Mitsubishi Electric FR-A820-00046 (0.4K), Instruction Manual

Page: 1065 / 1218

Protective functions Causes and corrective actions
FR-A800 6 - 25
Operation panel
indication
E.OLT FR-LU-08 Stall prevention STP
Name Stall prevention stop
Description
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.
When speed control is performed, a fault (E.OLT) appears and the inverter trips if frequency
drops to the Pr. 865 "Low speed detection" (initial value is 1.5 Hz) setting by torque limit
operation and the output torque exceeds the Pr. 874 "OLT level setting" (initial value is 150%)
setting and remains 3 s.
Check point
앫
Check the motor for the use under overload.
앫
Check that the Pr. 865 and Pr. 874 values are correct.
(Check the Pr. 22 "Stall prevention operation level" setting under V/F control and Advanced
magnetic flux vector control.)
앫
Check if a motor is connected under PM sensorless vector control.
Corrective action
앫
Reduce the load.
앫
Change the Pr. 22, Pr. 865, and Pr. 874 values. (Check the Pr. 22 setting under V/F control and
Advanced magnetic flux vector control.)
앫
For a test run without connecting a motor, select the PM sensorless vector control test
operation. (Refer to page 5-65.)
앫
Also check that the stall prevention (overcurrent) warning (OL) or the stall prevention
(overvoltage) warning (oL) countermeasure is taken.
Operation panel
indication
E.SOT
FR-LU-08 Motor step out
Name Loss of synchronism detection
Description
The inverter trips when the motor operation is not synchronized. (This function is only available
under PM sensorless vector control.)
Check point
앫
Check that the PM motor is not driven overloaded.
앫
Check if a start command is given to the inverter while the PM motor is coasting.
앫
Check if a motor is connected under PM sensorless vector control.
앫
Check if a PM motor other than the MM-CF series is driven.
Corrective action
앫
Set the acceleration time longer.
앫
Reduce the load.
앫
If the inverter restarts during coasting, set Pr. 57 "Restart coasting time"
≠
"9999", and select
the automatic restart after instantaneous power failure.
앫
Check the connection of the IPM motor.
앫
For a test run without connecting a motor, select the PM sensorless vector control test
operation. (Refer to page 5-65.)
앫
Drive an IPM motor (MM-CF series)
앫
When driving an IPM motor other than MM-CF series, offline auto tuning must be
performed. (Refer to page 5-471.)
Operation panel
indication
E.LUP FR-LU08 Upper limit fault
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
앫
Check if too much load is applied to the equipment.
앫
Check that the load characteristics settings are correct.
Corrective action
앫
Inspect the equipment.
앫
Set the load characteristics (Pr. 1481 to Pr. 1487) correctly.
V/F V/F V/F Magnetic flux Magnetic flux Magnetic flux
Sensorless Sensorless Sensorless Vector Vector Vector PM PM PM
PM PM PM