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78
Firmware description
3ADW000379R0501 DCS550 Manual e e
Dynamic braking
General
Dynamic braking can stop the drive. The principle is to transfer the power of the machine inertia into a braking
resistor. Therefore, the armature circuit has to be switched over from the drive to a braking resistor.
Additionally flux and field current have to be maintained.
Operation
Activation
Dynamic breaking can be activated by all stop modes, in cases of a fault or due to communication breaks:
−
Off1Mode (21.02) when UsedMCW (7.04) bit 0 On is set to low,
−
StopMode (21.03) when UsedMCW (7.04) bit 3 Run is set to low,
−
E StopMode (21.04) when UsedMCW (7.04) bit 2 Off3N is set to low,
−
FaultStopMode (30.30) in case of a trip level 4 fault,
−
SpeedFbFltMode (30.36) in case of a trip level 3 fault,
−
LocalLossCtrl (30.27) when local control is lost,
−
ComLossCtrl (30.28) when communication is lost,
In addition dynamic braking can be forced by setting AuxCtrlWord (7.02) bit 5 to high. At the same time,
UsedMCW (7.04) bit 3 Run must be set to low.
Application example of dynamic breaking
Function
During dynamic braking the field current is maintained by keeping the field exciter activated. The integrated
field exciter will be supplied via the main contactor, thus CurCtrlStat1 (6.03) bit 7 stays high
(MainContactorOn) until zero speed is reached.
①
The activation of dynamic braking immediately sets CurCtrlStat1 (6.03) bit 6 to high (dynamic braking
active).
②
Dynamic braking forces the armature current to zero and opens the DC-breaker by setting CurCtrlStat1
(6.03) bit 14 to high (Trip DC-breaker).
③
After the armature current is zero and the DC-breaker acknowledge is gone CurCtrlStat1 (6.03) bit 8 is set
to high (DynamicBrakingOn). Connect this signal to a digital output (see group 14) and used it to close
the brake contactor. As soon as the brake contactor is closed, dynamic braking starts and decreases the
speed.
④
With DynBrakeAck (10.22) it is possible to select a digital input for the brake resistor acknowledge. This
input sets A105 DynBrakeAck [AlarmWord1 (9.06) bit 4] as long as the acknowledge is present. Thus the
drive cannot be started or re-started while dynamic braking is active.
Summary of Contents for DCS550 Series
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