Mitsubishi FR-A701 Fault Codes List
Access the complete reference guide for Mitsubishi FR-A701 vector drive fault codes. Learn to diagnose E.OC1 errors, use FR Configurator2, and interpret operation panel alarms.
Mitsubishi FR-A701 Fault Codes Reference Table
Use the search bar below or browse the table to identify your specific error code.
| Fault Code | Cause & Solution |
| HOLD Operation panel lock |
Cause: Operation lock mode is set. Operation other than STOP/RESET
is invalid. Solution: - Press MODE for 2s to release lock. |
| LOCD Password locked |
Cause: Password function is active. Display and setting of parameter
is restricted. Solution: - Enter the password in Pr. 297 Password lock/unlock to unlock the password function before operating. |
| Er1 Write disable error |
Cause: - You attempted to make parameter setting when Pr. 77 Parameter write selection has been set to disable parameter write. - Frequency jump setting range overlapped. - Adjustable 5 points V/F settings overlapped - The PU and inverter cannot make normal communication Solution: - Check the setting of Pr. 77 Parameter write selection - Check the settings of Pr. 31 to 36 (frequency jump). - Check the settings of Pr. 100 to Pr. 109 (adjustable 5 points V/F). - Check the connection of the PU and inverter. |
| Er2 Write error during operation |
Cause: When parameter write was performed during operation with a
value other than "2" (writing is enabled independently of operating
status in any operation mode) is set in Pr. 77 and the STF (STR) is ON. Check point: - Check the Pr. 77 setting. - Check that the inverter is not operating. Solution: - Set "2" in Pr. 77. - After stopping operation, make parameter setting. |
| Er3 Calibration error |
Cause: Analog input bias and gain calibration values are too
close. Check point: - Check the settings of C3, C4, C6 and C7 (calibration functions). |
| Er4 Mode designation error |
Cause: - Appears if a parameter setting is attempted in the External or NET operation mode with Pr. 77 ≠ "2". - Appears if a parameter setting is attempted when the command source is not at the operation panel. (FR- DU07). Check point: - Check that operation mode is "PU operation mode". - Check the Pr. 77 setting. - Check the Pr. 551 setting. Solution: - After setting the operation mode to the "PU operation mode", make parameter setting. - After setting Pr. 77 = "2", make parameter setting. - Set Pr.551 = "2 (initial value)". |
| rE1 Parameter read error |
Cause: Description An error occurred in the EEPROM on the operation
panel side during parameter copy reading. Solution: - Make parameter copy again. - Check for an operation panel (FR-DU07) failure. |
| rE2 Parameter write error |
Cause: - You attempted to perform parameter copy write during operation. - An error occurred in the EEPROM on the operation panel side during parameter copy writing. Check point: - Is the FWD or REV LED of the operation panel (FR-DU07) lit or flickering? Solution: - After stopping operation, make parameter copy again. - Check for an operation panel (FR-DU07) failure. |
| rE3 Parameter verification error |
Cause: - Data on the operation panel side and inverter side are different. - An error occurred in the EEPROM on the operation panel side during parameter verification. Check point: - Check for the parameter setting of the source inverter and inverter to be verified. Solution: - Press SET button to continue verification. Make parameter verification again. - Check for an operation panel (FR-DU07) failure. |
| rE4 Model error |
Cause: - A different model was used for parameter write and verification during parameter copy. - When parameter copy write is stopped after parameter copy read is stopped Check point: - Check that the verified inverter is the same model. - Check that the power is not turned OFF or an operation panel is not disconnected, etc. during parameter copy read. Solution: - Use the same model (FR-A701 series) for parameter copy and verification. ·- Perform parameter copy read again. |
| Err. | Cause: - The RES signal is on - The PU and inverter cannot make normal communication (contact fault of the connector) - When the voltage drops in the inverter's input side. - When the control circuit power (R1/L11, S1/L21) and the main circuit power (R/L1, S/L2, T/L3) are connected to a separate power, it may appear at turning ON of the main circuit. It is not a fault. Solution: - Turn OFF the RES signal. - Check the connection of the PU and inverter. - Check the voltage on the inverter's input side. |
