Allen-Bradley PowerFlex 70 User Manual page 10

P-4 Overview
ATTENTION: Nuisance tripping may occur in firmware version
1.011 and earlier due to unstable currents. When using a motor that is
!
connected for a voltage that is different from the drive (e.g., using a
230V connected motor with a 460V drive) the following adjustment
must be made to "Stability Gain" using DriveExplorer software and a
personal computer.
Motor Nameplate Voltage
-------------------------------------------------------------- -
Drive Rated Voltage
Any adjustment made to "Stability Gain" must be manually restored if
the drive is reset to defaults or is replaced.
If unstable currents are still present after making the adjustment,
contact the factory for assistance.
ATTENTION: The "adjust freq" portion of the bus regulator function
is extremely useful for preventing nuisance overvoltage faults resulting
!
from aggressive decelerations, overhauling loads, and eccentric loads.
It forces the output frequency to be greater than commanded frequency
while the drive's bus voltage is increasing towards levels that would
otherwise cause a fault; however, it can also cause either of the
following two conditions to occur.
1. Fast positive changes in input voltage (more than a 10% increase
within 6 minutes) can cause uncommanded positive speed changes;
however an "OverSpeed Limit" fault will occur if the speed reaches
[Max Speed] + [Overspeed Limit]. If this condition is unacceptable,
action should be taken to 1) limit supply voltages within the
specification of the drive and, 2) limit fast positive input voltage
changes to less than 10%. Without taking such actions, if this operation
is unacceptable, the "adjust freq" portion of the bus regulator function
must be disabled (see parameters 161 and 162).
2. Actual deceleration times can be longer than commanded
deceleration times; however, a "Decel Inhibit" fault is generated if the
drive stops decelerating altogether. If this condition is unacceptable, the
"adjust freq" portion of the bus regulator must be disabled (see
parameters 161 and 162). In addition, installing a properly sized
dynamic brake resistor will provide equal or better performance in most
cases.
Note: These faults are not instantaneous and have shown test results
that take between 2 and 12 seconds to occur.
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