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Operation panel
indication
Stall prevention (overvoltage)
Name
• When the output voltage of the inverter increases, the stall prevention (overvoltage) function is activated.
• The regeneration avoidance function is activated due to excessive regenerative power of the motor. (Refer to
page
199.)
• The following section explains the stall prevention (overvoltage) function.
Description
During deceleration
• Check for sudden speed reduction.
Check point
• Check if the regeneration avoidance function (Pr.882, Pr.883, Pr.885, Pr.886) is enabled. (Refer to
Corrective action
The deceleration time may change. Increase the deceleration time using Pr.8 Deceleration time.
Operation panel
indication
Electronic thermal O/L relay pre-alarm
Name
Appears if the cumulative value of the electronic thermal O/L relay reaches or exceeds 85% of the preset level
Description
of Pr.9 Electronic thermal O/L relay. If the value reaches 100% of Pr.9 setting, motor overload trip (electronic
thermal O/L relay) (E.THM) occurs.
• Check for large load or sudden acceleration.
Check point
• Check that the Pr.9 setting is appropriate. (Refer to
• Reduce the load and frequency of operation.
Corrective action
• Set an appropriate value in Pr.9. (Refer to
Operation panel
indication
PU stop
Name
• The motor is stopped using
the mode other than the PU operation mode, set Pr.75 Reset selection/disconnected PU detection/PU stop
Description
selection. Refer to
• The motor is stopped by the emergency stop function.
Check point
• Check if the motor is stopped by pressing
• Turn OFF the start signal and switch the operation mode to the PU operation mode.
Corrective action
Operation panel
indication
Undervoltage
Name
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
Description
supply voltage decreases to about 115 VAC (230 VAC for the 400 V class) or below, this function shuts off the
inverter output.
• Check that the power supply voltage is appropriate.
Check point
• Check if a high-capacity motor is driven.
Investigate the devices on the power supply line such as the power supply itself.
Corrective action
Operation panel
indication
Inrush current limit resistor overheat
Name
The inrush current limit resistor is a PTC thermistor. Resistance of the PTC thermistor is increased when power
ON/OFF is repeated. When the resistance is increased, a huge gap between the peak voltage and the bus
Description
voltage is generated and the gap may cause a large inrush current flow. The surge voltage causes overvoltage
error and the inverter displays a warning indication.
• Check that power ON/OFF is not repeated frequently.
Check point
• Check that the inrush current limit circuit is not damaged.
Configure a circuit where frequent power ON/OFF is not repeated.
Corrective action
If the problem still persists after taking the above measure, contact your sales representative.
OLV
If the regenerative power of the motor exceeds the regenerative power consumption
capability, this function stops decreasing the frequency to prevent overvoltage trip. As
soon as the regenerative power has reduced, deceleration resumes.
TH
PS
under the mode other than the PU operation mode. (To enable
page 85
for details.)
UV
IH
FR-LU08 indication
oL
FR-LU08 indication
TH
page
112.)
page
112.)
FR-LU08 indication
PS
on the operation panel.
—
FR-LU08 indication
―
FR-LU08 indication
6.5 Causes and corrective actions
page
199.)
under
6. PROTECTIVE FUNCTIONS
1
2
3
5
6
7
8
9
10
213
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