| OL Stall prevention (overcurrent) |
Cause: - During acceleration: When the output current (output torque during Real sensorless vector control or vector control) of the inverter exceeds the stall prevention operation level (Pr. 22 Stall prevention operation level, etc.), this function stops the increase in frequency until the overload current decreases to prevent the inverter from resulting in overcurrent trip. When the overload current has decreased below stall prevention operation level, this function increases the frequency again. - During constant speed operation: When the output current (output torque during Real sensorless vector control or vector control) of the inverter exceeds the stall prevention operation level (Pr. 22 Stall prevention operation level, etc.), this function reduces frequency until the overload current decreases to prevent the inverter from resulting in overcurrent trip. When the overload current has decreased below stall prevention operation level, this function increases the frequency up to the set value. - During deceleration: When the output current (output torque during Real sensorless vector control or vector control) of the inverter exceeds the stall prevention operation level (Pr. 22 Stall prevention operation level, etc.), this function stops the decrease in frequency until the overload current decreases to prevent the inverter from resulting in overcurrent trip. When the overload current has decreased below stall prevention operation level, this function decreases the frequency again. Check point: - Check that the Pr. 0 Torque boost setting is not too large. - Check that the Pr. 7 Acceleration time and Pr. 8 Deceleration time settings are not too small. - Check that the load is not too heavy. - Are there any failure in peripheral devices? - Check that the Pr. 13 Starting frequency is not too large. - Check the motor for use under overload. - Check that Pr. 22 Stall prevention operation level is appropriate. Solution: - Increase or decrease the Pr. 0 Torque boost value 1% by 1% and check the motor status.146. - Set a larger value in Pr. 7 Acceleration time and Pr. 8 Deceleration time. - Reduce the load weight. - Try Advanced magnetic flux vector control, Real sensorless vector control or vector control. - Change the Pr. 14 Load pattern selection setting. - Set stall prevention operation current in Pr. 22 Stall prevention operation level. (The initial value is 150%.) The acceleration/deceleration time may change. Increase the stall prevention operation level with Pr. 22 Stall prevention operation level, or disable stall prevention with Pr. 156 Stall prevention operation selection. (Use Pr. 156 to set either operation continued or not at OL operation.) |
| oL Stall prevention (overvoltage) |
Cause: During deceleration: - If the regenerative energy of the motor becomes excessive and exceeds the regenerative energy consumption capability, this function stops the decrease in frequency to prevent overvoltage trip. As soon as the regenerative energy has decreased, deceleration resumes. - If the regenerative energy of the motor becomes excessive when regeneration avoidance function is selected (Pr. 882 = 1), this function increases the speed to prevent overvoltage trip. Check point: - Check for sudden speed reduction. - Regeneration avoidance function (Pr. 882 to Pr. 886) is being used? Solution: - The deceleration time may change. Increase the deceleration time using Pr. 8 Deceleration time. |
| PS/P5 PU stop |
Cause: Stop with STOP/RESET button of the PU is set in Pr. 75 Reset
selection/disconnected PU detection/PU stop selection. Check point: - Check for a stop made by pressing STOP/RESET button of the operation panel. Solution: - Turn the start signal OFF and release with PU/EXT button. |
| TH Electronic thermal relay function pre-alarm |
Cause: Appears if the cumulative value of the Pr. 9 Electronic
thermal O/L relay reaches or exceeds 85% of the preset level. If it reaches
100% of the Pr. 9 Electronic thermal O/L relay setting, a motor overload trip
(E. THM) occurs. - The THP signal can be simultaneously output with the [TH] display. For the terminal used for the THP signal output, assign the function by setting "8" (positive logic) or "108" (negative logic) in any of Pr. 190 to Pr. 196 (output terminal function selection). Check point: - Check for large load or sudden acceleration. - Is the Pr. 9 Electronic thermal O/L relay setting is appropriate? Solution: - Reduce the load weight or the number of operation times. - Set an appropriate value in Pr. 9 Electronic thermal O/L relay. |
