Mitsubishi Electric 800 Series Instruction Manual page 265

 To further prevent a trip (Pr.154)
V/F V/F V/F Magnetic flux Magnetic flux Magnetic flux
• When Pr.154 Voltage reduction selection during stall prevention operation = "0, 10", the output voltage is reduced.
By making this setting, an overcurrent trip becomes less likely to occur. Use this setting when torque reduction does not
pose a problem. (Under V/F control, the output voltage is reduced only during the stall prevention operation is activated.)
• Set Pr.154 = "10, 11" when the overvoltage protective function (E.OV[ ]) activates during stall prevention operation in an
application with large load inertia. Note that turning OFF the start signal (STF/STR) or varying the frequency command
during stall prevention operation may delay the acceleration/deceleration start.
Pr.154 E.OC[ ] countermeasure
0 Effective
1 (initial value) ―
10 Effective
11 ―
 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 the rotation speed is lower
than 1.5 Hz and the output torque exceeds the level set in Pr.874 OLT level setting and such a state continues for 3 s,
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 s, 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 a test run. 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 selection
Pr.178 to Pr.189 (Input terminal function selection)
Pr.190 to Pr.196 (Output terminal function selection)
Pr.858 Terminal 4 function assignment, Pr.868 Terminal 1 function assignment
264
5. PARAMETERS
5.7 (H) Protective function parameter
E.OV[ ] countermeasure
―
―
Effective
Effective
Torque
Pr.874
Output torque
Output
frequency
1.5 Hz
Start signal
(STF)
Fault signal
(ALM)
page 318
page 343
page 297
Stall prevention limit
Time
Time
3 s
E.OLT occurs
page 322