Causes and corrective actions
PROTECTIVE FUNCTIONS
655
6 5
Operation panel
indication
E.UVT FR-PU07 Under Voltage
Name
Undervoltage (Standard models and IP55 compatible models only)
Description
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
inverter output.
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 page 528, page 534.)
Check point
• Check if a high-capacity motor is driven.
• Check if the jumper is connected across terminals P/+ and P1.
Corrective action
• Check the power supply system equipment such as the power supply.
• 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.
Operation panel
indication
E.ILF FR-PU07 Input phase loss
Name
Input phase loss (Standard models and IP55 compatible models only)
Description
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 page 342)
Check point
Check for a break in the cable for the three-phase power supply input.
Corrective action
• Wire the cables properly.
• Repair a break portion in the cable.
Operation panel
indication
E.OLT FR-PU07 Stll Prev STP
Name
Stall prevention stop
Description
If the output frequency has fallen to 0.5 Hz by stall prevention operation and remains for 3 s, a fault (E.OLT)
appears and the inverter trips. OL appears while stall prevention is being activated.
When speed control is performed, a fault (E.OLT) appears and the inverter trips if frequency drops to the
Pr.865 Low speed detection (initial value is 1.5 Hz) setting by torque limit operation and the output torque
exceeds the Pr.874 OLT level setting (initial value is 150%) setting and remains 3 s.
Check point
• Check the motor for the use under overload.
• Check that the Pr.865 and Pr.874 values are correct.
(Check the Pr.22 Stall prevention operation level setting under V/F control and Advanced magnetic flux
vector control.)
• Check if a motor is connected under PM sensorless vector control.
Corrective action
• Reduce the load.
• Change the Pr.22, Pr.865, and Pr.874 values. (Check the Pr.22 setting under V/F control and Advanced
magnetic flux vector control.)
• For a test run without connecting a motor, select the PM sensorless vector control test operation.(Refer to
page 166.)
• Also check that the stall prevention (overcurrent) warning (OL) or the stall prevention (overvoltage) warning
(oL) countermeasure is taken.
V/F
V/F
Magnetic flux
Magnetic flux
Sensorless
Sensorless
Vector
Vector
PM
PM
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