| MT Maintenance signal output |
Cause: Indicates that the cumulative energization time of the
inverter has reached a given time. When the setting of Pr. 504 Maintenance
timer alarm output set time is the initial value (Pr. 504 =
"9999"), this warning does not occur. Check point: - The Pr. 503 Maintenance timer setting is larger than the Pr. 504 Maintenance timer alarm output set time setting. Solution: - Setting "0" in Pr. 503 Maintenance timer erases the signal. |
| CP Parameter copy |
Cause: Displayed when parameters are copied between the FR-A701
series and FR-A700 series 75K or higher. Check point: - Check that parameters are not copied between the FR-A701 series and FR-A700 series 75K or higher. Solution: - Copy between the same FR-A701 series. |
| SL Speed limit indication (output during speed limit) |
Cause: Output if the speed limit level is exceeded during torque
control. Check point: - Check that the torque command is not larger than required. - Check that the speed limit level is not low. Solution: - Decrease the torque command. - Increase the speed limit level. |
| FN Fan alarm |
Cause: For the inverter that contains a cooling fan, appears on the
operation panel when the cooling fan stops due to a fault or different
operation from the setting of Pr. 244 Cooling fan operation selection. Check point: - Check the cooling fan for a fault. Solution: - Check for fan fault. |
| E.OC1 Overcurrent trip during acceleration |
Cause: When the inverter output current reaches or exceeds
approximately 220% of the rated current during acceleration, the protective
circuit is activated to stop the inverter output. Check point: - Check for sudden acceleration. - Check that the downward acceleration time is not long in vertical lift application. - Check for output short circuit. - Check that the Pr. 3 Base frequency setting is not 60Hz when the motor rated frequency is 50Hz. - Check if the stall prevention operation level is set too high. - Check if the fast-response current limit operation is disabled. - Check that the regeneration is not performed frequently. (Check that the output voltage becomes larger than the V/F reference voltage at regeneration and overcurrent occurs due to the high voltage.) - Check that the power supply for RS-485 terminal is not shorted. (under vector control) - Check that the rotation direction is not switched from forward to reverse rotation (or from reverse to forward) during torque control under Real sensorless vector control. Solutions: - Increase the acceleration time. (Shorten the downward acceleration time in vertical lift application.) - When "E.OC1" is always lit at starting, disconnect the motor once and start the inverter. If "E.OC1" is still lit, contact your sales representative. - Check the wiring to make sure that output short circuit does not occur. - Set the Pr. 3 Base frequency to 50Hz. - Lower the setting of stall prevention operation level. - Activate the fast-response current limit operation. - Set base voltage (rated voltage of the motor, etc.) in Pr. 19 Base frequency voltage. - Check RS-485 terminal connection. (under vector control) - Prevent the motor from switching the rotation direction from forward to reverse (or from reverse to forward) during torque control under Real sensorless vector control. |
| E.OC2 Overcurrent trip during constant speed |
Cause: When the inverter output current reaches or exceeds
approximately 220% of the rated current during constant speed operation, the
protective circuit is activated to stop the inverter output. Check point: - Check for sudden load change. - Check for output short circuit. - Check if the stall prevention operation level is set too high. - Check if the fast-response current limit operation is disabled. - Check that the power supply for RS-485 terminal is not shorted. (under vector control) - Check that the rotation direction is not switched from forward to reverse rotation (or from reverse to forward) during torque control under Real sensorless vector control. Solutions: - Keep load stable. - Check the wiring to make sure that output short circuit does not occur. - Lower the setting of stall prevention operation level. - Activate the fast-response current limit operation. - Check RS-485 terminal connection. (under vector control) - Prevent the motor from switching the rotation direction from forward to reverse (or from reverse to forward) during torque control under Real sensorless vector control. |
