Mitsubishi Electric FR-A700 Instruction Manual page 143

Causes and corrective actions
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
*2 Functions only when any of Pr. 178 to Pr. 189 (input terminal function selection) is set to OH.
Operation Panel
Indication
Name
Description
Check point
Corrective action
138
E.OLT
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)
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 section 4 of the Instruction Manual (applied).)
· Check that the Pr. 865 Low speed detection and Pr. 874 OLT level setting values are correct. (Check the
Pr. 22 Stall prevention operation level setting if V/F control is exercised.)
· Reduce the load weight.
· Change the Pr. 22 Stall prevention operation level, Pr. 865 Low speed detection and Pr. 874 OLT level
setting values. (Check the Pr. 22 Stall prevention operation level setting if V/F control is exercised.)
E.GF
Output side earth (ground) fault overcurrent
This function stops the inverter output if an earth (ground) fault overcurrent flows due to an earth
(ground) fault that occurred on the inverter's output (load) side.
Check for an earth (ground) fault in the motor and connection cable.
Remedy the earth (ground) fault portion.
E.LF
Output phase failure
This function stops the inverter output if one of the three phases (U, V, W) on the inverter's output side
(load side) opens.
· Check the wiring (Check that the motor is normal.)
· Check that the capacity of the motor used is not smaller than that of the inverter.
· Wire the cables properly.
· Check the Pr. 251 Output phase failure protection selection setting.
E.OHT
External thermal relay operation
If the external thermal relay provided for motor overheat protection, or the internally mounted
temperature relay in the motor, etc. switches on (contacts open), the inverter output is stopped.
· Check for motor overheating.
· 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.
· Even if the relay contacts are reset automatically, the inverter will not restart unless it is reset.
E.PTC
PTC thermistor operation
Appears when the motor overheat status is detected for 10s or more by the external PTC thermistor
input connected to the terminal AU.
· Check the connection between the PTC thermistor switch and thermal protector.
· Check the motor for operation under overload.
· Is valid setting ( = 63) selected in Pr. 184 AU terminal function selection ? (Refer to section 4 of
Instruction Manual (applied).)
Reduce the load weight.
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
*2
FR-PU04 Fault 14
FR-PU07 PTC activated