Mitsubishi Electric FR-A820-00046 (0.4K), Instruction Manual

Page: 1054 / 1218

Causes and corrective actions Protective functions
6 - 14
6.5.2 Warning
Output is not shut off when a protective function activates.
Operation panel
indication
OL FR-LU-08 OL
Name Stall prevention (overcurrent)
Description
앫
When the output current of the inverter increases, the stall prevention (overcurrent)
function activates.
앫
The following section explains about the stall prevention (overcurrent) function.
During
acceleration
When the output current (output torque under Real sensorless vector
control or vector control) of the inverter exceeds the stall prevention
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
constant-speed
operation
When the output current (output torque under Real sensorless vector
control or vector control) of the inverter exceeds the stall prevention
level (Pr. 22 "Stall prevention operation level", etc.), this function reduces
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 up to the set value.
During
deceleration
When the output current (output torque under Real sensorless vector
control or vector control) of the inverter exceeds the stall prevention
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.
Check point
앫
Check that the Pr. 0 "Torque boost" setting is not too large.
앫
The Pr. 7 "Acceleration time" and Pr. 8 "Deceleration time" settings may be too short.
앫
Check that the load is not too heavy.
앫
Check for any failures in peripheral devices.
앫
Check that the Pr. 13 "Starting frequency" is not too large.
앫
Check that Pr. 22 "Stall prevention operation level" is appropriate.
Corrective action
앫
Gradually increase or decrease the Pr. 0 setting by 1% at a time and check the motor
status.(Refer to page 5-688.)
앫
Set a larger value in Pr. 7 "Acceleration time" and Pr. 8 "Deceleration time".
(Refer to page 5-241.)
앫
Reduce the load.
앫
Try Advanced magnetic flux vector control, Real sensorless vector control, or vector control.
앫
Change the Pr. 14 "Load pattern selection" setting.
앫
The stall prevention operation current can be set in Pr. 22 "Stall prevention operation level".
(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". (Use Pr. 156 to set either
operation continued or not at OL operation.)