PLC routine maintenance and repair - Solutions - Huaqiang Electronic Network

Brand AVX TPSE226M035R0125 Low impedance tantalum capacitor AVX 22

Electronic scale crystal oscillator 3.2*2.5mm 3225 16M (16.000MHZ) 12PF 10PPM 20PPM 30PPM

Photocoupler

(1) Inspection of the power supply. The quality of the power supply directly affects the reliability of the use of the plc, and is also a component with a high failure rate. Check whether the voltage meets the range of 85% to 110% of the rated range and whether the voltage fluctuation is frequent.
(2) Inspection of the operating environment.
(1) PLC operating environment temperature is 0 ~ 60 °C. Excessive temperature will degrade the performance of the internal components of the PLC and increase the number of faults. In particular, the CPU will reduce the life of the PLC due to the acceleration of the "electron migration" phenomenon. When the temperature is low, the safety factor of the analog circuit will also become small, and the ultra-low temperature may cause the control system to malfunction. The solution is to install a suitable axial fan in the control cabinet or install an air conditioner, and pay attention to frequent inspections.
(2) The relative humidity of the environment is between 5% and 95%. In a high humidity environment, moisture easily intrudes into the interior through defects in the metal surface of the IC on the module, causing deterioration of internal component performance, lowering internal insulation performance, causing short circuit due to high voltage or surge voltage; extremely dry Under the circumstances, MOS integrated circuits will cause breakdown due to static electricity.
(3) Regularly purify the internal dust to ensure the smooth flow of the air duct and the insulation of the components.
(4) Check the installation status of the PLC. Whether each PLC unit is fixed firmly, whether the terminals of various I/O modules are loose, whether the connector of the PLC communication cable is fully inserted and tightened, and whether the external connection line is damaged.
(5) Check if the battery of the program memory of the PLC needs to be replaced. (three) PLC maintenance
The PLC controller has a certain self-checking capability and has a self-diagnosis processing phase in the system operation cycle. Therefore, during the maintenance process, it should:
(1) Check if the PLC power supply is normal. If the POWER indicator is off, check the power supply line and fuse.
(2) Check the PLC system. Start the PLC to check whether the "RUN" indication is normal and whether there is an alarm. This type of failure is difficult for PLC systems that are usually in use.
(3) Inspection of the I/O module. Check whether the power supply voltage of the I/O module is normal. Check whether the signal of the input/output port and the corresponding port indicator are normal.