| E.OC3
Overcurrent trip during deceleration or stop |
Cause: When the inverter output current reaches or exceeds
approximately 220% of the rated inverter current during deceleration (other
than acceleration or constant speed), the protective circuit is activated to
stop the inverter output. Check point: - Check for sudden speed reduction. - Check for output short circuit. - Check for too fast operation of the motor's mechanical brake. - Check if the stall prevention operation level is set too high. - Check if the fast-response current limit operation is disabled. - Check that the power supply for RS-485 terminal is not shorted. (under vector control) - Check that the rotation direction is not switched from forward to reverse rotation (or from reverse to forward) during torque control under Real sensorless vector control. Solutions: - Increase the deceleration time. - Check the wiring to make sure that output short circuit does not occur. - Check the mechanical brake operation. - Lower the setting of stall prevention operation level. - Activate the fast-response current limit operation. - Check RS-485 terminal connection. (under vector control) - Prevent the motor from switching the rotation direction from forward to reverse (or from reverse to forward) during torque control under Real sensorless vector control. |
| E.OV1 Regenerative overvoltage trip during acceleration |
Cause: If regenerative energy causes the inverter's internal main
circuit DC voltage to reach or exceed the specified value, the protective
circuit is activated to stop the inverter output. The circuit may also be
activated by a surge voltage produced in the power supply system. Check point: - Check for too slow acceleration. (e.g. during descending acceleration in vertical lift load) - Check that the Pr. 22 Stall prevention operation level is not lower than the no load current. Solution: - Decrease the acceleration time. - Use regeneration avoidance function (Pr. 882 to Pr. 886). - Set a value larger than the no load current in Pr. 22 Stall prevention operation level. |
| E.OV2 Regenerative overvoltage trip during constant speed |
Cause: If regenerative energy causes the inverter's internal main
circuit DC voltage to reach or exceed the specified value, the protective
circuit is activated to stop the inverter output. The circuit may also be
activated by a surge voltage produced in the power supply system. Check point: · Check for sudden load change. · Check that the Pr. 22 Stall prevention operation level is not lower than the no load current. Solution: · Keep load stable. · Use regeneration avoidance function (Pr. 882 to Pr. 886). · Use the brake unit or power regeneration common converter (FR-CV) as required. · Set a value larger than the no load current in Pr. 22 Stall prevention operation level. |
| E.OV3 Regenerative overvoltage trip during deceleration or stop |
Cause: If regenerative energy causes the inverter's internal main
circuit DC voltage to reach or exceed the specified value, the protective
circuit is activated to stop the inverter output. The circuit may also be
activated by a surge voltage produced in the power supply system. Check point: - Check for sudden speed reduction. Solution: - Increase the deceleration time. (Set the deceleration time which matches the moment of inertia of the load) - Longer the brake cycle. - Use regeneration avoidance function (Pr. 882 to Pr. 886). - Use the brake unit or power regeneration common converter (FR-CV) as required. |
| E.THT Inverter overload trip (electronic thermal relay function) |
Cause: If a current not less than 150% of the rated output current
flows and overcurrent trip does not occur (220% or less), the electronic
thermal relay activates to stop the inverter output in order to protect the
output transistors. (Overload capacity 150% 60s, inverse-time
characteristic) Check point: - Check that acceleration/deceleration time is not too short. - Check that torque boost setting is not too large (small). - Check that load pattern selection setting is appropriate for the load pattern of the using machine. - Check the motor for use under overload. Solutions: - Increase acceleration/deceleration time. - Adjust the torque boost setting. - Set the load pattern selection setting according to the load pattern of the using machine. - Reduce the load weight. |
