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Application Manual CDA3000
5 Software functions
(2) Fastest possible DC-link controlled speed reduction without
limitation of ramp steepness (PFSEL = NOLIM)
(emergency stop in case of power failure)
A detected power failure is followed by a fastest possible speed reduction
regulated to the voltage reference. The voltage reference is above the
braking chopper threshold, so the energy of the motor can be discharged
by way of the braking chopper if a braking resistor is connected. When the
fixed undervoltage shutdown threshold U
ZKOff
is reached, the motor
coasts uncontrolled. When the power is restored the frequency is not
automatically increased to the preset frequency reference.
U
BCon
Braking chopper switching threshold
PO Status of power stage (active/inactive)
MU Motor uncontrolled
BR Regenerative braking
t
off
Power failure time
U
ZK
DC-link voltage
Figure 5.26 Maximum speed reduction
t
off
U
ZK
U
ZK
off
t
f/Hz
(2)
t
PFVON
PO
0
1
MU
U
BC
on
2Hz
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