147
Causes and corrective actions
*1
Resetting the inverter initializes the internal thermal integrated data of the electronic thermal relay function.
Operation Panel
Indication
E.OV3
FR-PU04
FR-PU07
OV During Dec
Name
Regenerative overvoltage trip 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. The circuit may also be
activated by a surge voltage produced in the power supply system. Protective circuit may activate even
if the regeneration converter is not activated due to power supply failure (Input phase failure and
instantaneous power failure).
Check point
· Check for power supply fault or wrong wiring.
· Check for sudden speed reduction.
Corrective action
· Perform wiring correctly.
· Increase the deceleration time. (Set the deceleration time which matches the moment of inertia of
the load)
· Decrease the braking duty.
· Use regeneration avoidance function
(Pr. 882 to Pr. 886)
.
(Refer to chapter 4 of
the instruction
manual (applied).)
Operation Panel
Indication
E.THT
FR-PU04
FR-PU07
Inv. Overload
Name
Inverter overload trip (electronic thermal relay function)
Description
If a current not less than 150% of the rated output current flows and overcurrent trip does not occur
(220% or less), the electronic thermal relay activate to stop the inverter output in order to protect the
output transistors. (Overload capacity 150% 60s inverse-time characteristics)
Check point
1.Check that acceleration/deceleration time is not too short.
2.Check that torque boost setting is not too large (small).
3.Check that load pattern selection setting is appropriate for the load pattern of the using machine.
4.Check the motor for use under overload.
Corrective action
1.Increase acceleration/deceleration time.
2.Adjust the torque boost setting.
3.Set the load pattern selection setting according to the load pattern of the using machine.
4.Reduce the load weight.
Operation Panel
Indication
E.THM
FR-PU04
FR-PU07
Motor Ovrload
Name
Motor overload trip (electronic thermal relay function)
Description
The electronic thermal relay function in the inverter detects motor overheat due to overload or reduced
cooling capability during constant-speed operation and pre-alarm (TH display) is output when the I
2
t
value reaches 85% of the
Pr. 9 Electronic thermal O/L relay
setting and the protection circuit is activated
to stop the inverter output when the I
2
t value reaches the specified value. When running a special
motor such as a multi-pole motor or two motors, provide a thermal relay on the inverter output side
since such motor(s) cannot be protected by the electronic thermal relay function.
Check point
1. Check the motor for use under overload.
2. Check that the setting of
Pr. 71 Applied motor
for motor selection is correct.
(Refer to chapter 4 of
the instruction manual (applied).)
3. Check that stall prevention operation setting is correct.
Corrective action
1. Reduce the load weight.
2. For a constant-torque motor, set the constant-torque motor in
Pr. 71 Applied motor
.
3. Check that stall prevention operation setting is correct.
(Refer to chapter 4 of
the instruction manual
(applied).)
Summary of Contents for FR-A741-11K
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