Speed control under Real sensorless vector control, vector control, PM sensorless vector control
Trip during torque limit operation (Pr. 874)
● A trip can be set for when the torque limit is activated and the motor stalls.
● When a high load is applied and the torque limit is activated under speed control or position
control, the motor stalls. At this time, if a state where the rotation speed is lower than the value
set in Pr. 865 "Low speed detection" and the output torque exceeds the level set in Pr. 874 "OLT
level setting" continues for 3 s, Stall prevention stop (E.OLT) is activated and the inverter output
is shut off.
Under V/F control or Advanced magnetic flux vector control, if the output frequency drops to
0.5 Hz due to the stall prevention operation and this state continues for 3 s, a fault indication
(E.OLT) appears, and the inverter output is shut off. This operation is activated regardless of the
Pr. 874 setting.
This fault does not occur under the torque control.
Adjusting the stall prevention operation signal and output timing (OL signal, Pr. 157)
● If the output torque exceeds the torque limit level and the torque limit is activated, the stall
prevention operation signal (OL signal) is turned ON for 100 ms or longer. When the output torque
drops to the torque limit level or lower, the output signal also turns OFF.
● Pr. 157 "OL signal output timer" can be used to set whether to output the OL signal immediately,
or whether to output it after a certain time period has elapsed.
Pr. 157 setting
0 (Initial value)
0.1 to 25
Start signal (STF)
Fault signal (ALM)
Alarm stop when torque limit is activated
Setting of parameter 157
Output after the set time (s).
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