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Chapter 4
Description of Operation
4-4
Overtemperature
The drive contains a thermal switch on the heat sink which indirectly
senses transistor module temperature. If the temperature rating of the
switch is exceeded, the DROK contact opens and the drive is disabled.
Power Fault
A fault related to the power bridge section of the drive will cause the drive
to be disabled and open the DROK contact.
Control Voltage Fault
If the control voltage varies more than 10% of the nominal 12V DC, this
fault will occur. When a fault is detected, the DROK contact opens and the
drive is disabled.
Resolver Loss Fault
If the resolver wiring is grounded or missing, this fault will occur. When a
fault is detected, the DROK contact opens and the drive is disabled.
Overvoltage
The DC power bus voltage is continuously monitored. If it exceeds a preset
level of 405V DC, the DROK contact opens and the drive is disabled
Undervoltage
If the DC power bus voltage drops below 50% of its nominal operating
value an undervoltage fault occurs. Parameter 130 selects the reaction of
the DROK contacts to an undervoltage detection. Two options are possible:
1) DROK opens, but closes when the bus voltage is restored; 2) DROK is
not affected by an undervoltage.
Important: Regardless of interaction with the DROK contacts, the
transistor bridge is disabled upon an undervoltage condition. This is done
to protect the output transistors against voltage transients.
Current Foldback
The drive contains a fixed time versus current overload circuit which
monitors the current through each leg of the output bridge. If the overload
is sustained for a period, resulting in the drive rating being exceeded, the
circuitry will reduce (foldback) the peak output current of the drive. A
continuous overload will fold the available peak current down to its
continuous rating. This condition will reduce the current limit or torque
available to the motor.
Enable LED
The application of an enable signal by the machine position drive will
cause the front panel ENABLE LED to illuminate.
Status LED
The status of the power supplies and fault conditions are monitored
continuously. If a fault is present, the front panel FAULT/DRIVE READY
LED will flash red and the DROK contact will be open. If the drive is
operational, this LED will be green.
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