When a VFD has an abnormal protection (Fault), the system usually stops output to protect the equipment. At this time, you need to first check the error code displayed on the VFD to confirm the cause of the fault, such as overcurrent, overvoltage, undervoltage, or overload. After eliminating the cause of the fault, you can clear the fault state through the Reset button on the operation panel, external control terminals, or by cycling the power. After the reset is completed, restart the VFD operation. If the fault continues to occur, it is recommended to check whether the load condition, power quality, and related wiring are normal.
 

A VFD overcurrent is usually caused by excessive load, motor failure, too short an acceleration time, or an output short circuit. Troubleshooting methods include checking whether the load is too heavy, confirming the status of the motor and cables, extending the acceleration time, and checking whether the system wiring is normal, or further turning off the power and disconnecting the motor wires to measure the motor insulation impedance and whether the phase-to-phase impedance of the motor wires is balanced.
 

A VFD overvoltage often occurs when deceleration is too fast or the load inertia is too large, at which time the motor will generate regenerative energy fed back to the VFD, causing the DC bus voltage to rise. Solutions include extending the deceleration time, installing a braking resistor, or adjusting control parameters.

Additionally, the following reasons may also generate an OE error signal:

1. Is there any SCR equipment near the power input terminal?
2. Are there any large-capacity drive devices sharing the same power supply with the VFD? ex: (Air compressors performing start and stop actions)
3. Excessive power fluctuation
4. Is the deceleration time too short?

If any of the above reasons occur, please install an AC reactor at the VFD input terminal.

A VFD showing an LE1 low voltage (Undervoltage) fault is usually caused by the input power supply voltage being too low, excessive power fluctuations, insufficient power supply capacity, or poor contact of the power cord. When the VFD detects that the DC bus voltage is below the safe range, the system will initiate a protection mechanism to prevent equipment damage.
Troubleshooting methods include checking whether the power supply voltage is normal, confirming whether the power cords and terminal wiring are secure, and checking whether the power supply system has instantaneous voltage drops.
 

When the VFD displays GF (Ground Fault), it means there may be a short to ground or leakage situation at the output terminal or motor system. Common causes include motor insulation damage, damaged motor cables, wiring errors, or a humid environment causing leakage.
Troubleshooting methods include: checking whether the motor and cable insulation is normal, confirming whether the wiring is correct, measuring the insulation resistance to ground (the motor insulation must have an impedance of more than 100Mohm at DC500V), and checking if there is moisture or pollution causing leakage. If the fault still persists, it is recommended to stop operation and have a professional technician check further.
 

It is not recommended to perform a VFD withstand voltage test or insulation resistance test yourself, because the voltage of the testing instruments is as high as 500V~2000V, and incorrect measurement methods on the VFD may cause severe damage to the VFD.
If a motor insulation resistance measurement is to be performed, the VFD and motor wires must be disconnected first, and the insulation impedance measurement must be performed solely on the motor side according to the steps in the VFD operation manual to avoid damaging the VFD.
 

When a VFD is operating, it generates high-frequency switching signals that may interfere with other equipment, such as PLCs, sensors, or communication equipment, through power lines or electromagnetic radiation. To reduce VFD electromagnetic interference (EMI), the following measures can be taken:

1. Use shielded motor cables and ground them correctly.
2. Install EMI filters or reactors at the input or output terminal.
3. Route power lines and control lines separately.
4. Shorten motor cable length and ensure good grounding.
5. Lower the VFD carrier frequency if necessary.

Through appropriate installation and wiring methods, VFD interference with other equipment can be effectively reduced.
 

VFDs generate high-frequency leakage currents during operation, mainly from the filter capacitors and electromagnetic interference suppression circuits on the output side of the VFD, so when using a general 30mA sensitivity earth leakage circuit breaker (RCD/ELCB), it is prone to false tripping.
Troubleshooting methods include: selecting a high-frequency tolerant or VFD-specific earth leakage circuit breaker suitable for VFDs, appropriately increasing the leakage protection current value (such as 100mA or above), confirming the grounding system is normal, and shortening the motor cable length or using shielded cables to reduce the impact of leakage current and electromagnetic interference.
 

During light load or no-load operation, a slight unbalance in the VFD three-phase input current is usually a normal phenomenon. This is caused by the internal rectification and capacitor charge/discharge characteristics of the VFD, as well as the current fluctuations being more obvious when the load is small; as the VFD output load increases, the situation of three-phase input current unbalance will gradually narrow.
As long as the current difference is not large and the equipment operates stably, it usually does not affect system operation. But if the three-phase current difference is too large, it is recommended to check whether the input power quality, wiring status, or equipment load is normal.