| E.THM
Motor overload trip |
Cause: The electronic thermal relay function in the inverter detects
motor overheat due to overload or reduced cooling capability during
constant-speed operation and pre-alarm (TH display) is output when the
integrated value reaches 85% of the Pr. 9 Electronic thermal O/L relay
setting and the protection circuit is activated to stop the inverter output
when the integrated value reaches the specified value. When running a special
motor such as a multi-pole motor or multiple motors, provide a thermal relay
on the inverter output side since such motor(s) cannot be protected by the
electronic thermal relay function. Check point: - Check the motor for use under overload. - Check that the setting of Pr. 71 Applied motor for motor selection is correct. - Check that stall prevention operation setting is correct. Solution: - Reduce the load weight. - For a constant-torque motor, set the constant-torque motor in Pr. 71 Applied motor. - Check that stall prevention operation setting is correct. |
| E.FIN Heatsink overheat |
Cause: If the heatsink overheats, the temperature sensor is actuated
to stop the inverter output. The FIN signal can be output when the
temperature becomes approximately 85% of the heatsink overheat protection
operation temperature. For the terminal used for the FIN signal output,
assign the function by setting "26" (positive logic) or
"126" (negative logic) in any of Pr. 190 to Pr. 196 (output
terminal function selection). Check point: - Check for too high surrounding air temperature. - Check for heatsink clogging. - Check that the cooling fan is stopped. (Check that "Fn" is displayed on the operation panel.) Solution: - Set the surrounding air temperature to within the specifications. - Clean the heatsink. - Replace the cooling fan. |
| E.IPF Instantaneous power failure |
Cause: If a power failure occurs for longer than 15ms (this also
applies to inverter input shut-off), the instantaneous power failure
protective function is activated to trip the inverter in order to prevent the
control circuit from malfunctioning. If a power failure persists for longer
than 100ms, the fault output is not provided, and the inverter restarts if
the start signal is ON upon power restoration. (The inverter continues
operating if an instantaneous power failure is within 15ms.) In some
operating status (load magnitude, acceleration/deceleration time setting,
etc.), overcurrent or other protection may be activated upon power
restoration. - When instantaneous power failure protection is activated, the IPF signal is output. Check point: - Find the cause of instantaneous power failure occurrence. Solution: - Remedy the instantaneous power failure. - Prepare a backup power supply for instantaneous power failure. - Set the function of automatic restart after instantaneous power failure (Pr. 57). |
| E.UVT Undervoltage |
Cause: If the power supply voltage of the inverter decreases, the
control circuit will not perform normal functions. In addition, the motor
torque will be insufficient and/or heat generation will increase. To prevent
this, if the power supply voltage decreases below about 150VAC (300VAC for
the 400V class), this function stops the inverter output. - When a jumper is not connected across P/+ and P1, the undervoltage protective function is activated. - When undervoltage protection is activated, the IPF signal is output. Check point: - Check for start of large-capacity motor. - Check that a jumper or DC reactor is connected across terminals P/+ and P1. Solution: - Check the power supply system equipment such as the power supply. - Connect a jumper or DC reactor across terminals P/+ and P1. |
| E.ILF
Input phase loss |
Cause: This fault is output when function valid setting (= 1) is set
in Pr. 872 Input phase loss protection selection and one phase of the three
phase power input is lost. When the setting of Pr. 872 Input phase loss
protection selection is the initial value (Pr. 872 = "0"), this
fault does not occur. Check point: - Check for a break in the cable for the three-phase power supply input. Solution: - Wire the cables properly. - Repair a break portion in the cable. - Check the Pr. 872 Input phase loss protection selection setting. |
| E.OLT Stall prevention stop |
Cause: If the frequency has fallen to 0.5Hz by stall prevention
operation and remains for 3s, a fault (E.OLT) appears and trips the inverter.
