How much do you know the basics of relays?

Dec. 05, 2019

Speaking of relays, it may not be clear to non-professionals about its specific functions, but in fact it can be seen everywhere in our lives and its application is quite extensive.

Automotive Relay is an electronic component commonly used in automatic control systems for switching circuits on and off. In daily life, you insert the car key, the car can start normally; press the horn, the car can whistle normally; return home, press the remote control, the air conditioner can send a slight breeze . These are all due to different electronics Precision control of relays in the device.

But in the daily use process, the relay also faces a lot of problems: the given current is too large to burn the coil, the relay is too small to work stably; the contact switching voltage and current must also be kept within the normal range, otherwise the relay is easily damaged At the same time, with the gradual popularization of the Internet of Things channels and 5G communication technology, people have higher and more stable requirements for signal transmission and reception. The original relays obviously cannot meet these needs of people.

The relay is usually used in automatic control circuits. It is actually an "automatic switch" that uses a smaller current to control a larger current. Therefore, it plays the role of automatic adjustment, safety protection, and conversion circuit in the circuit.

The coil is energized → magnetic flux is generated → electromagnetic attraction → the armature is attracted to the iron core → the armature drives the contact to act → the relay is excited (suction ↑)

The coil is powered off → the attractive force is reduced → the armature is dropped by gravity → the relay loses its magnetism (dropped ↓)

1. The distinction between "normally open, normally closed" contacts of relays:

The static contact that is in the open state when the relay coil is not energized is called a "normally open contact" and is represented by the letter H;

The static contact in the ON state is called a "normally closed contact" and is represented by the letter D.

The other is that a moving contact and a static contact are normally closed, and at the same time are normally open with a static contact, forming an open and closed switching contact form, which is represented by the letter I.

The relay generally has two sets of circuits, namely a low-voltage control circuit and a high-voltage working circuit.

Telecom Relay

Telecom Relay

As a Telecom Relay Supplier, share with you the basic principles of relays:

1. Rated working voltage.

The voltage required by the coil for normal relay operation.

Depending on the type of relay, it can be either AC voltage or DC voltage.

2. DC resistance.

The DC resistance of the coil in the relay can be tested with a multimeter.

3. Pull-in current.

The minimum current at which a relay can generate a pull-in action.

In normal use, the given current must be slightly larger than the pull-in current, so that the relay can work stably. As for the working voltage applied to the coil, generally do not exceed 1.5 times the rated working voltage, otherwise a larger current will be generated and the coil will be burned. We also have Telecom Relay on sale, welcome to consult.


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