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Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
*1
Resetting the converter unit initializes the internal cumulative heat value of the electronic thermal relay function.
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
146
6. PROTECTIVE FUNCTIONS
6.5 Causes and corrective actions
E.OVT
Overvoltage trip
If the converter unit's internal main circuit DC voltage reaches or exceeds the specified value, the protection
circuit is activated to stop the outputs of the inverter. The overvoltage trip protection function may also be
activated by a surge voltage produced in the power supply system or an input phase loss.
• Check for sudden load change and excessive regeneration.
• Check that any power supply failure did not occur.
• Keep the load stable.
• Check the power supply.
E.THC
Converter overload trip (electronic thermal relay function)
For the protection of converter unit diode, the electronic thermal O/L relay is activated in inverse-time
characteristics against the converter unit input current to shut off the inverter output.
• Check the motor for the use under overload.
• Check that the capacity of the inverter used is not larger than that of the converter unit.
• Reduce the load.
• Check the configuration of the inverter and the converter unit again.
E.FIN
Heat sink overheat
When the heat sink overheats, the temperature sensor is activated, and the inverter output is stopped.
The FIN signal can be output when the temperature becomes approximately 85% of the heat sink overheat
protection operation temperature.
For the terminal used for the FIN signal output, assign the function by setting "26" (positive logic) or "126"
(negative logic) in any parameter from Pr.190 to Pr.195 (Output terminal function selection). (Refer to
90.)
• Check for too high surrounding air temperature.
• Check for heat sink clogging.
• Check that the cooling fan is not stopped. (Check that FN is not displayed on the operation panel.)
• Set the surrounding air temperature to within the specifications.
• Clean the heat sink.
• Replace the cooling fan.
E.IPF
Instantaneous power failure
If a power failure (converter unit input shut-off) occurs and lasts for longer than 5 ms, the 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 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 5 ms.)
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
E.UVT
Undervoltage
If the power supply voltage of the converter unit 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, the output
of the inverter is stopped when the power supply voltage drops to about 440 VAC or lower. The undervoltage
protection function may also be activated by an input phase loss.
When undervoltage protection is activated, the IPF signal is output. (Refer to
Check if a high-capacity motor is driven.
• Check the devices on the power supply line such as the power supply itself.
• If the problem still persists after taking the above measure, contact your sales representative.
*1
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