Relay characteristics of relays, circuit principles of relays

Infineon / Mitsubishi / Fuji / Semikron / Eupec / IXYS

Relay characteristics of relays, circuit principles of relays

Posted Date: 2024-01-30

The relay characteristics of a relay refer to the characteristics displayed by the relay during operation, which mainly include the following aspects:

Isolation: The relay can isolate the control loop and the controlled loop when working, thereby avoiding the impact of high voltage or high current on the control loop.

Amplification: Relays can convert weak control signals into larger output signals to control high-power equipment.

Stability: The output state of the relay should remain stable without a control signal, and the stability of the output state should also be maintained during continuous switching operations.

Delay characteristics: Due to the inertia of the relay mechanism and the electromagnet, the relay can reach a steady state within a certain period of time after being excited. This time is the action time of the relay. Similarly, after the control signal is disconnected, the relay also needs a certain amount of time to return to its normal state. This time is the release time of the relay.

Safety: Relays should have certain safety protection functions during operation. For example, in the event of overload, short circuit, overvoltage, etc., they should be able to cut off the circuit in time to avoid harm to equipment and personnel.

Relay circuit principle

A relay is an electrically controlled mechanical switching device. Its circuit principle can be simply described as: when the control circuit of the relay is energized, the electromagnet inside the relay will generate electromagnetic force, causing the mechanical contactor to attract or disconnect, thereby achieving Circuit switch.

Specifically, a relay usually consists of a control circuit and a controlled circuit. Among them, the control circuit generally consists of a power supply, a control switch and an electromagnet, and the controlled circuit consists of a contactor and a load.

In the initial state, the electromagnet of the relay is not activated, the contactor is in the open state, and the circuit is in the open state. When the control circuit is energized, the electromagnet generates a magnetic field, causing the contactor to close, thus connecting the controlled circuit and the load, and the circuit is in a closed state. When the control loop is terminated, the electromagnet loses its magnetic field, the contactor returns to the open state, and the circuit is in the open state again.

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