Common Faults of Inverters and Their Troubleshooting Guide

1. Overcurrent Fault (Most Common, e.g., Error Codes ERR10, OC)

Common Symptoms

Typical Causes

1. Load-side issues: Short circuits or ground faults in motor windings (caused by insulation damage); jamming of mechanical transmission parts (e.g., seized bearings, overly tight belts) that leads to motor stalling.
2. Wiring issues: Loose, short-circuited, or grounded cables between the inverter and motor (e.g., damaged cable insulation touching the machine casing).
3. Parameter misconfigurations: Excessively short acceleration time (resulting in a sudden spike in motor startup current); mismatched motor rated current settings (the set value is lower than the motor’s actual rated current).
4. Hardware failures: Damaged internal power modules (e.g., IGBTs); malfunctions in current detection circuits (e.g., faulty Hall sensors).

Basic Troubleshooting

• After turning off the power, use a multimeter to measure the motor’s winding resistance—normal readings show balanced resistance across three phases with no ground short circuit.
• Check if transmission components move freely and ensure cable connections are secure and undamaged.
• Verify that the inverter’s motor parameters (rated current, voltage) and acceleration time settings match the motor’s specifications.

2. Overvoltage Fault (e.g., Error Codes OV, OU)

Common Symptoms

Typical Causes

1. Power supply fluctuations: Abnormally high grid voltage (e.g., exceeding the rated 380V ±10%); lightning strikes or harmonic interference from the power grid.
2. Regenerative power from loads: When the motor decelerates or brakes suddenly (e.g., an elevator descending, a heavy object being lowered), mechanical energy converts to electrical energy and feeds back to the inverter’s DC bus, raising the bus voltage.
3. Parameter misconfigurations: Excessively short deceleration time (preventing timely dissipation of regenerative energy); disconnected or damaged brake units/brake resistors (unable to absorb regenerative energy).
4. Hardware failures: Aging DC bus capacitors (reduced capacity, failing to stabilize voltage); faulty voltage detection circuits.

Basic Troubleshooting

• Use a multimeter to confirm the grid voltage falls within the inverter’s rated range.
• Inspect the brake unit and resistor for normal operation (no signs of burning, secure wiring).
• Extend the deceleration time appropriately and check if the fault persists.

3. Overload Fault (e.g., Error Codes OL, OH)

Common Symptoms

Typical Causes

1. Excessive actual load: The motor operates under a load exceeding its rated power for an extended period (e.g., excessive water flow in pumps, increased air resistance in fans).
2. Motor issues: Worn motor bearings (increasing operating resistance); aging stator windings (causing higher copper loss and excessive heat generation).
3. Parameter misconfigurations: The inverter’s “overload protection current” is set too low; incorrect “load type” selection (e.g., setting “fan/pump type” to “constant torque type”).

Basic Troubleshooting

• Monitor the motor current during operation—it is normal if it does not exceed 1.1 times the rated current.
• Check for abnormal noises or overheating in the motor (the housing should not exceed 70°C when touched).
• Ensure the overload protection parameters align with the motor’s rated load.

4. Overheating Fault (e.g., Error Codes OH, OH1)

Common Symptoms

Typical Causes

1. Environmental factors: High temperature in the equipment room (over 40°C, exceeding the inverter’s operating requirements); obstructions around the inverter (blocking ventilation).
2. Cooling system failures: Cooling fans clogged with dust, seized, or burned out (unable to exhaust heat); blocked heat sinks (covered in dust or oil, reducing heat dissipation efficiency).
3. Long-term overload: The motor runs at high current for extended periods, transferring heat to the inverter’s interior.
4. Hardware failures: Damaged temperature sensors (triggering false overheating alarms); abnormal heat generation in internal power modules.

Basic Troubleshooting

• Clean dust from the fan and heat sink, and confirm the fan operates normally.
• Improve ventilation in the equipment room (e.g., install exhaust fans) to keep the ambient temperature ≤ 40°C.
• Check for long-term overload issues—reduce the load or replace the inverter with a higher-power model if necessary.

5. No Output/Output Abnormality (e.g., Error Codes NO OUT, FU)

Common Symptoms

Typical Causes

1. Control signal issues: Failure to deliver the start signal (e.g., loose wiring in PLC control, faulty control panel buttons); abnormal analog reference signals (e.g., interrupted 4-20mA signals).
2. Parameter misconfigurations: Incorrect “operation mode” settings (e.g., set to “external control” without connecting an external signal); frequency reference set to 0 (or below the minimum operating frequency).
3. Hardware failures: Damaged internal switching power supplies (no control voltage output); faulty drive circuits (unable to power the power module); unengaged output contactors.

Basic Troubleshooting

• Check the wiring of the start signal and reference signal for normality (use a multimeter to measure signal voltage).
• Verify that parameters like “operation mode” and “frequency reference method” are set correctly.
• After powering off, check if the internal contactor is stuck (or use a multimeter to measure the output terminal voltage—balanced three-phase voltage should be present when the inverter starts).

6. Communication Fault (e.g., Error Codes COM, ERR30)

Common Symptoms

Typical Causes

1. Communication line issues: Loose or broken communication cables (e.g., RS485 cables); cable length exceeding limits (RS485 cables typically have a maximum length of 1200 meters by default).
2. Parameter mismatch: Inconsistent “communication protocol” (e.g., Modbus, Profibus), “baud rate,” or “parity bit” settings between the inverter and upper controller.
3. Interference issues: Communication cables run in parallel with high-voltage power cables, causing signal distortion due to electromagnetic interference (EMI).
4. Hardware failures: Damaged inverter communication interfaces (e.g., faulty RS485 chips).

Basic Troubleshooting

• Inspect communication cable wiring to ensure “positive/negative poles” (A/B lines) are not reversed, and route cables away from high-voltage power cables.
• Standardize communication parameters (baud rate, parity, address) between the inverter and upper controller.
• Use the replacement method to test the communication cable or interface (e.g., replace with a spare cable to check for hardware damage).

Summary

1. First inspect external factors such as load, wiring, and environment.
2. Then verify parameter settings to ensure they match the system requirements.
3. Finally, check internal hardware (note: hardware repair must be performed by professionals to avoid electric shock or secondary damage).