Fault Detection (Fatal Errors)

   The Inverter will detect the following faults if the Inverter or motor burns or the internal circuitry of the Invertermal functions. When the Inverter detects a fault, the fault code will be displayed on the digital operator, the fault contact (relay) output will operate, and the Inverter output will be shut off causing the motor to coast to a stop.

   The stopping method can be selected for some faults, and the selected stopping method will be used with these faults. If a fault has occurred, refer to the following table to identify and correct the cause of the fault. Use one of the following methods to reset the fault after restarting the Inverter. If the operation command is being input, however, the reset signal will be ignored.

The refore, be sure to reset the fault with the operation command turned OFF.
S Turn ON the fault reset signal. Amulti-function input (n050 to n056)must be set to 5 (Fault Reset).
S Press the STOP/RESET Key on the Digital Operator.
S Turn the main circuit power supply OFF and then ON again.

oc Overcurrent (OC)
The Inverter output current is as high as or higher than 250% of the rated output current.
• A short-circuit or ground fault has occurred and at the Inverter output.
+ Check and correct the motor power cable.
• The V/f setting is incorrect.
+ Reduce the V/f set voltage.
• The motor capacity is too large for the Inverter.
+ Reduce the motor capacity to the maximum applicable motor capacity.
• The magnetic contactor on the output side of the Inverter has been opened and closed.
+ Rearrange the sequence so that the magnetic contactor will not open or close while the Inverter has current output.
• The output circuit of the Inverter is damaged.
+ Replace the Inverter.
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oU Overvoltage (OV)
The main circuit DC voltage has reached the overvoltage detection level (410 V DC for 200-V Inverters, 820 V DC for 400-V Inverters)
• There is excessive regenerative energy with no braking resistor or Braking Resistor Unit connected.
+ Connect the Braking Resistor Unit or a braking resistor.
+ Increase the deceleration time.
• The regenerative energy has not been processed though a braking resistor or Braking Resistor Unit.
+ Set n092 for stall prevention during deceleration to 1 (disable)
• The braking resistor or Braking Resistor Unit is not wired properly.
+ Check and correct the wiring.
• The power supply voltage is too high.
+ Decrease the voltage so it will be within specifications.
• There is excessive regenerative energy due to overshooting at the time of acceleration.
+ Suppress the overshooting as much as possible.
• The braking transistor is damaged.
+ Change the Inverter.
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uU1 Main circuit undervoltage (UV1)
The main circuit DC voltage has reached the undervoltage detection level (200 V DC for the 3G3MV-C2j, 160 V DC for the 3G3MV-CBj, and 400 V DC for the 3G3MV-C4j).
• Power supply to the Inverter has phase loss, power input terminal screws are loose, or the power cable is disconnected.
+ Check the above and take necessary countermeasures.
• Incorrect power supply voltage
+ Make sure that the power supply voltage is within specifications.
• Momentary power interruption has occurred.
+ Use the momentary power interruption compensation (Set n081 so that the Inverter restarts after power is restored)
+ Improve the power supply.
• The internal circuitry of the Inverter is damaged.
+ Change the Inverter.
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uU2 Control power supply undervoltage (UV2)
The control power supply voltage has reached the undervoltage detection level.
• Internal circuit fault.
+ Turn the Inverter OFF and ON.
+ Change the Inverter if the same fault occurs again.
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oh Radiation fin overheated (OH)
The temperature of the radiation fins of the Inverter has reached 110_C ± 10_C.
• The ambient temperature is too high.
+ Ventilate the Inverter or install a cooling unit.
• The load is excessive.
+ Reduce the load.
+ Change the inverter to one with a higher capacity.
• The V/f setting is incorrect.
+ Reduce the V/f set voltage.
• The acceleration/deceleration time is too short.
+ Increase the acceleration/deceleration time.
• The ventilation is obstructed.
+ Change the location of the Inverter to meet the installation conditions.
• The cooling fan of the Inverter does not work.
+ Replace the cooling fan.
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ol1 Motor overload (OL1)
The electric thermal relay actuated the motor overload protective function.
Calculate the heat radiation of the motor from the output current of the Inverter based on the rated motor current (n036), motor protection characteristics (n037), and motor protective time setting (n038).
• The load is excessive.
+ Reduce the load.
+ Increase the motor capacity.
• The V/f setting is incorrect.
+ Reduce the V/f set voltage.
• The value in n013 for maximum voltage frequency is low.
+ Check the motor nameplate and set n013 to the rated frequency.
• The acceleration/deceleration time is too short.
+ Increase the acceleration/deceleration time.
• The value in n036 for rated motor current is incorrect.
+ Check the motor nameplate and set n036 to the rated current.
• The Inverter is driving more than one motor.
+ Disable the motor overload protective function and install an electronic thermal relay for each of the motors.
