Mitsubishi Electric FR-A700 Instruction Manual page 726

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 - 8
OL
Stall prevention (overcurrent)
During When the output current (output torque during real sensorless vector con-
acceleration trol or vector control) 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 shut-off. When the overload current
has decreased below stall prevention operation level, this function
increases the frequency again.
During When the output current (output torque during real sensorless vector
constant-
control or vector control) of the inverter exceeds the stall prevention
speed
operation level (Pr. 22 "Stall prevention operation level", etc.), this
operation
function reduces frequency until the overload current decreases to
prevent the inverter from resulting in overcurrent shut-off. When the
overload current has decreased below stall prevention operation
level, this function increases the frequency up to the set value.
During When the output current (output torque during real sensorless vector con-
deceleration trol or vector control) 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 shut-off. 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.
Check the motor for use under overload.
1) Increase or decrease the Pr. 0 "Torque boost setting" 1% by 1% and check the motor
status. (Refer to section 6.2.1.)
2) Set a larger value in Pr. 7 "Acceleration time" and Pr. 8 "Deceleration time". (Refer to
section 6.11.1.)
3) Reduce the load weight.
4) Try advanced magnetic flux vector control, real sensorless vector control or 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 ini-
tial value is 110%.)
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". (Use Pr. 156 to set either operation continued or
not at OL operation.)
oL
Stall prevention (overcurrent)
During
If the regenerative energy of the motor becomes excessive and
deceleration
exceeds 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 6.24.8.)
Check for sudden speed reduction.
Regeneration avoidance function (Pr. 882 to Pr. 886) is being used? (Refer to
section 6.24.8).
The deceleration time may change. Increase the deceleration time using Pr. 8 "Decelera-
tion time".
FR-PU04
OL
FR-PU07
FR-PU04
oL
FR-PU07
Troubleshooting