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Unidrive M702 User Guide 263
Issue Number: 3
OHt Rectifier Rectifier over temperature
102
The OHt Rectifier indicates that a rectifier over-temperature has been detected. The thermistor location can be identified
from the sub-trip number.
Recommend actions:
• Check the motor and motor cable insulation with an insulation tester
• Fit an output line reactor or sinusoidal filter
• Force the heatsink fans to run at maximum speeds by setting Pr 06.045 = 11
• Check enclosure / drive fans are still functioning correctly
• Check enclosure ventilation paths
• Check enclosure door filters
• Increase ventilation
• Decrease acceleration / deceleration rates
• Reduce duty cycle
• Reduce motor load
OI ac Instantaneous output over current detected
3
The instantaneous drive output current has exceeded above VM_DRIVE_CURRENT_MAX.
Recommended actions:
• Acceleration/deceleration rate is too short
• If seen during auto-tune reduce the voltage boost
• Check for short circuit on the output cabling
• Check integrity of the motor insulation using an insulation tester
• Check feedback device wiring
• Check feedback device mechanical coupling
• Check feedback signals are free from noise
• Is motor cable length within limits for the frame size
• Reduce the values in the speed loop gain parameters - (Pr 03.010, 03.011, 03.012) or (Pr 03.013, 03.014, 03.015)
• Has the phase angle autotune been completed? (RFC-S mode only)
• Reduce the values in current loop gain parameters (RFC-A, RFC-S modes only)
OI Brake Braking IGBT over current detected: short circuit protection for the braking IGBT activated
4
The OI Brake trip indicates that over current has been detected in braking IGBT or braking IGBT protection has been
activated.
Recommended actions:
• Check brake resistor wiring
• Check braking resistor value is greater than or equal to the minimum resistance value
• Check braking resistor insulation
OI dc Power module over current detected from IGBT on state voltage monitoring
109
The OI dc trip indicates that the short circuit protection for the drive output stage has been activated.
Recommended actions:
• Disconnect the motor cable at the drive end and check the motor and cable insulation with an insulation tester
• Replace the drive
Trip Diagnosis
Source xx y zz Description
Power
system
Power module
number
Rectifier
number
zz Thermistor location defined by zz
Source xx y zz Description
Control
system
00
Rectifier
number
00
Instantaneous over-current trip when the measured AC current
exceeds VM_DRIVE_CURRENT[MAX].
Power
system
Power
module
number
0
Source xx y zz Description
Power
system
Power
module
number
0 00 Braking IGBT instantaneous over-current trip