motors). Thermal relay is an electrical appliance that uses the principle of current thermal effect. It has inverse time action characteristics similar to the allowable overload characteristics of the motor. It is mainly used in conjunction with contactors to protect three-phase asynchronous motors against overload and phase failure.

Donghai Tongling Electrical Appliance Co., Ltd. is a professional electromagnetic relay manufacturer with core products such as T73 relays, T78 relays, and T90 relays. The main products are 12vdc relay, 24vdc relay, relais 12v, 4pin relay, 5 pin relay 24v, etc.