Mitsubishi Electric 800 Series Instruction Manual page 580

Abbreviation E.OLT
Name Stall prevention stop
Description
V/F V/F V/F
If the output frequency has fallen to 0.5 Hz by stall prevention operation and remains for 3 s, a fault (E.OLT)
appears and the inverter trips. OL appears while stall prevention is being activated.
PM PM PM
During speed control, a fault (E.OLT) appears and the inverter trips if the frequency value converted from the
motor rotation speed drops to 1.5 Hz or lower by stall prevention operation and the output torque exceeds the
Pr.874 OLT level setting (refer to
Check point • Check the motor for the use under overload.
• Check that the Pr.874 values are correct. (Check the Pr.22 Stall prevention operation level setting under
V/F control and Advanced magnetic flux vector control.)
• Check if a motor is connected under PM motor control.
Corrective action • Reduce the load.
• Change the Pr.22 and Pr.874 values. (Check the Pr.22 setting under V/F control and Advanced magnetic
flux vector control.)
• For a test run without connecting a motor, select the PM motor control test operation. (Refer to
• Also check that the stall prevention (overcurrent) warning (OL) or the stall prevention (overvoltage) warning
(oL) countermeasure is taken.
Abbreviation E.SOT
Name Loss of synchronism detection
Description The inverter trips when the motor operation is not synchronized. (This function is only available under PM
motor control.)
Check point • Check that the PM motor is not driven overloaded.
• Check if a start command is given to the inverter while the PM motor is coasting.
• Check if a motor is connected under PM motor control.
Corrective action • Set the acceleration time longer.
• Reduce the load.
• Check the connection of the PM motor.
• For a test run without connecting a motor, select the PM motor control test operation. (Refer to
• Offline auto tuning must be performed. (Refer to
Abbreviation E.LUP
Name Upper limit fault detection
Description When the load exceeds the upper limit fault detection range, the inverter trips. This protective function is not
available in the initial setting of Pr.1490 (Pr.1490 = "9999").
Check point • Check if too much load is applied to the equipment.
• Check that the load characteristics settings are correct.
Corrective action • Inspect the equipment.
• Set the load characteristics (Pr.1481 to Pr.1487) correctly.
Abbreviation E.LDN
Name Lower limit fault detection
Description When the load falls below the lower limit fault detection range, the inverter trips. This protective function is not
available in the initial setting of Pr.1491 (Pr.1491 = "9999").
Check point • Check if the equipment load is too light.
• Check that the load characteristics settings are correct.
Corrective action • Inspect the equipment.
• Set the load characteristics (Pr.1481 to Pr.1487) correctly.
Abbreviation E.GF
Name Output side earth (ground) fault overcurrent
Description The inverter trips if an earth (ground) fault overcurrent flows due to an earth (ground) fault that occurred on the
inverter's output side (load side).
Check point Check for an earth (ground) fault in the motor and connection cable.
Corrective action Remedy the earth (ground) fault portion.
Magnetic flux Magnetic flux Magnetic flux
PM PM PM
FR-LU08 Stall prevention STP
FR-PU07 Stll Prev STP
page 257) and remains there for 3 s.
FR-LU08 Motor Step Out
FR-PU07
page 363.)
FR-LU08 Upper limit fault
FR-PU07 E.LUP
FR-LU08 Lower limit fault
FR-PU07 E.LDN
FR-LU08 Ground Fault
FR-PU07
page 145.)
page 145.)
6. PROTECTIVE FUNCTIONS
6.4 Causes and corrective actions
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