1. Power Supply Issues
Unit does not power on: Check the main circuit breaker, fuses, and power cord for open circuits or loose connections. Note that phase sequence errors or missing phases often occur after relocating used equipment.
Frequent tripping: This is typically caused by aging insulation leading to leakage current or a motor short to ground. Use a megohmmeter to measure the insulation resistance (replace the wiring if the reading is below 0.5 MΩ).
2. Temperature Control System Malfunction
Temperature does not rise: Open circuit in the heating coil, damaged solid-state relay (SSR), or burnt-out contactor contacts. Use a multimeter to measure the resistance of the heating coil and the output voltage of the SSR.
Temperature overshoot: PID control not tuned or SSR contacts stuck. Perform an auto-tuning cycle; if ineffective, replace the SSR.
Display fluctuates or shows "HHH/LLL": Thermocouple break or loose compensation leads. Swapping the thermocouples in the normal zone can quickly pinpoint the issue.
3. Inverter and Drive Faults
No display on the inverter: Check for a missing phase in the input power supply; the internal switching power supply or rectifier module may be faulty. For older inverters, it is recommended to replace the entire unit to prevent unexpected shutdowns.
Motor Does Not Rotate and Alarms (Phase Loss, Overcurrent): The motor windings may be burned out or the cables damaged. Disconnect the wires and measure whether the resistance values of the three phases are balanced. Also verify the inverter parameters (such as motor power and acceleration/deceleration times).
Overvoltage During Deceleration: The deceleration time is too short. For high-inertia loads, extend the deceleration time or install an external braking resistor.
4. Sensor and Actuator Malfunctions
No signal from proximity/photoelectric switches: Sensing distance has shifted or internal damage. Replacement is cost-effective; repair is not recommended.
Solenoid valve fails to actuate: Coil burnout or PLC output point failure. Measure the coil resistance (tens to hundreds of ohms); if normal, check the output relay.
Key Maintenance Tips
Most electrical faults in used equipment stem from loose connections, oxidized terminals, and aging components. Prioritize tightening all terminal connections and cleaning dust from the electrical cabinet.