The motor overload protective function is disabled by setting n036 to 0.0 or n037 to 2.
• The motor protective time setting in n038 is short.
+ Set n038 to 8 (the default value).
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ol2 Inverter overload (OL2)
The electronic thermal relay has actuated the Inverter overload protective function.
• The load is excessive.
+ Reduce the load.
• The V/f setting is incorrect.
+ Reduce the V/f set voltage.
• The acceleration/deceleration time is too short.
+ Increase the acceleration/deceleration time.
• The VFD capacity is insufficient.
+ Use an Inverter model with a higher capacity.
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ol3 Overtorque detection (OL3)
There has been a current or torque the same as or greater than the setting in n098 for overtorque detection level and that in n099 for overtorque detection time.
A fault has been detected with n096 for overtorque detection function selection set to 2 or 4.
• The mechanical system is locked or has a failure.
+ Check the mechanical system and correct the cause of overtorque.
• The parameter settings were incorrect.
+ Adjust the n098 and n099 parameters according to the mechanical system.
Increase the set values in n098 and n099.
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ef (x) External fault j (EF)
An external fault has been input from a multi-function input.
A multi-function input 1 to 7 set to 3 or 4 has operated.
The EF number indicates the number of the corresponding input (S1 to S7).
• An external fault was input from a multi-function input.
+ Remove the cause of the external fault.
• The sequence is incorrect.
+ Check and change the external fault input sequence including the input timing and NO or NC contact.
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F00 Digital Operator transmission fault 1 (F00)
No communications were possible with the Digital Operator for 5 s or more after the Inverter had been turned ON.
• The Digital Operator may not be mounted properly.
+ Turn OFF the Inverter, dismount and mount the Digital Operator, and turn ON the Inverter.
• The Digital Operator has a failure.
+ Change the Digital Operator.
• The Inverter has a failure.
+ Change the Inverter.
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F01 Digital Operator transmission fault 2 (F01)
A transmission fault continued for 5 s or more after communications with the Digital Operator had failed.
• The Digital Operator may not be mounted properly.
+ Turn OFF the Inverter, dismount and mount the Digital Operator, and turn ON the Inverter.
• The Digital Operator has a failure.
+ Change the Digital Operator.
• The Inverter has a failure.
+ Change the Inverter.
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F04 Initial memory fault (F04)
An error in the built-in EEPROM of the Inverter has been detected.
• The internal circuitry of the Inverter has a fault.
+ Initialize the Inverter with n001 set to 8, 9, 10, or 11 and turn the Inverter OFF and ON.
+ Replace the Inverter if the same fault occurs again.
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F05 Analog-to-digital converter fault (F05)
An analog-to-digital converter fault has been detected.
• The internal circuitry of the Inverter has a fault.
+ Turn the Inverter OFF and ON.
+ Replace the Inverter if the same fault occurs again.
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F06 Option Unit fault (F06)
An Option Unit fault was detected.
The Inverter will detect this error if the output or verify signal of the Unit has a fault.
• The Option Unit may not be connected properly.
+ Turn OFF the Inverter, dismount and mount the Option Unit or attachment, and turn ON the Inverter.
• The Option Unit has a failure.
+ Change the Option Unit.
• The attachment has a failure.
+ Change the attachment.
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F07 Digital Operator fault (F07)
An error in the built-in control circuit of the Digital Operator has been detected.
The EEPROM of the Digital Operator or the analog-to-digital converter has a failure.
• The internal circuitry of the Digital Operator has a fault.
+ Turn the Digital Operator OFF and ON.
+ Replace the Digital Operator if the same fault occurs again.
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opr Digital Operator connection error (OPR)
The Inverter will detect this error if n010 for Digital
Operator connection error processing selection is set to 1.
• The Digital Operator may not be mounted properly.
+ Turn OFF the Inverter, dismount and mount the Digital Operator, and turn ON the Inverter.
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ce Communications time-over (CE)
Normal RS-422/485 communications were not established within 2 s.
The Inverter will detect this error if n151 for RS-422/485 communications time over detection selection is set to 0, 1, or 2.
• A short-circuit, ground fault, or disconnection has occurred on the communications line.
+ Check and correct the line.
• The termination resistance setting is incorrect.
+ In the case of RS-422 communications, set pin 1 of SW2 of all Inverters to ON. In the case of RS-485 communications, set pin 1 of SW2 of only the Inverter located at each end of the network to ON.
• Noise influence.
+ Do not wire the communications line along with power lines in the same conduit.
+ Use the twisted-pair shielded wire for the communications line, and ground it at the Master.
