Mitsubishi Electric FR-F800 Series Instruction Manual page 298

 Trip during stall prevention operation (Pr.874)
• The inverter can be set to trip at activation of stall prevention and stalling of the motor.
• When a high load is applied and the stall prevention is activated, the motor stalls. At this time, if a state where the motor
rotation speed is lower than 1.5 Hz and the output torque exceeds the level set in Pr.874 OLT level setting continues for
3 seconds, the stall prevention stop (E.OLT) is activated and the inverter output is shut off.
NOTE
• 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 seconds, a fault indication (E.OLT) appears, and the inverter output is shut off. This
operation is activated regardless of the Pr.874 setting.
CAUTION
• Do not set the stall prevention operation current too low.
Doing so will reduce the generated torque.
• Be sure to perform the test operation.
Stall prevention operation during acceleration may extend the acceleration time.
Stall prevention operation during constant-speed operation may cause sudden speed changes.
Stall prevention operation during deceleration may extend the deceleration time.
Parameters referred to
Pr.73 Analog input
Pr.178 to Pr.189 (Input terminal function
Pr.190 to Pr.196 (Output terminal function
Pr.858 Terminal 4 function assignment, Pr.868 Terminal 1 function
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Torque
Output torque
Output
frequency
Start signal
(STF)
Fault signal
(ALM)
selectionpage 349
selection)page 373
selection)page 330
search engine
Stall prevention limit
Pr.874
1.5Hz
3s
E.OLT occurs
assignmentpage 352
PM PM PM
Time
Time
5. PARAMETERS
5.7 (H) Protective function parameter
1
2
3
4
5
6
7
8
9
10
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