Mitsubishi Electric FR-E700 Instruction Manual page 534

Causes and corrective actions
Warnings
When the protective function is activated, the output is not shut off.
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
7 - 6
OL
Stall prevention (overcurrent)
During When the output current (output torque when Pr. 277 "Stall prevention current
acceleration switchover" = 1) of the inverter exceeds the stall prevention operation level (Pr.
22 "Stall prevention operation level", etc.), this function stops the increase in
frequency until the overload current decreases to prevent the inverter from
resulting in overcurrent trip. When the overload current has reduced below
stall prevention operation level, this function increases the frequency again.
During When the output current (output torque when Pr. 277 "Stall prevention current
constant-speed switchover" = 1) of the inverter exceeds the stall prevention operation level (Pr.
operation 22 "Stall prevention operation level", etc.), this function reduces frequency until
the overload current decreases to prevent the inverter from resulting in over-
current trip. When the overload current has reduced below stall prevention
operation level, this function increases the frequency up to the set value.
During When the output current (output torque when Pr. 277 "Stall prevention current
deceleration switchover" = 1) of the inverter exceeds the stall prevention operation level (Pr.
22 "Stall prevention operation level", etc.), this function stops the decrease in
frequency until the overload current decreases to prevent the inverter from
resulting in overcurrent trip. When the overload current has decreased below
stall prevention operation level, this function decreases the frequency again.
1) Check that the Pr. 0 "Torque boost" setting is not too large.
2) Check that the Pr. 7 "Acceleration time" and Pr. 8 "Deceleration time" settings are not too small.
3) Check that the load is not too heavy.
4) Are there any failure in peripheral devices?
5) Check that the Pr. 13 "Starting frequency" is not too large.
6) Check that the Pr. 22 "Stall prevention operation level" is appropriate.
1) Increase or decrease the Pr. 0 "Torque boost setting" 1% by 1% and check the motor status.
(Refer to section 6.3.1.)
2) Set a larger value in Pr. 7 "Acceleration time" and Pr. 8 "Deceleration time". (Refer to section
6.7.1.)
3) Reduce the load weight.
4) Try advanced magnetic flux vector control and general-purpose magnetic flux vector control.
5) Change the Pr. 14 "Load pattern selection" setting.
6) Set stall prevention operation current in Pr. 22 "Stall prevention operation level". (The initial
value is 150%.) The acceleration/deceleration time may change. Increase the stall prevention
operation level with Pr. 22 "Stall prevention operation level", or disable stall prevention with Pr.
156 "Stall prevention operation selection". (Operation at OL occurrence can be selected using
Pr. 156.)
oL
Stall prevention (overcurrent)
During
If the regenerative energy of the motor becomes excessive and exceeds
deceleration
the regenerative energy consumption capability, this function stops the
decrease in frequency to prevent over voltage shut-off. As soon as the
regenerative energy has decreased, deceleration resumes.
If the regenerative energy of the motor becomes excessive when
regeneration avoidance function is selected (Pr. 882 = 1), this function
increases the speed to prevent over voltage shut-off. (Refer to
section 6.20.4).
Check for sudden speed reduction.
Check that regeneration avoidance function (Pr. 882, Pr. 883, Pr. 885, Pr. 886) is used. (Refer to
section 6.20.4.)
The deceleration time may change. Increase the deceleration time using Pr. 8 "Deceleration time".
FR-PU04
OL
FR-PU07
FR-PU04
oL
FR-PU07
Troubleshooting