What are the types of relays? What does it do? Relay is according to some input signal to turn on or off the small current control circuit, to achieve remote control and protection of automatic control appliances. At present, the relay input can be current, voltage and other electric quantity, but also can be temperature, time, speed, pressure and other non-electric quantity, and the output is the action of the contact or the change of circuit parameters. When the input voltage, current and frequency of the relay or temperature, pressure and speed and other non-electric quantity reaches the specified value, the contact of the relay will turn on or off the controlled or protected circuit. Relay is generally composed of two parts: input sensing mechanism and output actuator. The former is used to reflect the level of input, and the latter is used to turn on or cut off the circuit. The commonly used relay is a contact, the contact has two states of on and off, and the change of the state is driven by a certain mechanism. The action of the contact of the voltage relay and the action voltage of the coil is related to the voltage relay, which is used for voltage protection and control of the electric drive system. When the coil of the voltage relay is used, it is parallel with the load. Features: the number of turns of the coil is large and the wire diameter is small. Classification: According to the type of coil current can be divided into AC and DC voltage relay, according to the size of the pull-in voltage can be divided into over voltage, under voltage and zero voltage relay. The function of the intermediate relay of the interconnector is to increase the number of controlled lines or increase the allowed disconnection capacity of the contact to achieve the purpose of distributing control signals and power amplification. There are two kinds of intermediate relays: AC and DC. Intermediate relays are characterized by a large number of contacts, generally more than 3~4 pairs, and the contact form is often bridge-shaped contacts (the same as the contacter auxiliary contacts). The intermediate relay with larger action power has the same structure as the small contactor. It is suitable for the control line below 500V AC. The coil voltage is 12V, 36V, 127V, 220V and 380V AC. The relay has eight pairs of contacts with a current rating of 5A and a maximum operating frequency of 1200 cycles /H.