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Lead Contents

Reason of Safety Relay is Required in Safety Circuit

FAQ No. FAQ02301

Primary Contents


Why is the Safety Relay required for safety circuits?


The Safety Relay is provided with a forcibly-guided contact mechanism which prevents the contact point a and the contact point b from being in operating states simultaneously when being welded, and can detect contact welding in the Safety Relay itself. It is possible to design safety circuits by using this function.

The General Relay is not provided with this forcibly-guided contact mechanism.

However, be aware that incorrect circuit design may cause the Safety Relay to be dangerous. For example, the circuit shown in the Fig-1 cannot cut off the power, and thus results in dangerous situation.

As shown in the Fig. 2, design the circuit with redundancy and configure a self-monitoring function adopting the welding check function of the forcibly-guided contact mechanism.


Part of the circuits of the Safety Relay Unit "G9S-301" (excerpt)

K1,K2,K3: Safety Relay built into the G9S-301