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Diagnostics Optimization CT MODBUS RTU Technical Data
E300 Design Guide 465
Issue Number: 1
OHt dc bus DC bus over temperature
27
OHt DC bus trip indicates a DC bus component over temperature based on the 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 parameter
Percentage Of DC Link Thermal Trip Level (J78). If this parameter reaches 100 % then an OHt DC bus 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 power supply voltage level
• Check the AC power supply voltage balance
• Check the DC bus voltage ripple level
• Reduce motor loading
• Check the output current stability and if unstable;
• Check the motor map settings within the drive (parameters B06, B02, B07, B03, B04, B05), all modes
• Slip Compensation Enable (B10), (Open loop)
• Select fixed boost mode, parameter B09 (Open loop)
• Disconnect load and complete a rotating autotune, Motor Autotune (B11)
• Autotune the rated speed, parameter B07 (Open loop) parameter B25 (RFC-A)
• Reduce the speed loop gains, parameters I01, I02, I06 and I07 run and stop (Closed loop operation)
• Add a speed feedback filter parameter C09 (Closed loop operation)
• Add a current demand filter, parameters I05, I10 run and stop
• Check position feedback signals for noise with an oscilloscope (Closed loop operation)
• Check encoder mechanical coupling (Closed loop operation)
• Reduce duty cycle
OHt Inverter Inverter over temperature based on thermal model
21
OHt Inverter trip indicates an IGBT junction over-temperature has been detected based on the software thermal model.
Recommended actions:
• Check AC power supply input phases present and balanced
• Check DC bus ripple
• Check for motor instability
• Reduce acceleration / deceleration rates
• Reduce the maximum operating switching frequency
• Reduce motor load
• Reduce duty cycle
OHt Power Power stage over temperature
22
OHt Power trip indicates that a power stage over-temperature has been detected. From the sub-trip ‘xxyzz’, the thermistor
location is identified by ‘zz’.
OHt Power is detected at >= 90 % of the maximum threshold on starting a new travel i.e. exiting from Elevator Software
State (J03) = 0 to 1.
If during travel 100 % is reached the drive will trip immediately, where the location of the out of range temperature is
indicated by the sub-trip number as detailed in the table below:
Recommended actions:
• Check enclosure / drive fans are still functioning correctly
• Check enclosure ventilation paths, door filters
• Check correct drive size for the application, load correct
• Force heatsink cooling fans to run at maximum speed
• Increase enclosure ventilation
• Decrease acceleration / deceleration rates
• Reduce motor load
• Reduce duty cycle
• Reduce the drive switching frequency
• Use a drive with larger current / power rating
If the temperature is >= 90 % of the maximum then Global Warning (L04) = On (1) indicating that there is a thermal
issue and on the next start the elevator will trip OHt Power.
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 Inverter) trip with sub-trip 0
Source xx y zz Description
Power system 01 0 zz Thermistor location in the drive defined by zz
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