Unidrive M100-101 Quick Start Guide 39
Issue Number: 6
Et An External trip is initiated
The cause of the trip can be identified from the sub trip number 
displayed after the trip string. 
Refer to Drive User Guide.
FAN.F Fan fail Indicates the fan or fan circuitry has failed
Fi.Ch File changed A file has been changed, power cycle to clear the trip
FI.In Firmware Incompatibility The user firmware is incompatible with the power firmware.
HFxx 
trip
Hardware faults Internal drive hardware fault (see Drive User Guide)
It.Ac
Output current overload timed out 
(I
2
t)
The It.Ac trip indicates a motor thermal overload based on the 
output current and motor thermal time constant. The drive will trip 
on It.Ac when the accumulator gets to 100 %.
This can occur when:
• There is excessive mechanical load
• Ensure the load is not jammed / sticking
• Check the load on the motor has not changed
• Ensure the motor rated current is not zero
It.br
Braking resistor overload timed 
out (I
2
t)
Braking resistor overload has timed out. This can be caused by 
excessive braking resistor energy.
no.PS No power board No communication between the power and control boards.
O.Ld1 Digital output overload
The total current drawn from 24 V user supply or from the digital 
output has exceeded the limit.
O.SPd
Motor frequency has exceeded 
the over frequency threshold
Excessive motor speed (typically caused by mechanical load 
driving the motor).
Oh.br Braking IGBT over-temperature Braking IGBT over-temperature.Detected by thermal model
Oh.dc DC bus over temperature
DC bus component over temperature based on a software 
thermal model. 
Oht.C Control stage over-temperature Control stage over-temperature detected.
Oht.I
Inverter over temperature based 
on thermal model
IGBT junction over-temperature has been detected based on a 
software thermal model.
Oht.P Power stage over temperature
This trip indicates that a power stage over-temperature has been 
detected. 
Oht.r Rectifier over temperature
The Oht.r trip indicates that a rectifier over-temperature has been 
detected. 
OI.A1 Analog input 1 over-current Current input on analog input 1 exceeds 24 mA.
OI.AC
Instantaneous output over current 
detected
The instantaneous drive output current has exceeded.The set 
limit. 
Possible solutions:
• Increase acceleration/deceleration rate
• If seen during autotune reduce the voltage boost
• Check for short circuit on the output cabling
• Check integrity of the motor insulation using an insulation 
tester
• Is the motor cable length within limits for the frame size
• Reduce the values in the current loop gain parameters
OI.br
Braking IGBT over current 
detected: short circuit protection 
for the braking IGBT activated
Over current has been detected in braking IGBT or braking IGBT 
protection has been activated.
Possible cause:
• Check brake resistor wiring
• Check braking resistor value is greater than or equal to the 
minimum resistance value
• Check braking resistor insulation
Trip 
code
Condition Description
Sub-trip Reason
1 External Trip  = 1
Unidrive M100 101 Quick Start Guide English Iss6.book  Page 39  Wednesday, September 9, 2015  4:07 PM