3503E TRICONEX
Properly design the grounding point and grounding device, and improve the earthing system. In addition, software means must also be utilized to improve the system’s performance. Suppressing interference introduced by power sources plays a crucial role in DCS control systems. The power interference is mainly introduced into the DCS control system through the coupling of the power supply of the DCS system (such as CPU power supply, I/O power supply, etc.) and the instrument power supply with direct electrical connection to the DCS system. At present, for the power supply of the DCS system, it is generally used with good isolation performance. However, for the power supply of the transmitter and the power supply of the instrument with direct electrical connection to the DCS system, it has not received sufficient attention. Although certain isolation measures have been taken, it is not universal enough
Therefore, online uninterruptible power supply (UPS) is often used on site to improve power supply performance. The UPS should also have strong interference isolation performance, making it an ideal power supply for DCS control systems. In order to reduce electromagnetic interference radiated by power cables, especially the feeder cables of frequency conversion devices, copper tape armored shielded power cables should be used to achieve satisfactory results and reduce electromagnetic interference generated by power lines
Different types of signals are transmitted through different cables, and signal cables should be laid in layers according to the type of transmission signal. It is strictly prohibited to use different wires of the same cable to simultaneously transmit power supply and signals, avoiding parallel laying of signal lines and power cables to reduce electromagnetic interference. Before connecting the signal to the computer, a capacitor is connected in parallel between the signal line and the ground to reduce common mode interference; Adding a filter between the two poles of the signal can reduce differential mode interference.
Due to the complexity of electromagnetic interference, it is impossible to fundamentally eliminate its impact. Therefore, in the software design and configuration of the DCS control system, anti-interference processing should also be carried out in the software aspect to further improve the reliability of the system. Some commonly used measures include digital filtering and power frequency shaping sampling, which can effectively eliminate periodic interference; Regularly correcting the reference point potential and adopting dynamic zero can effectively prevent potential drift; Adopting information redundancy technology and designing corresponding software flag bits; Using indirect jumps and setting software traps to improve the reliability of software structure.
