Shanghai Chenzhu Instrument CO., LTD.
Shanghai Chenzhu Instrument CO., LTD.

What's the Difference Between a Safety Relay and an Ordinary Relay?

Jan 25 , 2024

Ⅰ. Introduction of safety relay

The so-called safety relay refers to a relay that uses a forcibly guided contact mechanism that is different from ordinary relays so that safety can be ensured even when the contacts are melted. And the operating life of the contact is more than 10 million times.

The main purpose of the forcibly guided contact mechanism is to prevent the a-contact and b-contact in the relay from operating at the same time and to provide a forcibly guided mechanism. That is to say, safety relay means to achieve automation safety. When one of the a-contacts fails, the coil is in the non-excited state, and all b-contacts must maintain an interval of 0.5 mm or more. Or when there is a failure of a b-contact, all a-contacts must be kept at an interval of 0.5mm or more when the coil is in a non-excited state. 


Ⅱ. Introduction of ordinary relay

An ordinary relay is an electromechanical device that acts as a switch to control one or more circuits using a low-power signal. It consists of a coil that, when energized, creates a magnetic field. This magnetic field attracts an armature, moving a set of contacts to open or close a circuit. Relays are used to control high-power circuits with a low-power signal, providing electrical isolation between the control and the controlled circuits. Common applications include automotive systems, industrial controls, home appliances, and telecommunication systems. Despite newer technologies, ordinary relays remain popular for their reliability and simplicity.

Ⅲ. What is the difference between a safety relay and an ordinary relay?

1. The overall dimension of safety relays is different from that of ordinary relays. The main difference between safety relays and ordinary relays is that "safety relays" are not "relays without faults", but make regular actions when failures occur. From studying the safety relay working principle, we can know that a safety relay is safer. They have a forcibly guided contact structure, which can ensure safety in the event of contact fusion. In that case, safety relay by CHENZHU, a reliable company specializing in automation safety and providing products like safety relay and signal conditioning electronics, is completely different from an ordinary relay.

2. The emergency stop control used in early safety protection is generally a combination of several relays to complete power-off or delayed power-off control, fault memory and reset interlock, etc. The safety relay also integrates various functions. Different types of safety relays with powerful functions and high reliability can be selected according to different protection requirements, such as a light curtain safety relay.

3. The safety relay has a special color, generally yellow. The current safety relay is reliable and sensitive, mainly used to control the power circuit. When an emergency occurs, the circuit controlled by the safety relay is disconnected by pressing the emergency stop switch to guarantee safety.

Ⅳ. What are the main applicable places for safety relays?

1. Suitable for the application of electromagnetic door lock switch to ensure the safety of the work area.

2. Suitable for the key to cooperate with the safety door switch to detect the opening and closing of the door.

3. Suitable for the safety threshold switches to detect the position of the door, the opening or closing.

4. Suitable for safety light curtains to prevent workers from entering the dangerous work area.

5. Suitable for safety mat switch to confirm that workers can safely enter the hazardous work area.

6. Suitable for emergency stop button to stop the machine operation in case of emergency.

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