"redundancy design" of PLC control system - Solutions - Huaqiang Electronic Network

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The "redundant design" of the plc control system is mainly applied to two aspects. One is the "redundant design" of the control circuit, such as the emergency breaking circuit, etc.: The second is the "redundant design" of the PLC itself.
The so-called "redundant design" of the control circuit is to prevent the safety and reliability accidents caused by the failure of a certain component in order to ensure its safety and reliability, and to increase the artificially unnecessary under normal circumstances. Measures such as “excessive” control of the device and repeated use of contacts improve line reliability.
For contactors for emergency disconnection, the contacts of several contactors must be operated simultaneously to achieve "redundancy", ensuring that the safety circuit remains effective even when one contactor fails.
The purpose of PLC "redundant design" is to further improve the system's operational reliability and avoid downtime and safety accidents due to PLC failure.
The “redundant” system, also known as the “hot backup” system, is mainly used for occasions where safety and reliability are very high, such as large production lines and chemical equipment, which may cause major safety and quality accidents due to PLC shutdown.
PLC "redundancy" requires a CPU system with "redundancy" function, such as SIEMENS S7-400H. In order to realize the "redundancy" of the PLC, two sets of identical power supply, communication, CPU and other modules need to be configured in the system. The two systems work at the same time, one set (main system) is used for normal control; the other set (Alternate system) Run the same control program, but its output is disabled. When the main system fails, the standby system immediately takes over the control of the system and becomes the main system to ensure the normal operation of the equipment. At the same time, the maintenance personnel can repair and repair the faulty system, and then load into the system to become the standby system after the repair is completed. This continuous work alternates to ensure that the system does not stop working continuously.