OL appears while stall prevention is being activated. When speed control is
performed by Real sensorless vector control or vector control, a fault
(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 point: - Check the motor for use under overload. - 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.) Solution: - 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 |
Cause: Description 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 point: - Check for an earth (ground) fault in the motor and connection cable. Solution: - Remedy the earth (ground) fault portion. |
| E.LF Output phase loss |
Cause: This function stops the inverter output if one of the three
phases (U, V, W) on the inverter's output side (load side) is lost. Check point: - 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. Solution: - Wire the cables properly. - Check the Pr. 251 Output phase loss protection selection setting. |
| E.OHT External thermal relay operation |
Cause: 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. This function is
available when "7" (OH signal) is set in any of Pr. 178 to Pr. 189
(input terminal function selection). - When the initial value (without OH signal assigned) is set, this protective function is not available. Check point: - 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). Solution: - 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 |
Cause: Stops the inverter output when the motor overheat status is
detected for 10s or more by the external PTC thermistor input connected to
the terminal AU. - This fault is available when "63" is set in Pr. 184 AU terminal function selection and AU/PTC switchover switch is set in PTC side. When the initial value (Pr. 184 = "4") is set, this protective function is not available. Check point: - 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 ? Solution: - Reduce the load weight. |
| E.OPT Option fault |
Cause: - Appears when the AC power supply is connected to the terminal R/L1, S/L2, T/L3 accidentally when a high power factor converter is connected. - Appears when torque command by the plug-in option is selected using Pr. 804 Torque command source selection and no plug-in option is mounted during torque control. - Appears when the switch for the manufacturer setting of the plug-in option is changed. - Appears when a communication option is connected while Pr. 296 = "0 or 100." Check point: - Check that the AC power supply is not connected to the terminal R/L1, S/L2, T/L3 when a high power factor converter (FR-HC, MT-HC) or power regeneration common converter (FR-CV) is connected. - Check that the plug-in option for torque command setting is connected. - Check for the password lock with a setting of Pr. 296 = "0, 100" Solution: - Check the parameter (Pr. 30) setting and wiring. - The inverter may be damaged if the AC power supply is connected to the terminal R/L1, S/L2, T/L3 when a high power factor converter is connected. Please contact your sales representative. - Check for connection of the plug-in option. Check the Pr. 804 Torque command source selection setting. - Return the switch for the manufacturer setting of the plug-in option to the initial status. (Refer to instruction manual of each option) - To apply the password lock when installing a communication option, set Pr.296 ≠ "0,100". |
| E.OP3 Communication option fault |
Cause: Stops the inverter output when a communication line error
occurs in the communication option. Check point: - Check for a wrong option function setting and operation. - Check that the plug-in option is plugged into the connector securely. - Check for a break in the communication cable. - Check that the terminating resistor is fitted properly. Solution: - Check the option function setting, etc. - Connect the plug-in option securely. - Check the connection of communication cable. |
| E. 1
to E. 3 Fault 1 to Fault 3 Option fault |
Cause: Stops the inverter output if a contact fault, etc. of the
connector between the inverter and plug-in option occurs or if a
communication option is fitted to the connector 1 or 2. - Appears when the switch for the manufacturer setting of the plug-in option is changed. Check point: - Check that the plug-in option is plugged into the connector securely. (1 to 3 indicate the option connector numbers.) - Check for excess electrical noises around the inverter. - Check that the communication option is not fitted to the connector 1 or 2. Solution: - Connect the plug-in option securely. - Take measures against noises if there are devices producing excess electrical noises around the inverter. - Fit the communication option to the connector 3. - Return the switch position for the manufacturer setting of the plug-in option to the initial status. |
