MITSUBISHI ELECTRIC FR-S520 - Manual (Page 148)

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Operation Panel Indication OV3 FR-PU04 OV During Dec
Name Regenerative overvoltage cut-off during deceleration or stop
Description
When the main circuit DC voltage in the inverter rises to or above
the specified value due to excessive regenerative energy during
deceleration or stop, the protective circuit is activated to stop the
inverter output. The circuit may also be activated by a surge
voltage produced 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 inertia moment of the load)
Decrease the braking duty.
Install a power factor improving reactor.
Operation Panel Indication THM FR-PU04 Motor Overload
Name
Motor overload cut-off (electronic thermal overcurrent protection)
(* 1)
Description
The electronic overcurrent protection in the inverter detects motor
overheat due to overload or reduced cooling capability during low-
speed operation to stop the inverter output. When a multi-pole
motor or two or more motors are run, provide a thermal relay in
the output side of the inverter.
Protection from burning due to motor temperature rise
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 THT FR-PU04 Inv. Overload
Name
Inverter overload cut-off (electronic thermal overcurrent protection)
(* 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 overcurrent protection to
be activated to stop the inverter output in order to protect the
output transistors.
Output transistor protection from overheat
Check point Check the motor for use under overload.
Corrective action Reduce the load weight.
*1. Resetting the inverter initializes the internal heat integrating data of the
electronic overcurrent protection.
Operation Panel Indication FIN FR-PU04 H/Sink O/Temp
Name Fin overheat
Description
If the cooling fin overheats, the overheat sensor is actuated to
stop the inverter output.
Check point
Check for too high ambient temperature.
Check for cooling fin clogging.
Corrective action Set the ambient temperature to within the specifications.