Common Fault Types and Handling Methods of Inverters
Common Fault Types and Handling Methods of Inverters
I. Introduction
Inverters are core speed-regulation and energy-saving equipment in modern industrial automation, and are widely used in various electromechanical drive scenarios such as fans, water pumps, machine tools, and assembly lines. Relying on variable-frequency speed-regulation technology, they enable soft starting, stepless speed regulation, and overload protection of motors [1]. However, under complex working conditions such as dust, high temperature, humidity, power grid fluctuations, and heavy-load impacts, inverters that operate for a long time are prone to faults such as electrical aging, module damage, and parameter anomalies, which directly affect production continuity and may even cause equipment damage [2].
In on-site troubleshooting of inverter faults, the key is to first distinguish between external working-condition problems and problems of the equipment itself. Most faults are not caused by quality problems of the inverter itself, but by improper adaptation to working conditions, inadequate maintenance, or unreasonable parameter settings [2].
II. Common Fault Types of Inverters
Common inverter faults are mainly concentrated in several categories: overcurrent, overvoltage, undervoltage, overload, overtemperature, and grounding leakage [1]. These faults are often interrelated: a heavy load will simultaneously induce overcurrent and overload, and poor heat dissipation will aggravate overtemperature. During handling, it is necessary to make a comprehensive judgment based on the panel fault code and the actual operating conditions [2].
III. Common Faults and Handling Methods
(I) Overcurrent Fault
Overcurrent is the most frequently occurring type of inverter fault. According to the stage at which it occurs, it can be divided into overcurrent during acceleration, deceleration, and constant speed. The main causes include: excessively short startup acceleration time settings, sudden load increase or mechanical stalling, inverter output short circuit, mismatch between inverter and motor capacity, power supply phase loss, output disconnection, motor winding short circuit or insulation damage, and damage to rectifier-side and inverter-side components [3][2].
During handling, first disconnect the motor load and conduct a no-load test run. If no-load operation is normal, the fault is mostly on the motor and cable side, and the winding insulation resistance should be measured and the cable checked for damage; if the alarm still occurs under no-load conditions, it is necessary to open the machine and inspect the IGBT module and drive circuit, and replace damaged components. At the same time, the acceleration and deceleration times can be appropriately extended, and the current-limiting protection function can be enabled for heavy-load equipment [2].
（II）Overvoltage Fault
Overvoltage mostly occurs during the deceleration or shutdown stage. When the load inertia is large and the deceleration time is set too short, the motor is in a regenerative power generation state, and the feedback energy causes the DC bus voltage to rise rapidly, triggering overvoltage protection [4][1]; in addition, excessively high input power supply voltage can also cause overvoltage [5].
The main handling methods are: extending the deceleration time; enabling the inverter's overvoltage suppression or maximum voltage controller function; for large-inertia loads that require rapid deceleration, installing a braking unit and braking resistor to consume the feedback energy [4]. Applications with potential energy loads also need to be equipped with a braking unit and braking resistor.
（III）Undervoltage Fault
Undervoltage is usually related to the power supply side. Power grid voltage fluctuations, three-phase input phase loss, excessive voltage drop due to overly long power supply lines, and burned or poor contact of power switch or contactor contacts will all cause the DC bus voltage to fall below the rated value [2]. Aging of the DC filter capacitor inside the equipment and capacity degradation will also weaken the bus voltage stabilization capability and aggravate the undervoltage phenomenon [2].
During handling, use a multimeter to detect the balance of the three-phase input voltage, troubleshoot and repair phase loss and poor contact problems; for occasions with frequent power grid fluctuations, install input reactors or voltage stabilizers; replace DC capacitors that are bulging or have obviously degraded capacity in a timely manner [2].
（IV）Overload Fault
Overload is related to a long-term high load rate, frequent starts and stops and acceleration/deceleration, mechanical jamming, and mismatch between inverter and motor capacity [6][1]. After detecting overload, the inverter will automatically limit the output and issue an alarm. Long-term overload will accelerate the temperature rise and aging of power devices and the motor.
During handling, first check the actual load size, confirm whether the mechanical transmission is flexible, and then verify the power matching between the inverter and the motor; adjust parameters such as operating frequency, acceleration/deceleration time, and protection threshold according to load characteristics, so as to avoid long-term full-load or overload operation of the equipment [1].