| E.PE Parameter storage device fault |
Cause: Stops the inverter output if fault occurred in the parameter
stored. (EEPROM failure) Check point: - Check for too many number of parameter write times. Solution: - When performing parameter write frequently for communication purposes, set "1" in Pr. 342 to enable RAM write. Note that powering OFF returns the inverter to the status before RAM write. |
| E.PE2 Parameter storage device fault |
Cause: Stops the inverter output if fault occurred in the parameter
stored. (EEPROM failure) Solution: There is an hardware issue in drive. Need to repair or replace drive. |
| E.PUE PU disconnection |
Cause: - This function stops the inverter output if communication between the inverter and PU is suspended, e.g. the operation panel and parameter unit is disconnected, when "2, 3, 16 or 17" was set in Pr. 75 Reset selection/disconnected PU detection/PU stop selection. - This function stops the inverter output when communication errors occurred consecutively for more than permissible number of retries when a value other than "9999" is set in Pr. 121 Number of PU communication retries during the RS-485 communication with the PU connector. - This function stops the inverter output if communication is broken within the period of time set in Pr. 122 PU communication check time interval during the RS-485 communication with the PU connector. Check point: - Check that the FR-DU07 or parameter unit (FR-PU04/FR-PU07) is connected properly. - Check the Pr. 75 setting. Solution: - Fit the FR-DU07 or parameter unit (FR-PU04/FR-PU07) securely. |
| E.RET Retry count excess |
Cause: If operation cannot be resumed properly within the number of
retries set, this function trips the inverter. This function is available
only when Pr. 67 Number of retries at fault occurrence is set. When the
initial value (Pr. 67 = "0") is set, this fault does not occur. Check point: - Find the cause of alarm occurrence. Solution: - Eliminate the cause of the error preceding this error indication. |
| E. 5 Fault 5 E. 6 Fault 6 E. 7 Fault 7 E.CPU CPU Fault |
Cause: Stops the inverter output if the communication error of the
built-in CPU occurs. Check point: - Check for devices producing excess electrical noises around the inverter. Solution: · Take measures against noises if there are devices producing excess electrical noises around the inverter. · After this same fault comes then there is an hardware issue in drive. Need to repair or replace drive. |
| E.CTE Operation panel power supply short circuit |
Cause: RS-485 terminal power supply short circuit. When the
operation panel power supply (PU connector) is shorted, this function shuts
off the power output and stops the inverter. At this time, the operation
panel (parameter unit) cannot be used and RS-485 communication from the PU
connector cannot be made. When the internal power supply for RS-485 terminals
are shorted, this function shuts off the power output. At this time,
communication from the RS-485 terminals cannot be made. - To reset, enter the RES signal or switch power OFF, then ON again. Check point: - Check for a short circuit in the PU connector cable. - Check that the RS-485 terminals are connected correctly. Solution: - Check the PU and cable. - Check the connection of the RS-485 terminals |
| E.MB1
Fault to E.MB7 Fault |
Cause: Brake sequence fault.
The inverter output is stopped when a sequence error occurs during use
of the brake sequence function (Pr. 278 to Pr. 285). This fault is not
available in the initial status (brake sequence function is invalid). Check point: - Find the cause of alarm occurrence. Solution: - Check the set parameters and perform wiring properly. |
| E.OS
Overspeed occurrence |
Cause: Trips the inverter when the motor speed exceeds the Pr. 374
Overspeed detection level during encoder feedback control Real sensorless
vector control and vector control. This fault is not available in the initial
status. Check point: - Check that the Pr. 374 Overspeed detection level value is correct. - Check that the number of encoder pulses does not differ from the actual number of encoder pulses. Solution: - Set the Pr. 374 Overspeed detection level value correctly. - Set the correct number of encoder pulses in Pr. 369 Number of encoder pulses. |
| E.OSD
Speed deviation excess detection |
Cause: Trips the inverter if the motor speed is increased or
decreased under the influence of the load etc. during vector control with Pr.
