Instantaneous power failure (Standard models and IP55 compatible models only)
If a power failure occurs (or when power input to the inverter is shut off) for longer than 15 ms
instantaneous power failure protective function is activated to shut off the inverter output in order to prevent the
control circuit from malfunctioning. If a power failure persists for 100 ms or longer, the fault warning output is not
provided, and the inverter restarts if the start signal is ON upon power restoration. (The inverter continues
operating if an instantaneous power failure is within 15 ms
acceleration/deceleration time setting, etc.), overcurrent or other protection may be activated upon power
When instantaneous power failure protection is activated, the IPF signal is output. (Refer to
Find the cause of instantaneous power failure occurrence.
• Remedy the instantaneous power failure.
• Prepare a backup power supply for instantaneous power failure.
• Set the function of automatic restart after instantaneous power failure (Pr.57). (Refer to
10 ms for IP55 compatible models
Undervoltage (Standard models and IP55 compatible models only)
If the power supply voltage of the inverter decreases, the control circuit will not perform normal functions. In
addition, the motor torque will be insufficient and/or heat generation will increase. To prevent this, if the power
supply voltage decreases to about 150 VAC (300 VAC for the 400 V class) or below, this function shuts off the
When a jumper is not connected across P/+ and P1, the undervoltage protective function is activated.
When undervoltage protection is activated, the IPF signal is output. (Refer to
• Check if a high-capacity motor is driven.
• Check if the jumper is connected across terminals P/+ and P1.
• Check the devices on the power supply line such as the power supply itself.
• Do not remove the jumper across terminals P/+ and P1 except when connecting a DC reactor.
• If the problem still persists after taking the above measure, contact your sales representative.
Input phase loss (Standard models and IP55 compatible models only)
When Pr.872 Input phase loss protection selection is enabled ("1") and one of the three-phase power input
is lost, the inverter output is shut off. This protective function is not available when Pr.872 is set to the initial value
(Pr.872 = "0"). (Refer to
Check for a break in the cable for the three-phase power supply input.
• Wire the cables properly.
• Repair a break portion in the cable.
FR-LU08 indication Instantaneous power failure
.) In some operating status (load magnitude,
FR-LU08 indication Under Voltage
FR-LU08 indication Input phase loss
6. PROTECTIVE FUNCTIONS
6.5 Causes and corrective actions