With the continuous production of safety problems in the processing of industrial production, more and more people pay more attention on it. Especially in the port machinery and crane industry, it involved in the safety problem between human and mechanical equipment. The core issue of industrial production safety is to prevent casualties and property damage accidents in industrial production. In general, the safety control system should include safety input devices (such as emergency stop button, safety door limit switch or interlock switch, safety grating or light curtain, hands control buttons, etc.), safety control of electrical components (such as safety relays, safety PLC and safety bus, etc.) and safety output control (such as contactors, relays or valves in the main circuit). Lifting, safety relays are the core products that are of interest in the application.
The so-called safety relay, it is not no fault of the relay, but make a regular action once failure. It has a mandatory guide structure to ensure safety in case of contact melting phenomenon occurs.  This point is completely different with the conventional relay.
The basic functions of the safety relay are as follows:
1. Detection function: You can confirm a safety-related request, such as pressing the "emergency stop button".
2. Evaluation Function: Confirm the safety-related request and safely initiate a response, such as turning off the start-up loop.
3. Close Function: Turn off the potential hazard, such as turning off the power supply of the downstream contactor.
4. Self-locking function: When the safety relay outlet fault signal, it will not automatically reset, need to confirm the security, manual reset. For example, press the "emergency stop button", the safety relay will not automatically reset, you need to manually reset.
5. Extended function: You can increase the expansion module, the electric shock to achieve the same security level as the main contact according to your requirements.
6. Stable working function: contact group has more than 10 million times the reliable mechanical life.
A system with a safety relay is a hardware safe system that improves security. And then through the safety relay redundancy, self-test, mutual inspection design, you can achieve a set of very safe system.