What are the common fault codes of Mitsubishi VFD and their solutions?

As a trusted supplier of Mitsubishi Variable Frequency Drives (VFDs), I've had the privilege of working closely with these high - performance devices. Over the years, I've encountered numerous common fault codes that users may face. Understanding these fault codes and their solutions is crucial for maintaining the smooth operation of Mitsubishi VFDs. In this blog, I'll share some of the most prevalent fault codes and how to address them.

1. E.OC (Over - Current)

The E.OC fault code indicates that the inverter has detected an over - current condition. This can be a serious issue as it may lead to damage to the inverter if not resolved promptly.

Possible Causes

Motor short - circuit: A short - circuit in the motor windings can cause excessive current flow. This could be due to insulation breakdown over time, physical damage to the motor, or moisture ingress.
Excessive load: If the motor is driving a load that is beyond its rated capacity, the inverter will draw more current to try and maintain the required speed. This can happen if the mechanical system has seized or if there is a blockage in the driven equipment.
Inverter internal problems: Faulty power modules, current sensors, or control boards within the inverter can also trigger an over - current fault.

Solutions

Check the motor: Use a multimeter to measure the resistance between the motor windings. If the resistance is extremely low or zero, it indicates a short - circuit, and the motor may need to be repaired or replaced.
Reduce the load: Inspect the mechanical system for any signs of blockage or seizure. If necessary, adjust the load to be within the motor's rated capacity.
Inverter inspection: If the motor and load are in good condition, it may be an internal issue with the inverter. In this case, it is recommended to contact a professional technician for further diagnosis and repair. You can explore our Mitsubishi Fr - e720 - 0.4k Inverter for a reliable replacement option.

2. E.OV (Over - Voltage)

The E.OV fault code means that the DC bus voltage of the inverter has exceeded the allowable limit. This can be caused by several factors.

Possible Causes

Regenerative braking: When the motor decelerates rapidly, it acts as a generator and feeds back energy into the DC bus. If the braking resistor is not properly sized or functioning, the DC bus voltage can rise to dangerous levels.
Power supply voltage fluctuations: Unstable power supply with high voltage spikes can also cause the DC bus voltage to exceed the limit.
Faulty voltage detection circuit: A malfunction in the inverter's voltage detection circuit can lead to false over - voltage alarms.

Solutions

Check the braking resistor: Ensure that the braking resistor is properly connected and has the correct resistance value. If necessary, replace the braking resistor with a suitable one.
Stabilize the power supply: Use a voltage stabilizer or surge protector to protect the inverter from power supply fluctuations.
Inspect the voltage detection circuit: If you suspect a problem with the voltage detection circuit, it is best to have a professional technician check and repair it. Consider our Mitsubishi FR - D740 - 1.5K - CHT VSD/VFD which has advanced voltage regulation features to minimize such issues.

3. E.TH (Over - Temperature)

The E.TH fault code indicates that the inverter has overheated. Over - temperature can damage the inverter components and reduce its lifespan.

Possible Causes

Poor ventilation: If the inverter is installed in an enclosed space with inadequate ventilation, heat cannot dissipate effectively, leading to over - heating.
High ambient temperature: Operating the inverter in an environment with a high ambient temperature can also cause it to overheat.
Excessive load: Running the inverter at a high load for an extended period can generate more heat than it can dissipate.

Solutions

Improve ventilation: Ensure that the inverter has sufficient clearance around it for proper air circulation. You can also install fans or cooling ducts to enhance ventilation.
Control the ambient temperature: If possible, relocate the inverter to a cooler environment or use air - conditioning to maintain a lower ambient temperature.
Adjust the load: If the inverter is overloaded, reduce the load or upgrade to a higher - capacity inverter. Our FR - E740 - 0.4K - CHT Mitsubishi E700 Series Inverter is designed with efficient cooling systems to handle various load conditions.

4. E.PU (Power Supply Loss)

The E.PU fault code means that the inverter has detected a loss of power supply. This can disrupt the normal operation of the motor.

Possible Causes

Power cable issues: Loose connections, damaged cables, or blown fuses in the power supply circuit can cause a power loss.
Power supply failure: Problems with the main power source, such as a tripped circuit breaker or a faulty transformer, can also lead to this fault.

Solutions

Check the power cables: Inspect the power cables for any signs of damage or loose connections. Tighten the connections and replace any damaged cables.
Verify the power supply: Check the main power source, including the circuit breaker and transformer. Reset the circuit breaker if it has tripped or have the transformer repaired if necessary.

5. E.GF (Ground Fault)

The E.GF fault code indicates that there is a ground fault in the system, which means that there is an unintended electrical connection between the electrical circuit and the ground.

Possible Causes

Insulation breakdown: Damaged insulation in the motor or cables can cause a ground fault. This can be due to aging, mechanical stress, or environmental factors.
Moisture ingress: Water or moisture in the electrical system can create a conductive path to the ground, leading to a ground fault.

Solutions

Inspect the insulation: Use an insulation resistance tester to check the insulation resistance of the motor and cables. If the insulation resistance is low, replace the damaged components.
Remove moisture: If moisture is suspected, dry the electrical system thoroughly and take measures to prevent future moisture ingress, such as installing waterproof enclosures.

In conclusion, being aware of these common fault codes and their solutions can help you troubleshoot Mitsubishi VFDs effectively. However, if you encounter complex issues or are unsure about the diagnosis and repair process, it is always advisable to seek professional assistance.

As a leading supplier of Mitsubishi VFDs, we are committed to providing high - quality products and excellent after - sales service. Whether you need a replacement inverter or technical support, we are here to help. If you are interested in purchasing Mitsubishi VFDs or have any questions, please feel free to contact us for a detailed discussion and personalized solutions.