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97
Operation when continuous operation after momentary power loss is provided , which is describing as
below :
1.
When undervoltage(UV) is detected, the inverter output is shut off and the frequency reference value
and run command given before the momentary power loss are held. Additionally, counting of the
undervoltage time starts; during counting, UV is displayed, blinking on the digital display unit and
digital operator. If undervoltage is detected, the inverter output is ahut off for the minimum baseblock
time Pn-55.
2.
After recovery from the momentary power loss, after checking that the inverter DC voltage has
recovered sufficiently, speed search operation is performed.
3. Speed search operation starts when the inverter output current exceeds the speed search operation
level Pn-54 set value. At this time, the new frequency reference value and run command are read in.
The frequency in which the inverter output current is smaller than the speed search operation level
Pn-54 set value is judged to be the speed synchronised point, and reacceleration/ redeceleration is
performed up/down to the set frequency in the set accel/decel time.
Momentary power loss occurrence
Input power supply
Recover
UV detection signal
t
B.B
Motor speed
Coasting Search Reacceleration
1. 2. 3.
* t
:Varies according to the inverter size. (Assured at 15 mS minimum.) Operation is automatically
continued if recovery from momentary power loss in t or less.
Do not provide an excessively small value for the minimum baseblock time setting. Otherwise, the
inverter protective function may operate at search operation start.(Refer to page 96.)
