2-134 Power Loss
The inverter output is disabled and the motor coasts if the output frequency
drops to zero or if the bus voltage drops below Vopen or if any of the “run
permit” inputs are de-energized.
The pre-charge relay opens if the bus voltage drops below Vopen.
The pre-charge relay closes if the bus voltage rises above Vclose
If the bus voltage rises above Vrecover for 20mS, the drive determines the
power loss is over. The power loss alarm is cleared.
If the drive is still in inertia ride through operation, the drive immediately
accelerates at the programmed rate to the set speed. If the drive is coasting
and it is in a “run permit” state, the reconnect algorithm is run to match the
speed of the motor. The drive then accelerates at the programmed rate to the
set speed.
Half Voltage
This mode provides the maximum power ride through. In a typical
application 230VAC motors are used with a 480VAC drive, the input
voltage can then drop to half and the drive is still able to supply full power
to the motor.
The drive determines a power loss has occurred if the bus voltage drops
below Vtrigger.
If the drive is running the inverter output is disabled and the motor coasts.
If the bus voltage drops below Vopen/Vmin (In this mode of operation
Vopen and Vmin are the same value) or if the Enable input is de-energized,
the inverter output is disabled and the motor coasts. If the Not Stop or Run
inputs are de-energized, the drive stops in the programmed manner.
680V
620V
560V
500V
305V
407V
Bus Voltage
Motor Speed
Output Enable
Power Loss
Pre-Charge
Drive Fault
480V example shown, see Table 2.Z for further information.
!
ATTENTION: To guard against drive damage, a minimum line
impedance must be provided to limit inrush current when the
power line recovers. The input impedance should be equal or
greater than the equivalent of a 5% transformer with a VA rating
6 times the drive’s input VA rating.
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