OL3 fault in an INVT GD10 drive indicates an Electrical Overload Pre-Alarm. This means the inverter's output current has approached a pre-set overload threshold, but hasn't yet exceeded it. This is often a precursor to a full-blown overload (OL1 or OL2) if the condition persists.

Common Causes of OL3 Faults:

1. Mechanical Overload:

   • Excessive Load: The motor may be subjected to a load that is nearing its rated capacity.
   • Mechanical Issues: Mechanical problems like bearing wear, belt slippage, or pump blockages can increase the motor's load.

2. Electrical Overload:

   • Voltage Fluctuations: Variations in the supply voltage can lead to increased motor current draw.
   • Short Circuits: Internal or external short circuits can cause excessive current flow.
   • Incorrect Motor Sizing: The motor may be undersized for the application.

3. Inverter Settings:

   • Incorrect Current Limit: The inverter's current limit may be set too low, causing frequent pre-alarm conditions.
   • Motor Parameter Mismatch: Incorrect motor parameters can lead to inaccurate current calculations.

Troubleshooting Steps:

1. Check the Mechanical Load:

   • Inspect the driven equipment for any signs of mechanical issues.
   • Ensure the load is within the motor's rated capacity.

2. Verify Electrical Connections:

   • Check for loose or damaged connections in the motor and inverter wiring.
   • Inspect the motor windings for signs of damage or overheating.

3. Inspect the Inverter:

   • Verify the inverter's current limit setting and adjust it if necessary.
   • Ensure the motor parameters are correctly configured in the inverter.

4. Monitor Motor Temperature:

   • Use a thermal imaging camera or a contact thermometer to measure the motor's temperature.
   • Excessive temperature can indicate an impending overload.