Rockwell Automation 1336VT AC DRIVE 5-300AMP (2-160KW) PROGRAMMING MANUAL - Manual (Page 23)

Local and Serial Port Parameters
Firmware Version 1.01-3.01
Chapter 3
3-9
Parameter 11 Ċ Decel Frequency
Hold
Freq P R
P R Enter Off/On
0
1
0
Read and Write
Units
Minimum Value
Maximum Value
Factory Setting
This parameter may be used to guard against overvoltage fault trips from
occurring due to fast decel ramps. The status of this parameter selects the
drive response to a condition where the DC bus level is rising towards the
overvoltage trip point.
With Decel Frequency Hold set to 0, drive logic continues to follow the
decel ramp. If the bus voltage rises to 810V DC however, the drive will trip
a bus overvoltage fault (F05).
With Decel Frequency Hold set to 1, the drive logic will not follow the
programmed decel ramp if the bus voltage rises above 110% of nominal
bus voltage. Typically a rise in bus voltage is the result of decelerating at a
fast rate. This causes the connected motor to regenerate energy back to the
DC bus faster than the drive/motor can dissipate the energy. With the decel
ramp inhibited, the regenerated energy will reduce and stop increasing the
DC bus voltage. As the amount of regenerated energy decreases, the DC
bus voltage decreases to below 110% of nominal bus voltage and allows
the drive logic to continue its original decel ramp.