Settings and diagnostics
Parameter group: 44 Mechanical brake control (page 395).
Events: 71A2 Mech brake closing failed (page 554), 71A3 Mech brake opening
failed (page 554), 71A5 Mech brk opening not allowed (page 555) and A7A1 Mechanical
brake closing failed (page 570).
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.
Program features 81
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