Mitsubishi Electric FR-E720-0.1K Instruction Manual page 48

Function Name
One of the three phases on the inverter input side
has been lost. It may also appear if phase-to-
Input phase loss
phase voltage of the three-phase power input has
become largely unbalanced.
The output frequency has dropped to 1Hz as a
Stall prevention stop
result of deceleration due to the excess motor load.
A fault has occurred in the brake circuit, such as a
Brake transistor alarm
brake transistor breakage.(In this case, the
detection
inverter must be powered off immediately.)
Output side earth (ground) An earth (ground) fault has occurred on the
fault overcurrent at start inverter's output side (detected only at a start).
One of the three phases (U, V, W) on the inverter's
Output phase loss output side (load side) has been lost during
inverter operation.
External thermal relay The external thermal relay connected to the OH
operation signal has been activated.
Appears when Pr. 296 Password lock level = "0 or
Option fault
100".
Ethernet communication A communication line error has occurred on the
fault Ethernet board.
A contact fault or other failure has occurred in the
connector between the inverter and the Ethernet
Ethernet board fault
board. The setting of the switch for manufacturer
setting on the Ethernet board has been changed.
Operation of the component where parameters
Parameter storage
are stored (control circuit board) has become
device fault
abnormal.
The control circuit board and the main circuit
Internal board fault
board do not match.
 A communication error has occurred between
the PU and the inverter.
 The communication interval has exceeded the
PU disconnection permissible time period during RS-485
communication via the PU connector.
 The number of communication errors has
exceeded the number of retries.
Operation restart within the set number of retries
Retry count excess
has failed.
Description
 Wire the cables properly.
 Repair a break portion in the cable.
 Check the Pr. 872 Input phase loss protection selection setting.
 Set Pr. 872 Input phase loss protection selection = "0" (without
input phase loss protection) when three-phase input voltage is
largely unbalanced.
Reduce the load. (Check the Pr. 22 Stall prevention operation level
setting.)
Replace the inverter.
Remedy the ground fault portion.
 Wire the cables properly.
 If the motor capacity is smaller than the inverter capacity,
choose the inverter and motor capacities that match.
 If the motor is coasting, stop the motor, then input a start
command. Alternatively, use the automatic restart after
instantaneous power failure/flying start function.
 Reduce the load and operate less frequently.
 Even if the relay contacts are reset automatically, the inverter
will not restart unless it is reset.
 Set Pr. 296 Password lock level  "0 or 100".
 If the problem still persists after taking the above measure,
contact your sales representative.
 Check that the Ethernet cable is correctly connected to the
Ethernet connector. Check that the Ethernet cable is not
broken.
 Set a larger value in Pr.852 Ethernet communication check time
interval.
 When excessive noise occurs around the inverter, change the
communication setting of the master. (The noise may be
reduced by setting a shorter timeout period or increasing the
number of retries in the communication setting of the master.)
 When the CC-Link IE Field Network Basic is used, set a
timeout period longer than the period during which the inverter
does not receive the data addressed to the own station.
 When the CC-Link IE Field Network Basic is used, turn ON the
status bit of the cyclic transmission addressed to the own
station.
 Connect the Ethernet board securely.
 Take measures against noises if there are devices producing
excess electrical noises around the inverter.
If the situation does not improve after taking the above
measure, please contact your sales representative.
 Set the manufacturer setting switch on the Ethernet board
back to the initial setting.
Please contact your sales representative.
When performing parameter writing frequently for
communication purposes, set "1" in Pr. 342 Communication
EEPROM write selection to enable RAM write. Note that powering
OFF returns the inverter to the status before RAM write.
Please contact your sales representative.
(For parts replacement, consult the nearest Mitsubishi Electric
FA Center.)
 Connect the parameter unit cable securely.
 Check the communication data and communication settings.
 Increase the Pr. 122 PU communication check time interval
setting, or set "9999" (no communication check).
Eliminate the cause of the error preceding this error indication.
List of fault displays
Corrective action Display
8
44