Mitsubishi Electric FR-F800 Series Instruction Manual page 605

Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
Operation panel
indication
Name
Description
Check point
Corrective action
604
6. PROTECTIVE FUNCTIONS
6.5 Causes and corrective actions
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E.OLT
Stall prevention stop
V/F V/F V/F Magnetic flux Magnetic flux Magnetic flux
If the output frequency has fallen to 0.5 Hz by stall prevention operation and remains for 3 seconds, a fault
(E.OLT) appears and the inverter is shut off. OL appears while stall prevention is being activated.
PM PM PM
During speed control, a fault (E.OLT) appears and the inverter output is shut off 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 the motor for the use under overload.
• Check that the Pr.874 setting is 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.
• Reduce the load.
• Change the Pr.22 (Pr.874)setting. (Check the Pr.22 setting under V/F control and Advanced magnetic flux
vector control.)
• For the test operation without connecting a motor, select the PM motor control test operation. (Refer to
177.)
• Also check that the stall prevention (overcurrent) warning (OL) or the stall prevention (overvoltage) warning
(oL) countermeasure is taken.
E.SOT
PM PM PM
Loss of synchronism detection
The inverter output is shut off when the motor operation is not synchronized. (This function is only available under
PM motor control.)
• 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.
• Check if a PM motor other than the MM-EFS or MM-THE4 series is driven.
• Set the acceleration time longer.
• Reduce the load.
• If the inverter restarts during coasting, set Pr.57 Restart coasting time ≠ "9999", and select the automatic
restart after instantaneous power failure.
• Check the connection of the IPM motor.
• For the test operation without connecting a motor, select the PM motor control test operation. (Refer to
177.)
• Drive an IPM motor (MM-EFS or MM-THE4 series).
• When driving a PM motor other than the MM-EFS or MM-THE4 series, offline auto tuning must be performed.
(Refer to page 392.)
E.LUP
Upper limit fault detection
The inverter output is shut off when the load exceeds the upper limit fault detection range. This protective
function is not available in the initial setting of Pr.1490 (Pr.1490 = "9999").
• Check if too much load is applied to the equipment.
• Check that the load characteristics settings are correct.
• Inspect the equipment.
• Set the load characteristics (Pr.1481 to Pr.1487) correctly.
E.LDN
Lower limit fault detection
The inverter output is shut off when the load falls below the lower limit fault detection range. This protective
function is not available in the initial setting of Pr.1491 (Pr.1491 = "9999").
• Check if the equipment load is too light.
• Check that the load characteristics settings are correct.
• Inspect the equipment.
• Set the load characteristics (Pr.1481 to Pr.1487) correctly.
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FR-LU08 indication Stall prevention STP
page 290) and remains there for 3 s.
FR-LU08 indication Motor Step Out
FR-LU08 indication Upper limit fault
FR-LU08 indication Lower limit fault
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