How to Solve the DCS Signal Interference Problem?

The reliability of the DCS control system directly affects the safe production and economic operation of industrial enterprises, and the anti-interference capability of the system is the key to the reliable operation of the whole system. At present, most of the various control systems used in automation systems are located in the harsh electromagnetic environment formed by strong current circuits and strong current equipment. At construction sites, electrical equipment, instruments, DCS control systems and signal transmission between DCS systems often interfere, causing system instability or even misoperation, which must be taken seriously.

What causes signal interference?

Material and equipment issues: The control signal connected to the DCS system usually use cables as the transmission medium to send the signal to the DCS system. When the insulation material of the signal cable is aged and the shielding material is damaged, it will be interfered with by other electromagnetic interference sources, which will cause measurement errors. error, serious interference will cause equipment damage.

Irregular construction: In the DCS control system, many signals are often connected to the DCS at the same time. These signal lines either go through cable troughs or cable tubes, causing many different types of cables to be attached to the same path on site. There are distributed capacitances between these signals, and interference will be added to other signal lines through these distributed capacitances. At the same time, alternating magnetic flux is generated in the surrounding environment where the signal is transmitted, such as power lines, motors, generators, power transformers, and relays. These magnetic fields tend to cause large disturbances.

Unreasonable grounding: The more common grounding accident is when both ends of the signal line are grounded, which will cause greater interference due to the difference in ground potential. If both ends of the signal line are grounded at the same time, there may be a large potential difference, and this potential difference may generate a large circulating current on the signal line between the two ends. Generates electromagnetic waves that interfere with signals. In addition, the total grounding resistance of the DCS system does not meet the normal working requirements of the DCS system and so on.

How to suppress signal interference?

• Ensure the normal use of signal lines: During the use of signal lines, avoid entanglement of multiple signal lines, and regularly check the signal lines, and repair and replace signal lines with damaged insulating colloids to ensure the integrity of the signal lines. Normal use, to avoid leakage and interference to the transmission signal.
• Lay the cables in layers: isolate the cables that transmit different signals, and use layered laying to control the cables to a certain extent, so as to ensure that the cables will not interact with each other. For cables that transmit the same signal, dense entanglement of lines should be avoided as much as possible. Since the computer port can perform a certain degree of precision analysis on the signal when processing the signal, if there are similar signals that interfere with each other, will affect the judgment of the computer, which will lead to analysis errors in the computer work process.
• Signal line isolation: During the operation of the equipment, a signal isolator can be added to ensure that the signals will not affect each other.

ATO signal isolator is an instrument for transmission, conversion, isolation, transmission, and operation of industrial signals in automation control systems. It can be used with various industrial sensors and field instruments to realize the extraction, transmission, and isolation of parameter signals and meet the user's in-place needs. Signal isolators are widely used in data acquisition, signal transmission and conversion, PLC, DCS, and other industrial measurement and control systems in mechanical, electrical, communication, electric power, petroleum, chemical, steel, sewage treatment, construction, and other fields.