Motor Overheat Alarm (Level 3)

What does OH3 mean?

This alarm indicates that the motor's temperature, as monitored by an analog input (H3-09=E), has exceeded the OH3 alarm threshold (1.17V). It serves as an early warning of potential motor overheating, allowing for intervention before a more critical fault occurs that could lead to a drive stop.

• Motor operating under sustained heavy load, causing its internal temperature to rise above normal limits.
• Inadequate motor cooling due to blocked motor fan, dirty motor fins, or high ambient temperature around the motor.
• Motor winding insulation degradation leading to localized hot spots within the motor.
• Incorrect scaling or wiring of the analog temperature sensor (e.g., PTC, NTC, RTD) connected to input H3-09.
• High drive output current due to mis-tuned motor parameters (e.g., E1-01) or excessive motor slip.

Click steps to track your progress.

1. 1

   1. Verify the analog input signal at terminal H3-09 is correctly wired and scaled, measuring the voltage during motor operation.

2. 2

   2. Measure the motor surface temperature using an infrared thermometer and compare it to the motor's rated operating temperature.

3. 3

   3. Inspect the motor's cooling fan for proper operation and ensure cooling fins are free of debris and obstructions.

4. 4

   4. Reduce the mechanical load on the motor if it is consistently running at high current, causing thermal stress.

5. 5

   5. Check for any phase current imbalance at the drive output (U, V, W terminals) that could indicate internal motor issues.