The DCS control system is actually the same as a computer. If it is not maintained regularly, it can easily affect the stability of performance and greatly reduce its service life. Therefore, it is necessary to improve the system margin, diagnostic software, and load measurement system to prevent DCS failures during operation. So what faults will occur in DCS? What measures should be taken again? Let’s take a look together!
- Communication network failure: Communication network failures are generally prone to occur at the contact bus, local bus, or due to incorrect address identification.
- Node bus failure: The transmission medium of the node bus is generally coaxial cable, some use token signal transmission, while others use conflict detection based multi-channel transmission of competing bus signals. Regardless of the method used, any interruption at any point on the main line of the bus will cause communication failures among all stations and their sub devices on the bus.
- Local bus fault: Local bus or fieldbus is generally a data communication network composed of twisted pair cables. Due to the fact that the connected equipment is a primary component or control device directly connected to the production process, the working environment is harsh, the failure rate is high, and it is easily affected by the misoperation of maintenance personnel, which can affect the production process
- Error in address labeling: Whether it is a local component or a bus interface, once its address labeling is incorrect, it will inevitably cause communication network disorder. So, it is necessary to prevent address identification failures of each component and prevent human errors and modifications.
- Hardware failure: DCS system can be divided into human-machine interface failure and process channel failure according to the different functions of each hardware.
- Human error: During maintenance or troubleshooting of the system, there may be human errors, which can occur for personnel who frequently perform system maintenance or are new to system maintenance. Generally, when modifying control logic, downloading software, restarting devices, or forcing devices, protection signals are the most prone to misoperation events.
- Power failure: There are also many issues with the power supply, such as the inability of the backup power supply to automatically switch, unreasonable insurance configuration, and internal faults of the power supply causing power interruption. Fluctuations in the stabilized power supply can lead to protection misoperation and poor contact of the plug, resulting in no output from the stabilized power supply; Some systems have an entire cabinet that is supplied with all input signals through a fuse or an external power supply with a large load, and the control power supply is not connected or has redundant backup.
- Malfunctions caused by interference: There are also many examples of malfunctions caused by interference. The interference signal of the system may come from the system itself or from the external environment. Due to strict requirements for grounding in different systems, if the grounding resistance or grounding method does not meet the requirements, it will reduce the efficiency of network communication or increase the possibility of errors, which may cause some functions to malfunction or even network paralysis.
