Hitachi X200-002SFE/NFU Instruction Manuals page 112

3−38
Non Stop Operation at Power OFF
Non stop operation at power OFF helps to avoid tripping or free-running of the motor
when power turns OFF during running. Inverter controls the internal DC bus voltage
by decelerating the motor, and finally makes the motor stop.
Power
DC bus voltage
Output frequency
NOTE: If the DC bus voltage comes down to the UV level during this operation, the
inverter trips with undervoltage and motor will be free-run.
NOTE: If the set value of B052<B051, then the inverter changes internally the B052 to
B051. However the displayed value is not changed.
NOTE: This function cannot be interrupted until it is completed. So if the power is
recovered during this operation, wait until the operation is done (motor stops) and then
give the run command.
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b052
b051
Undervoltage
level
When the power turns OFF during running and the internal DC bus voltage of the
inverter comes down to the set level of B051, the inverter decreases the output
frequency, which is set in B054 in a short period. (In this moment the DC bus
voltage rises thanks to the regeneration and does not go down to the UV level.)
Continues deceleration according to the set value of B053. If the DC bus voltage
rises up to the set value of B052, the inverter stop deceleration to avoid OV tripping.
In this period the DC bus voltage decreases because of no power input.
When the DC bus voltage comes down to the set value of B051, the inverter starts
deceleration according to the set value of B053 again. After this will be the
repetition from and finally comes to the motor to stop.
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