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How does the safety relay work?
- Jul 09, 2018 -

The safety relay is composed of several relays and circuits in order to complement each other's abnormal defects and achieve the complete function of the correct and low malfunction relay, so that the lower the fault and the failure value, the higher the safety factor. Therefore, a variety of safety relays must be designed to protect different grades of machinery, the main goal is to protect the mechanical operators exposed to different levels of danger.

What are the main differences between safety relays and general relays?

The so-called "safety relay" is not a "no fault relay", but a regular action when a fault occurs. It has a forced guiding contact structure, which ensures safety even in the event of contact sintering. The relays are completely different.

Where is the safety relay used?

It is used in the design of a safety circuit that controls the input of a contactor, etc., after confirming the safety with an input confirming the safety of the machine.

Q: Requirements for safety circuits

1. When the emergency stop is released, the machine cannot suddenly restart.

2. In case of failure of the machine safety circuit, the machine power supply can be stopped.

3. When the safety circuit fails, the machine can no longer be started.

If the security switch, light curtain, etc. confirm the safe input, the above functions cannot be achieved. Then, how can the safety circuit be implemented? When is the dual circuit?

A: It is impossible to rely on dualization alone.

Dualization is necessary, but in addition to this, the dual circuit is checked against each other to confirm that all safety circuits have been disconnected once, and if necessary, the operator can start the conditions. Also, from another point of view, when the input switch wiring is short-circuited or the possibility of grounding due to breakage of the wire sheath, the sudden start of the machine must be prevented.

In fact, in order to facilitate the construction of the safety circuit, the safety relay and other components are combined, and the basic emergency stop circuit and the safety circuit are called the safety relay module.