Instruction manual

166
PROTECTIVE FUNCTIONS
I
Note:1. Resetting the inverter initializes the internal heat integrating data of the
electronic thermal relay function.
Operation Panel Indication E. OV3 FR-PU04-MGI OV During Dec
Name Regenerative overvoltage shut-off during deceleration or stop
Description
If regenerative energy causes the inverter's internal main
circuit DC voltage to reach or exceed the specified value, the
protective circuit is activated to stop the inverter output.
It may also be activated by a surge voltage generated in the
power supply system.
Check point Check for sudden speed reduction.
Corrective action
• Increase the deceleration time. (Set the deceleration time
which matches the moment of inertia of the load)
• Decrease the braking duty.
Operation Panel Indication E. THM FR-PU04-MGI Motor Overload
Name
Motor overload shut-off (electronic thermal relay function)
(Note 1)
Description
The electronic overcurrent protection in the inverter detects
motor overheat due to overload or reduced cooling capability
during constant-speed operation to stop the inverter output.
When a multi-pole motor or two or more motors are run,
provide a thermal relay on the output side of the inverter.
Check point Check the motor for use under overload.
Corrective action
• Reduce the load weight.
• For the constant-torque motor, change the Pr. 71 setting to
the constant-torque motor setting.
Operation Panel Indication E. THT FR-PU04-MGI Inv. Overload
Name
Inverter overload shut-off (electronic thermal relay function)
(Note 1)
Description
If a current of more than 150% of the rated output current flows
and overcurrent shut-off does not occur (200% or less),
inverse-time characteristics cause the electronic thermal relay
function to be activated to stop the inverter output in order to
protect the output transistors.
Check point Check the motor for use under overload.
Corrective action Reduce the load weight.
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