Mitsubishi Electric FR-A700 Instruction Manual page 417

Operation Panel
Indication
Name
Stall prevention
If the frequency has fallen to 0.5Hz by stall prevention operation and remains for 3s, an alarm (E.OLT)
appears to shutoff the inverter output. OL appears while stall prevention is being activated.
When speed control is performed by real sensorless vector control or vector control, an alarm (E.OLT)
Description
is displayed and the inverter output is stopped if frequency drops to the Pr. 865 Low speed detection
(initial value is 1.5Hz) setting by torque limit operation and the output torque exceeds Pr. 874 OLT level
setting (initial value is 150%) setting and remains for more than 3s.
· Check the motor for use under overload. (Refer to page 150.)
Check point
· Check that the Pr. 865 Low speed detection and Pr. 874 OLT level setting values are correct. (Check the
· Reduce the load weight.
Corrective action
· Change the Pr. 22 Stall prevention operation level, Pr. 865 Low speed detection and Pr. 874 OLT level
Operation Panel
Indication
Name
Output side earth (ground) fault overcurrent
This function stops the inverter output if an earth (ground) fault overcurrent flows due to an earth
Description
(ground) fault that occurred on the inverter's output (load) side.
Check point
Check for an earth (ground) fault in the motor and connection cable.
Corrective action
Remedy the earth (ground) fault portion.
Operation Panel
Indication
Name Output phase failure
This function stops the inverter output if one of the three phases (U, V, W) on the inverter's output side
Description
(load side) opens.
· Check the wiring (Check that the motor is normal.)
Check point
· Check that the capacity of the motor used is not smaller than that of the inverter.
· Wire the cables properly.
Corrective action
· Check the Pr. 251 Output phase failure protection selection setting.
Operation Panel
Indication
Name
External thermal relay operation
If the external thermal relay provided for motor overheat protection, or the internally mounted
Description
temperature relay in the motor, etc. switches on (contacts open), the inverter output is stopped.
· Check for motor overheating.
Check point
· Check that the value of 7 (OH signal) is set correctly in any of Pr. 178 to Pr. 189 (input terminal function selection).
· Reduce the load and operating duty.
Corrective action
· Even if the relay contacts are reset automatically, the inverter will not restart unless it is reset.
*3 Functions only when any of Pr. 178 to Pr. 189 (input terminal function selection) is set to OH.
Operation Panel
Indication
Name
PTC thermistor operation
Appears when the motor overheat status is detected for 10s or more by the external PTC thermistor
Description
input connected to the terminal AU.
· Check the connection between the PTC thermistor switch and thermal protector.
Check point
· Check the motor for operation under overload.
· Is valid setting ( = 63) selected in Pr. 184 AU terminal function selection ? (Refer to page 184, 228.)
Corrective action
Reduce the load weight.
E.OLT
Pr. 22 Stall prevention operation level setting if V/F control is exercised.)
setting values. (Check the Pr. 22 Stall prevention operation level setting if V/F control is exercised.)
E.GF
E.LF
E.OHT
E.PTC
Causes and corrective actions
FR-PU04
Stll Prev STP ( OL shown during stall
prevention operation)
FR-PU07
FR-PU04
Ground Fault
FR-PU07
FR-PU04
⎯⎯
FR-PU07
FR-PU04
OH Fault
FR-PU07
*3
FR-PU04 Fault 14
FR-PU07 PTC activated
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