If the PLC control cabinet is poorly grounded, the following series of adverse effects will occur:
- Interference problem
Increased electromagnetic interference:
Poor grounding will make the PLC control cabinet more susceptible to external electromagnetic interference. For example, the electromagnetic field generated by nearby high-voltage transmission lines, high-power motors, inverters and other equipment may couple into the PLC system and interfere with its normal operation.
Electromagnetic interference may cause errors in the input signal of the PLC, resulting in malfunction or unstable control output. For example, the signal of the sensor may be interfered and become inaccurate, affecting the control system’s monitoring and control of the production process.
Signal distortion:
Poor grounding can make the ground potential in the signal loop unstable, resulting in signal distortion. For analog signals, such as the output signals of sensors such as temperature, pressure, and flow, fluctuations in ground potential may reduce the accuracy of the signal and even produce erroneous measurement results.
Digital signals may also be affected, resulting in errors such as bit errors and data transmission errors, affecting the communication between PLC and other devices.
- Safety hazards
Increased risk of electric shock:
Poor grounding may cause the metal casing of the PLC control cabinet to carry dangerous voltages, increasing the risk of electric shock. If the operator touches the charged casing, it may cause an electric shock accident, posing a serious threat to personal safety.
Especially in a humid environment or when there is a leakage of conductive liquid, the risk of electric shock will increase further.
Risk of equipment damage:
Poor grounding may cause overvoltage shocks, damaging PLC and other electronic equipment. For example, in thunderstorms or power grid failures, control cabinets without good grounding are more susceptible to overvoltage, which may damage key components such as the input and output modules and power modules of the PLC.
Long-term poor grounding may also cause the insulation performance of the equipment to deteriorate, accelerating the aging and damage of the equipment.
- System stability issues
Unstable control:
Poor grounding will affect the stability of the PLC control system, causing fluctuations or instability in the control process. For example, the speed of the motor may be unstable, and the opening of the valve may change abnormally, affecting the stability of the production process and product quality.
Unstable control may also cause the system to frequently alarm or shut down, affecting production efficiency.
Communication failure:
Poor grounding may affect the communication between the PLC and other devices. For example, the communication between the PLC and the host computer may be interrupted, data may be lost, and other problems may occur, affecting the normal operation of the monitoring and management system.
Communication failure may also cause the control system to be unable to respond to external instructions in a timely manner, affecting the coordination and control of the production process.
In short, the impact of poor grounding on the PLC control cabinet is multifaceted, which will not only affect the performance and stability of the system, but also bring safety hazards. Therefore, when installing and maintaining the PLC control cabinet, it is necessary to ensure good grounding to ensure the normal operation of the system and the safety of personnel.