（V）Overtemperature Fault
Overtemperature is a common problem in occasions of long-term continuous operation, and the root cause lies in the mismatch between heat dissipation capability and internal heat generation. Damage or jamming of the cooling fan, blockage of the air duct by accumulated dust and oil, drying and cracking failure of thermal silicone grease, and excessively high ambient temperature with poor ventilation will all cause the temperature of components such as the rectifier, inverter, and braking parts to rise continuously [2][1].
During handling, first cut off the power supply, clean the dust and oil on the air duct and heat sink, check whether the cooling fan can rotate normally, replace the fan if necessary and reapply thermal silicone grease evenly; at the same time, improve the installation environment, install forced ventilation or air conditioning, and avoid closed high-temperature operation [7][1].
（VI）Grounding and Leakage Fault
Grounding faults are mostly caused by damaged cable insulation and short circuit of the motor winding to ground, and the inverter will report grounding or leakage protection tripping [3]. During handling, first disconnect the motor cable from the inverter output end, measure whether the motor insulation impedance and inter-line impedance are balanced, check whether the cable insulation layer is damaged, and power on for testing again after troubleshooting and repairing the grounding short-circuit point [7][3].
IV. Daily Maintenance and Preventive Measures
A considerable proportion of inverter faults come from the lack of daily maintenance. Compared with repair after failure, normalized preventive maintenance can significantly reduce the failure rate, and can be started from the following aspects [2]:
Power supply and line environment. Equip the power supply circuit with suitable voltage stabilization and filtering devices to suppress power grid fluctuations and harmonic interference; select output cables of appropriate specifications and control their length, and regularly detect insulation; keep the control cabinet clean and dry, lay strong-current and weak-current lines separately, and regularly tighten wiring terminals [1].
Operating parameters and load matching. Set the operating frequency, acceleration/deceleration time, torque boost, and protection threshold according to the motor rated parameters and load characteristics to avoid impact current caused by improper parameters; monitor current, voltage, temperature, and other indicators in real time during operation, and control start-stop frequency and load [1].
Tiered maintenance. Daily inspection should focus on whether there are abnormal noise, odor, and abnormal temperature rise; every quarter, cut off the power to clean dust accumulated in the cabinet, heat sink, and air duct, and tighten wiring terminals; every year, conduct in-depth inspection of DC capacitors, IGBT modules, and rectifier bridges, reapply thermal silicone grease, and back up and calibrate parameters [2].
Working condition adaptation. For dusty, humid, and corrosive working conditions, install sealed cabinets and dehumidification devices; for occasions with large power grid fluctuations and serious harmonics, equip input filters and reactors; for high-frequency start-stop loads, reasonably optimize acceleration/deceleration parameters [2].
V. Conclusion
The key points of inverter fault handling are accurate positioning, targeted handling, and prevention first. On-site maintenance should follow the process of first cutting off power and discharging, then testing, and first no-load, then on-load. When replacing power devices, components of the same specifications must be selected, and system parameters must not be modified blindly. Through standardized troubleshooting and normalized preventive maintenance, the number of inverter faults can be significantly reduced, ensuring continuous and stable operation of the production line [1][2].
References
[1] Li Dehong, Zhu Yong. Research on Analysis of Common Fault Types of Inverters and Preventive Control Measures [EB/OL]. Journal Network, 2026.
[2] Diagnosis and Maintenance Process of Common Faults in Industrial Inverters [EB/OL]. China Industrial Control Network, 2026.
[3] Fault Diagnosis and Handling of Inverters in Electrical Maintenance [J].
[4] F0002 Overvoltage Fault Handling [EB/OL]. Siemens Industry Support Center.
[5] Analysis of Common Faults in Inverter Operation and Preventive Maintenance [EB/OL]. Journal Network, 2026.
[6] Research on Overload Fault Mode Identification and On-site Handling Methods for Low-voltage Inverters [J]. Hydropower Science and Technology, 2025, 8(6): 126.
[7] A Brief Discussion on Daily Maintenance and Fault Analysis of Variable-frequency Control Technology [J].
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