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32 BD SERVO DRIVES USER GUIDE
Protection Circuits
The BD Drive has a number of protection circuits which automatically prevent damage ocurring
during fault conditions. If a fault does occur it will cause a front panel LED to light up and may
de-energise the drive.
The front panel LED indicators are described below.
IT Foldback
If the IT foldback yellow LED comes on, it means the drive has been required to deliver too much
current for too long a time period. In this situation the drive will automatically reduce the motor
current to below 60% of the peak current.
IT foldback will occur if the drive is required to deliver its full output current for more than 5ms at
a speed of less than 6rps. The full current limit will be restored as soon as the conditions
causing IT foldback have been removed.
Current limit
The yellow I limit LED indicates that the current demand is exceeding the drives maximum
current capability. Note: The motor current level can be adjusted using bit switches 7 and 8.
Drive Fault
The red drive fault LED can indicate one of the following faults:
• Overvoltage
• Undervoltage
• Supply failure
• Overcurrent
• Overspeed
An overvoltage condition may be caused by:
• Excessive AC power input voltage
• A fault in the dump circuit
• The application requires a larger dump capacity
An under voltage condition may occur if the AC input power voltage drops when the maximum
drive power is drawn from the supply i.e. poor AC supply regulation.
A supply failure may indicate a short circuit exists in the encoder or other external wiring, or it
could be due to a fault in the internal power supply. If the fault is still being indicated when all
external wiring is disconnected, the drive is probably faulty.
An overcurrent fault, indicated by the illumination of the drive fault LED and the red overcurrent
LED mounted within the case, can be caused by a shorted motor winding or a drive fault. If the
fault is still indicated when the motor is unplugged, the drive may be faulty.
An overspeed fault means that the motor has exceeded the factory-set overspeed threshold. If
your application requires very high speed performance, please contact Digiplan for advice.
Overtemperature