Solutions To Inverter Overload Faults

Inverter overload faults typically manifest as a sustained output current exceeding the rated value. The core issue is a mismatch between load demand and the inverter's (or motor's) output capacity.

Step 1: Immediate Inspection and Initial Handling

1. Power-off Reset: While ensuring safety, attempt to disconnect the inverter from the power supply, wait a few minutes, and then reconnect it. Sometimes this may be due to transient interference or a false alarm.

2. Record Key Information: Record the fault code, the operating frequency at the time of occurrence, the current, and the load conditions.

3. Check the Load Conditions: Inspect the mechanical parts connected to the motor, checking for any abnormal heaviness or jamming.

Check the mechanical equipment for blockages, wear, insufficient lubrication, damaged bearings, or other problems.

4. No-load Run Test: Disconnect the motor from the load mechanically, allowing it to idle, and run the inverter, slowly increasing the frequency.

If the no-load condition is also overloaded: The problem lies with the motor, cables, or the inverter itself.

If the no-load condition is normal: The problem is on the load side or in the mechanical transmission components.

 

Step 2: In-depth investigation for normal no-load operation

If the no-load operation is normal, but overload occurs under load, it indicates that the inverter's drive capacity is sufficient, but the load is too heavy.

1. Check the mechanical transmission system:

Bearings: Check if the bearings of the motor and load machinery are lacking lubrication, damaged, or seized.

Connection mechanism: Check if the belt is too tight, slipping, or damaged; if the gearbox is lacking lubrication or worn; if the coupling is misaligned.

Guide rails/slides: Check for obstructions or insufficient lubrication.

2. Check the load itself:

Overload: For example, is the transported goods overweight or piled up; are the pump valves opened too wide, causing the flow rate to far exceed the design; are the fan dampers abnormal?

Process changes: Have the process requirements changed, causing a continuous increase in load?

3. Check the motor body:

Insulation: Use a megohmmeter to measure the insulation resistance of the motor windings to ground, checking if moisture or aging has caused a decrease in insulation, resulting in increased current.

 

Step 3: In-depth Troubleshooting for No-Load and Overload Issues

1. Inspect the Motor and Cables:

Cables: Inspect the motor power cable for damage, aging, and loose or oxidized terminals.

Motor: Measure the DC resistance of the motor windings and check for three-phase imbalance. Severe imbalance indicates an internal motor fault.

2. Check and Optimize Inverter Parameters:

Motor Parameter Self-Tuning: Accurately input the motor nameplate data into the inverter and perform static or dynamic self-tuning. This greatly improves control performance and avoids overcurrent caused by inaccurate parameters.

Acceleration/Deceleration Time: If the acceleration time is set too short, the starting current will be too high, easily leading to overload. Appropriately extend the acceleration time.

Overload Protection Factor: Check whether the motor overload protection factor or current limit value set on the inverter is reasonable.

3. Verify Inverter and Motor Selection:

Power Matching: The inverter power should be ≥ the motor power. For heavy-load starts and periodic impact loads, a higher-power inverter (one or two speed ranges) should be selected.

Current matching: Ensure that the rated output current of the frequency converter is greater than the rated current of the motor.