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5.3.11 Instantaneous Power Failure and Speed Search
H34: IPF Restart (Factory Default: 0: Inactive Hoist
Range:0: Inactive 1: Active Traverse)
1: Active
H35: Speed Search Accel. Time (Factory Default: 2.0 sec.)
Range:0.1 - 10.0 sec.
H36: Speed Search Decel. Time (Factory Default: 2.0 sec.)
Range:0.1 - 10.0 sec.
H37: Speed Search Block Time (Factory Default: 0.0 sec.)
Range: 0.0 - 5.0 sec.
SPEED SEARCH
The Speed Search Mode is used when the drive needs to be restarted while a motor
is coasting. This function is especially important if the motor has a large load inertia.
IMPORTANT: Without speed search, restarting into a coasting motor can result in
over current in the IGBT’s.
INSTANTANEOUS POWER FAILURE (IPF)
This function is used to initiate the automatic restart mode after an IPF of over 15
msec. in duration. After the drive resets itself from an IPF it begins to search for the
current speed of the coasting motor following a time period equal to H37, Speed
Search Block Time. Once the drive determines the speed of the motor, it then
re-accelerates for a time equal to H35, Speed Search Accel. Time. The drive
decelerates for a time equal to H36, Speed Search Decel. Time, to allow the drive
output to match the decelerating motor speed. The drive then accelerates to the
previous set reference frequency. H35, H36, and H37 must be set, considering the
moment of inertia and the magnitude of torque demand of the load.
Fig. 5.3.14: IPF Function
Input Power
Motor Speed
Output Frequency
time
time
time
H37 H35 H36
Input Power Loss
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