What is a safety relay?

Update:19-11-2020
Summary:

The safety relay is a combination of several Latching R […]

The safety relay is a combination of several Latching Relays and circuits in order to complement each other's abnormal defects and achieve the complete function of the correct and low malfunction relay. The lower the error and failure value, the higher the safety factor. Therefore, it is necessary to design a variety of safety relays to protect different levels of machinery, and the main goal is to protect machine operators who are exposed to different levels of danger.

The so-called "safety relay" is not a "relay without failure", but a regular action when a failure occurs. It has a forced-oriented contact structure, which can ensure safety in the event of contact fusion. This is the same as general The relay is completely different.

The safety relay is a necessary control part in a safety circuit. It accepts safety inputs and, through the judgment of the internal circuit, outputs a switch signal deterministically to the control circuit of the device. Simply put, safety relays are all dual-channel signal types. The safety relay can only work normally when the signals of both channels are normal; during the working process, as long as any of the channel signals is disconnected, the safety relay will stop outputting until both All channel signals are normal and can work normally after reset.
Claim

1. When the emergency stop is released, the machine cannot restart suddenly;
2. In case of machine safety circuit failure, the machine power supply can be stopped;
3. When the safety circuit fails, the machine cannot be restarted;

Duplication alone will not work.
Duplication is necessary, but in addition, for example, the following conditions, the mutual inspection of the duplex circuit, confirm that all safety circuits have been disconnected once, and if necessary, the operator can start the operation. From another perspective, when the input switch wiring is short-circuited or the wire sheath is damaged, it is necessary to prevent the sudden start of the machine.
In fact, in order to facilitate the construction of the safety circuit, the safety relay is combined with other components, and the basic emergency stop circuit and the safety circuit are called the safety relay module.
use
It is used in the design of a safety circuit with an input to confirm the safety of the machine, and after the safety is confirmed, the input of the contactor, etc. is controlled.