ABB ACS880 Series, Firmware Manual

Page: 118 / 764

Settings and diagnostics
Parameter group: 44 Mechanical brake control (page 441) .
Events: 71A2 Mech brake closing failed (page 667) , 71A3 Mech brake opening
failed (page 667) , 71A5 Mech brk opening not allowed (page 667) and A7A1 Mechanical
brake closing failed (page 683) .
DC voltage control
￭ Overvoltage control
Overvoltage control of the intermediate DC link is typically needed when the motor
is in generating mode. The motor can generate when it decelerates or when the
load overhauls the motor shaft, causing the shaft to turn faster than the applied
speed or frequency. To prevent the DC voltage from exceeding the overvoltage
control limit, the overvoltage controller automatically decreases the generating
torque when the limit is reached. The overvoltage controller also increases any
programmed deceleration times if the limit is reached; to achieve shorter
deceleration times, a brake chopper and resistor may be required.
￭
Undervoltage control (power loss ride-through)
If the incoming supply voltage is cut off, the drive will continue to operate by
utilizing the kinetic energy of the rotating motor. The drive will be fully operational
as long as the motor rotates and generates energy to the drive. The drive can
continue operation after the break if the main contactor (if present) remained
closed.
Note: Units equipped with a main contactor must be equipped with a hold circuit
(e.g. UPS) to keep the contactor control circuit closed during a short supply break.
118 Program features