Chapter 5 Control System Fault Handling-KIMAIR.-The source of power for air compressors

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Section 1 PLC Fault Troubleshooting

The PLC (Programmable Logic Controller) is the core component of the KIMAIR air compressor control system, responsible for coordinating and controlling the operation of the entire system. When a PLC fails, it can prevent the compressor from working properly and may lead to more severe equipment damage. Therefore, timely and accurate PLC fault troubleshooting is crucial. 1.1 Common PLC Fault Symptoms ▪ System cannot start: The PLC does not receive the start signal, causing the compressor to fail to start. ▪ Abnormal operation: Frequent shutdowns or unstable operation during the compressor’s run. ▪ Frequent alarms: The PLC triggers frequent alarms, but no obvious faults are found in other components upon inspection. ▪ Data loss: The operation data stored in the PLC is lost, preventing the system from recording and monitoring the operating status properly. 1.2 Fault Troubleshooting Steps 1.2.1 Check power supply and grounding ▪ Power supply check: Use a multimeter to check whether the PLC’s input voltage is normal and ensure the voltage is within the allowed range. Common power issues include low voltage, voltage fluctuations, or poor contact in the power supply line. ▪ Grounding check: Ensure the PLC is properly grounded. Poor grounding can lead to interference with the PLC’s internal circuits, affecting normal operation. Inspect the grounding wire for looseness or corrosion, and reconnect or replace it if necessary. 1.2.2 Check input and output modules ▪ Input module check: Use a multimeter or PLC diagnostic tool to check whether the input module signals are functioning normally. Common input faults include abnormal sensor signals, poor switch contacts, or short circuits in the wiring. ▪ Output module check: Inspect whether the output module’s load, such as relays or contactors, is working properly. Faults in the output module may cause the load to fail to start or operate correctly. 1.2.3 Check communication lines ▪ Communication interface check: Verify that the communication interface between the PLC and the host computer or other devices is functioning properly. Common communication issues include damaged communication cables, loose interfaces, or incorrect communication protocol settings. ▪ Network topology check: Ensure the PLC network topology is reasonable, with no loops or breakpoints in the network. Use network diagnostic tools to check the connection status and rule out network faults. 1.2.4 Check programs and firmware ▪ Program check: Use programming software to verify that the PLC’s program is correct and free from logic or syntax errors. Common program issues include version mismatches, lost or altered programs. ▪ Firmware check: Check whether the PLC’s firmware version is up to date and update it if necessary. An outdated firmware version may limit the PLC’s functionality or cause compatibility issues. 1.3 Fault Troubleshooting Methods ▪ Restart the PLC: Sometimes, a simple restart can resolve temporary issues, such as memory overflow or program freezes. ▪ Backup and restore: Before troubleshooting, back up the PLC’s program and data. If significant issues are found during troubleshooting, the backup can be restored to prevent data loss. ▪ Replace modules: If a module is found to be damaged, it should be replaced promptly with a new one. When replacing modules, ensure that the model and version of the new module match the original. ▪ Professional repair: For complex or difficult-to-resolve faults, it is recommended to contact professional repair personnel. They have extensive experience and specialized tools to more accurately diagnose and repair faults.

Section 2 Sensor Failure Handling

Sensors are an essential part of the KIMAIR air compressor control system, responsible for collecting various operating parameters such as temperature, pressure, and flow rate. When sensors fail, the control system cannot accurately monitor and control the compressor's operation, affecting the equipment's normal operation. 2.1 Common Symptoms of Sensor Failure ▪ Abnormal data: The data collected by the sensor significantly deviates from the actual value, such as the temperature sensor showing a temperature much higher or lower than the actual temperature. ▪ No data output: The sensor fails to output data, and the control system cannot acquire the relevant parameters. ▪ Frequent alarms: Sensor faults trigger frequent alarms in the control system, affecting the normal operation of the equipment. ▪ Unstable operation: Abnormal sensor data causes the control system to be unable to accurately control the compressor’s operation, leading to frequent starts and stops or unstable operation. 2.2 Troubleshooting Steps 2.2.1 Check sensor connections ▪ Line check: Inspect the connection lines between the sensor and the PLC for looseness or damage. Common line issues include cable breakage, loose connections, or poor contact. ▪ Connector check: Inspect the sensor connectors to ensure they are secure and free from corrosion or oxidation. If necessary, reconnect or replace the connectors. 2.2.2 Check the sensor itself ▪ Visual inspection: Check the sensor for visible damage, such as cracked housing or exposed wiring. Physical damage may lead to internal circuit damage in the sensor. ▪ Function testing: Use multimeter or other testing tools to check if the sensor is functioning properly. Common tests include measuring the sensor’s output signal and testing its response time. 2.2.3 Check the control system ▪ Parameter settings: Check that the sensor's parameter settings are correct, ensuring that its working range and accuracy meet the requirements. Common parameter setting issues include incorrect range settings or low resolution. ▪ Calibration: Regularly calibrate the sensor to ensure its measurement accuracy. During calibration, use standard instruments to compare and adjust the sensor's output value. 2.3 Fault Troubleshooting Methods ▪ Clean the sensor: For sensors that are polluted or have accumulated dust, use a clean cloth or specialized cleaning agent. Avoid using corrosive or highly volatile cleaners to prevent damaging the sensor during cleaning. ▪ Replace the sensor: If the sensor is found to be damaged, it should be replaced promptly with a new one. Ensure that the new sensor's model and specifications match the original sensor. ▪ Adjust the installation position: For sensors that are incorrectly installed, adjust their installation position. Ensure that the sensor is installed in a suitable location to avoid interference or temperature changes. ▪ Professional repair: For complex or difficult-to-solve issues, it is advisable to contact professional repair personnel. They have extensive experience and specialized tools to more accurately diagnose and repair faults. By following these steps, PLC and sensor faults can be effectively diagnosed and resolved, ensuring the proper operation of the KIMAIR air compressor control system, improving equipment reliability and stability.