Hitachi WJ C1 Series User Manual

Chapter 9 Inverter Functions
9-9-9
9.9.6 Restarting after Instantaneous Power Failure/Undervoltage
 How to keep the inverter running even if the main power is momentarily lost due to a power
failure?
 After an undervoltage error occurs, how to restart the inverter at an output frequency that
corresponds to the motor speed?
 When the power supply falls below the undervoltage level and then power is restored, the
inverter can be set to trip or restart without tripping using "Restart mode selection after
instantaneous power failure/undervoltage error [b001]".
 When restart ([b001] = 01 to 04) is selected, the restart operation is repeated the number of
times specified in "Number of retries after instantaneous power failure/undervoltage [b005]",
and then the inverter trips after the specified reties are finished. (Only when "Unlimited (01)" is
selected for [b005], unlimited restarts are enabled.)
 When frequency matching restart is performed ([b001] = 02, 03), the restart mode is active
frequency matching restart at the frequency of the previous output interruption. For details,
refer to "9.7.3 Starting with Frequency Matching".
 To perform an active frequency matching restart ([b001] = 04), refer to "9.7.4 Starting with
Active Frequency Matching" for details.
 When power is turned off to save energy, etc. while the inverter is stopped, undervoltage trips
during stop can be avoided by setting "Enable instantaneous power failure/undervoltage error
while in stop status [b004]" to "Disable (00)" or "Disable at Stop/Decel. stop (02)".
 "DC bus voltage monitor [d102]" can be used to monitor the P-N voltage in the inverter.
 If the power failure lasts for long time and the control microcomputer is completely shut down,
after power is restored, the same procedure will be followed as when the power is turned on.
 When the P-N voltage falls to or below the undervoltage level (approx. 172.5 VDC for 200 V
class and 345 VDC for 400 V class), the inverter shuts off the output and the motor runs free.
When the time until power returns is defined as "Undervoltage time", an "Undervoltage error
[E09]" will occur in the following cases.
- When [b001] = "Trip (00)" and the undervoltage time ≦ "Instantaneous power failure/
undervoltage allowed time [b002]".
- When [b001] ≠ "Trip (00)" and the undervoltage time > "Instantaneous power failure/
undervoltage allowed time [b002]".
- If the undervoltage time is equal to or longer than about 40 seconds, an "Undervoltage error
[E09]" occurs without waiting for power to return.
 When "Decelerate and stop with frequency matching and then trip (03)" is specified and an
overvoltage or overcurrent error occurs during deceleration after restart function is performed,
an "Undervoltage error [E09]" appears and the motor runs free. In this case, increase the
deceleration time.
 The "Undervoltage [UV]" signal is output when the voltage is insufficient regardless of whether a
trip occurs or not. This signal continues to output while the inverter's control circuit power
remains (including external 24 VDC power supply).
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Hitachi WJ C1 Series Specifications

General

Brand	Hitachi
Model	WJ C1 Series
Category	Inverter
Language	English