Filter
Top Products
PROTECTIVE FUNCTIONS
165
Operation Panel
Indication
E.THM
FR-PU04
Motor Overload
Name
Motor overload shut-off (electronic overcurrent protection) (Note 1)
Description
The electronic overcurrent protection in the inverter detects motor overheat due
to overload or reduced cooling capability during constant-speed operation.
When 85% of the preset value is reached, pre-alarm (TH indication) occurs.
When the specified value is reached, the protective circuit is activated to stop
the inverter output. When a special motor such as a multi-pole motor or two or
more motors are run, provide a thermal relay in the inverter output side since
the motor(s) cannot be protected by the electronic overcurrent protection.
Check point
Check the motor for use under overload.
Corrective action
•
Reduce the load weight.
•
For a constant-torque motor, change the Pr. 71 setting to the constant-torque
motor setting.
Operation Panel
Indication
E.THT
FR-PU04
Inv. Overload
Name
Inverter overload shut-off (electronic overcurrent protection) (Note 1)
Description
If a current of more than 120% of the rated output current flows and overcurrent
shut-off does not occur (150% 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.
(Overload immunity 120%, 60s.)
Check point
Check the motor for use under overload.
Corrective action
Reduce the load weight.
Note 1: Resetting the inverter initializes the internal heat integrating data of the electronic overcurrent
protection.
Operation Panel
Indication
E.IPF
FR-PU04
Inst. Pwr. Loss
Name
Instantaneous power failure protection
Description
If a power failure occurs for longer than 15ms (this also applies to inverter input
shut-off), the instantaneous power failure protective function is activated to stop
the inverter output in order to prevent the control circuit from malfunctioning. At
this time, the alarm warning output contacts open (across terminals B-C) and
close (across terminals A-C). (Note 2) If a power failure persists for longer than
100ms, the alarm warning 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 15ms.)
Check point
Find the cause of instantaneous power failure occurrence.
Corrective action
•
Remedy the instantaneous power failure.
•
Prepare a backup power supply for instantaneous power failure.
•
Set the function of automatic restart after instantaneous power failure. (Refer
to page 89.)
Note 2: When an instantaneous power failure occurs, the alarm display and alarm output are not provided,
but the inverter performs protective operation to prevent a fault from occurring in itself. In some
operating status (load size, acceleration/deceleration time setting, etc.), overcurrent or other
protection may be activated upon power restoration.