• Master’s program error.
+ Check and correct the program so that communications will be performed more than once every 2-s period.
• Communications circuit damage.
+ If the same error is detected as a result of a self-diagnostic test, change the Inverter.
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srP Emergency stop (STP)
An emergency stop alarm is input to a multi-function input.
(A multi-function input from 1 to 7 that was set to 19 or 21 has operated.)
• An emergency stop alarm is input.
+ Remove the cause of the fault.
• The sequence is incorrect.
+ Check and change the external fault input sequence including the input timing and NO or NC contact.
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FbL Feedback loss fault (FbL)
A feedback input was interrupted during PID control execution. (This fault is detected when an input level below the feedback loss detection level set in n137 persists for longer than the
feedback loss detection time set in n138.)
• Feedback wiring error.
+ Check for and correct any cable disconnection or faulty wiring.
• Feedback sensor error
+ Check sensor status and replace any defective sensors.
• PID target value input error or feedback loss detection setting error
+ Correct the target value input so that it is outside of the feedback loss detection range. Correct the feedback loss detection parameter settings (n137, n138).
• Feedback input circuit error
+ Replace the Inverter.
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(PF) Main circuit voltage fault
The main circuit DC voltage has oscillated erroneously when regeneration was not being performed.
This fault is detected when a voltage fluctuation greater than the input open-phase detection level set in n166 persists for longer than the input open-phase detection time set in n167.
• Momentary power failure.
+ Either apply countermeasures against momentary power failures or disable the input open-phase detection.
• Input power supply open phase.
+ Check for and correct any main circuit power supply disconnections or faulty wiring.
• Excessive input power supply voltage fluctuation or bad line voltage balance.
+ Check the power supply voltage. Apply measures to stabilize the power supply, or disable the input open-phase detection.
• Main circuit capacitor failure.
+ If this fault is occurring frequently and there is no error at the power supply, replace the Inverter or disable the input open-phase detection. (Also check the usage time with the accumulated operating time function.)
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(LF) Output open-phase fault
An open phase has occurred at the Inverter’s output.
This fault is detected when a current in any of the Inverter output phases less than the output open-phase detection level set in n168 persists for longer than the output open-phase detection time set in n169.
• Output cable is disconnected.
+ Check for and correct any output cable disconnections or faulty wiring.
• Motor winding disconnected.
+ Check the motor’s line resistance. If winding is broken, replace the motor.
• Output terminal screws are loose.
+ Check and tighten the output terminal screws.
• Inverter output transistor open breakdown.
+ Replace the Inverter.
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GF Ground fault (GF)
The ground current at the Inverter has exceeded approximately 50% of the Inverter’s rated output current.
• Motor burnout or insulation damage.
+ Check the motor’s insulation resistance. If conducting, replace the motor.
• Cable is damaged.
+ Check the resistance between the cable and FG. If conducting, replace the cable.
• Cable and FG floating capacity
+ If the cable is longer than 100 m, lower the (PWM) carrier frequency.
+ Apply measures to reduce the floating capacity.
Don’t use metal ducts, use a separate cable for each phase, include an AC reactor in the output side, etc.
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SC Load short circuit (SC)
The Inverter output or load is short-circuited.
• Motor burnout or insulation damage.
+ Check the resistance between the motor phases. If abnormal, replace the Inverter.
• Cable is damaged.
+ Check the resistance between the cables. If conducting, replace the cable.
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BUS Communications error (Option Unit)
A communications error occurred at the Option Unit.
• Communications cable wired incorrectly, short-circuited, or disconnected.
+ Check and correct the communications cable wiring.
• Data destroyed by noise.
+ Change to a dedicated communications cable or to shielded cable, and mask the shield or ground it at the power supply.
+ Use a dedicated communications power supply, and connect a noise filter to the power supply input side.
• Option Unit is damaged.
+ If communications errors frequently occur and there is no problem with the wiring, replace the Option Unit.
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OFF Power supply error
Control power supply voltage is insufficient.
• No power supply is provided.
+ Check and correct the power supply wire and voltage.
• Terminal screws are loose.
+ Check and tighten the terminal screws.
• Operator connectors are faulty.
+ If only the Operator indicator is not lit, (i.e., if the RUN and ALARM indicators are lit), check and correct the Operator’s connectors.
• The Inverter is damaged.
+ Replace the Inverter.

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