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128 Unidrive M100 User Guide
Issue Number: 1
Oh.br Braking IGBT over-temperature
101
The Oh.br over-temperature trip indicates that braking IGBT over-temperature has been detected based on software
thermal model.
Recommended actions:
• Check braking resistor value is greater than or equal to the minimum resistance value
Oh.dc DC bus over temperature
27
The Oh.dc trip indicates a DC bus component over temperature based on a software thermal model. The drive includes a
thermal protection system to protect the DC bus components within the drive. This includes the effects of the output current
and DC bus ripple. The estimated temperature is displayed as a percentage of the trip level in Pr 07.035. If this parameter
reaches 100 % then an Oh.dc trip is initiated. The drive will attempt to stop the motor before tripping. If the motor does not
stop in 10 seconds the drive trips immediately.
Recommended actions:
• Check the AC supply voltage balance and levels
• Check DC bus ripple level
• Reduce duty cycle
• Reduce motor load
• Check the output current stability. If unstable;
Check the motor map settings with motor nameplate (Pr 05.006, Pr 05.007, Pr 05.008, Pr 05.009, Pr 05.010,
Pr 05.011)
Disable slip compensation (Pr 05.027 = 0)
Disable dynamic V to F operation (Pr 05.013 = 0)
Select fixed boost (Pr 05.014 = Fixed)
Select high stability space vector modulation (Pr 05.020 = 1)
Disconnect the load and complete a rotating autotune (Pr 05.012)
Oht.C Control stage over-temperature
219
This trip indicates that a control stage over-temperature has been detected if Cooling Fan control (06.045) = 0.
Recommended actions:
Increase ventilation by setting Cooling Fan control (06.045) > 0
Oht.I Inverter over temperature based on thermal model
21
This trip indicates that an IGBT junction over-temperature has been detected based on a software thermal model.
Recommended actions:
• Reduce the selected drive switching frequency
• Ensure Auto-switching Frequency Change Disable (05.035) is set to OFF
• Reduce duty cycle
• Increase acceleration / deceleration rates
• Reduce motor load
• Check DC bus ripple
• Ensure all three input phases are present and balanced
Trip Diagnosis
Source xx y zz Description
Control system 00 2 00 DC bus thermal model gives trip with sub-trip 0
Source xx y zz Description
Control system 00 1 00 Inverter thermal model gives {Oht.I} trip with sub-trip 0