In what occasions should safety relays be used and what should be paid attention to when using them
Please note that when the relay is working normally, there is a danger of electric shock if you touch it with your hands. Please note that when installing, maintaining and troubleshooting the relay (including terminal blocks, sockets and other connecting parts), please cut off the power first. Please note that when making terminal connections, please refer to the wiring diagram in the product manual first, and then connect correctly. If the connection is wrong, it may cause unexpected malfunction, abnormal heating, fire, etc. In the event of contact bonding, poor contact, disconnection, etc., it will endanger other property or even life, please use double safety devices.
The protection input circuits of safety relays (such as safety door limit and emergency stop button) generally have 3 connections:
1. The normally closed contacts of the protection element are connected in series to the working power supply of the safety relay, and the input circuits of the safety relay itself are respectively short-circuited.
2. The normally closed contact of the protection element is connected to the single-channel input contact of the safety relay, and the dual-channel contacts are respectively short-circuited
3. The normally closed contacts of the protection element (note that each protection element needs 2 normally closed contacts) are respectively connected to the dual-channel input circuit, and the single-channel input circuit is short-circuited
It is used in the design of a safety circuit with inputs to confirm the safety of the machine, and after the safety is confirmed, the inputs of contactors, etc. are controlled. The so-called "safety relay" is not a "fault-free relay", but a regular action when a failure occurs. It has a forced-oriented contact structure to ensure safety in the event of contact fusion. This is the same as general The relay is completely different. Folding requirements
The third connection method should be paid attention to during maintenance: if one of the two normally closed contacts of a door limit is broken, it is best not to short-circuit that contact with a wire, otherwise it will cause the safety relay to fail to reset (safety relays are generally There are two kinds of reset functions: automatic and manual). When there is no spare part temporarily short-circuited, it can not be reset, as long as the safety relay is disconnected from the power supply once, it can be reset; every time the safety door with contact failure is opened, it is very troublesome Therefore, spare parts should be bought and replaced as soon as possible.
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.
