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Application Manual CDA3000
5 Software functions
Note: The power failure bridging selector presets the parameters of
the subject area to values for max. DC-link buffering or fastest
possible speed reduction. We therefore recommend not
changing the parameter setting.
Power failure detection
The power failure is detected based on the measured DC-link voltage
(U
ZK
) when a parameterizable lower limit voltage threshold (PFVON) is
infringed.
PFVON DC-link switching threshold as from which power failure bridging is
activated
t
off
Time of power failure
Figure 5.23 Power failure voltage threshold
Explanatory notes
• When “fastest possible DC-link controlled speed reduction” is set
with 340-PFSEL=NOLIM and “longest possible DC-link buffering
without restart is set with 340-PFSEL=RETRN, no check is made
for restoration of mains power.
• If the DC-link control reference (342-PFVRF) is above the DC-link
switching threshold above which power failure bridging is activated
(341 -PFVON), the power failure bridging function jumps between
“on” and “off”. When “... with restart” is set, this results in a switch
between deceleration and acceleration ramp.
U
ZK
t
t
off
PFVON
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