Foxboro H929049B0500 control module

Description

PLC has been widely used in the water supply industry due to its advantages such as strong functionality, brief program design, and easy maintenance, especially its high reliability and strong ability to adapt to harsh industrial environments. However, due to harsh on-site environmental conditions, high humidity, and various industrial electromagnetic and radiation interferences, which can affect the normal operation of the system, it is necessary to pay attention to the anti-interference design of the project.

The interference sources of PLC in water plant applications mainly include interference introduced by the power system, interference introduced by the grounding system, and interference introduced by the input and output circuits. If the interference problem with the PLC is not resolved properly, the system will not be able to operate reliably and will affect normal water supply. Therefore, it is necessary to explore the interference issues in PLC application systems. This article mainly discusses three anti-interference technologies of PLC.

Analysis of Technical Countermeasures for Anti interference
To prevent interference, hardware and software anti-interference measures can be adopted, among which hardware anti-interference is the most basic and important anti-interference measure. Generally, interference sources are suppressed and eliminated from both anti-interference and prevention aspects, cutting off the coupling channel of interference to the system, and reducing the sensitivity of the system to interference signals.

1. Interference introduced by the power system
The interference of the power grid and frequency fluctuations will directly affect the reliability and stability of the PLC system. How to suppress interference in the power system is the main link to improve the anti-interference performance of PLC.

(1) Install a filtering, isolation, shielding, and switch regulated power supply system.
The purpose of setting a filter is to suppress the transmission of interference signals from the power line to the system. When using an isolation transformer, it must be noted that the shielding layer should be well grounded; The secondary connecting wire should use double wound wires (to reduce interference between wires), and the primary and secondary windings of the isolation transformer should be separately shielded. The primary shielding layer should be connected to the zero line of the AC power grid; The secondary shielding layer and the primary interlayer shielding layer are connected to the DC terminal.

In order to suppress the fluctuation of power grid voltage caused by the start and stop of large capacity equipment in the power grid (such as water supply pumps) and maintain stable power supply voltage, a starting stabilized power supply can be used.

(2) Separate power supply system
The PLC controller and I/O system are powered by their respective isolation transformers and separated from the main power supply, so that when the input and output power supply is cut off, it will not affect the power supply of the controller.

TY223001-AL
YT223001-AM
YT204001-HS
3ASD399002A17
YT204001-DL
YT204001-JN
4890072-AA
YT204001-BT
YT204001-AD
YT204001-DP
YT296000-MC
YXU-144
YT204001-BK
YT204001-FB
YT204001-EF
YT204001-AB
YT204001-FR
YT203001-AM
YT204001-EH
YT204001-DF
YT399001-AN