285 Excessive speed deviation detection frequency set and cannot be
controlled in accordance with the speed command value. This fault is not
available in the initial status. Check point: - Check that the values of Pr. 285 Excessive speed deviation detection frequency and Pr. 853 Speed deviation time are correct. - Check for sudden load change. - Check that the number of encoder pulses does not differ from the actual number of encoder pulses. Solution: - Set Pr. 285 Excessive speed deviation detection frequency and Pr. 853 Speed deviation time correctly. - Keep load stable. - Set the correct number of encoder pulses in Pr. 369 Number of encoder pulses. |
| E.ECT
Signal loss detection |
Cause: Trips the inverter when the encoder signal is shut off under
orientation control, encoder feedback control or vector control. - This fault is not available in the initial status. Check point: - Check for the encoder signal loss. - Check that the encoder specifications are correct. - Check for a loose connector. - Check that the switch setting of FR-A7AP/FR-A7AL (option) is correct. - Check that the power is supplied to the encoder. Or, check that the power is not supplied to the encoder later than the inverter. - Check that the voltage of the power supplied to the encoder is same as the encoder output voltage. Solution: - Remedy the signal loss. - Use an encoder that meets the specifications. - Make connection securely. - Make a switch setting of FR-A7AP/FR-A7AL (option) correctly. - Supply the power to the encoder. Or supply the power to the encoder at the same time when the power is supplied to the inverter. If the power is supplied to the encoder after the inverter, check that the encoder signal is securely sent and set "0" in Pr. 376. - Make the voltage of the power supplied to the encoder the same as the encoder output voltage. |
| E.OD Excessive position fault |
Cause: Trips the inverter when the difference between the position
command and position feedback exceeds Pr. 427 Excessive level error under
position control. - This fault is not available in the initial status. Check point: - Check that the position detecting encoder mounting orientation matches the parameter. - Check that the load is not large. - Check that the Pr. 427 Excessive level error and Pr. 369 Number of encoder pulses are correct. Solution: - Check the parameters. - Reduce the load weight. - Set the Pr. 427 Excessive level error and Pr. 369 Number of encoder pulses correctly. |
| E.EP Encoder phase fault |
Cause: Trips the inverter when the rotation command of the inverter
differs from the actual motor rotation direction detected from the
encoder. - This fault is not available in the initial status. Check point: - Check for mis-wiring of the encoder cable. - Check for wrong setting of Pr. 359 Encoder rotation direction. Solution: - Perform connection and wiring securely. - Change the Pr. 359 Encoder rotation direction value. |
| E.P24 24VDC power output short circuit |
Cause: When the 24VDC power output from the PC terminal is shorted,
this function shuts off the power output. At this time, all external contact
inputs switch OFF. The inverter cannot be reset by entering the RES signal.
To reset it, use the operation panel or switch power OFF, then ON again. Check point: - Check for a short circuit in the PC terminal output. Solution: - Remedy the earth (ground) fault portion. |
| E.CDO Output current detection value exceeded |
Cause: Trips the inverter when the output current exceeds the
setting of Pr. 150 Output current detection level. - This function is available when Pr. 167 Output current detection operation selection is set to "1". When the initial value (Pr. 167 = "0") is set, this protective function is not available. Check point: - Check the settings of Pr. 150 Output current detection level, Pr. 151 Output current detection signal delay time, Pr. 166 Output current detection signal retention time, Pr. 167 Output current detection operation selection. |
| E.IOH Inrush current limit circuit fault |
Cause: Stops the inverter output when the resistor of inrush current
limit circuit overheated. The inrush current limit circuit failure. Check point: · Check that frequent power ON/OFF is not repeated. · Check that the primary side fuse (5A) in the power supply circuit of the inrush current limit circuit contactor (FR-A740-110K or higher) is not fused. · Check that the power supply circuit of inrush current limit circuit contactor is not damaged. Solution: - Configure a circuit where frequent power ON/OFF is not repeated. - If the problem still persists after taking the above measure then there is an hardware issue in drive. Need to repair or replace drive. |
| E.SER
Communication fault |
Cause: This function stops the inverter output when communication
error occurs consecutively for more than permissible retry count when a value
other than "9999" is set in Pr. 335 RS-485 communication retry
count during RS-485 communication from the RS-485 terminals. This function
also stops the inverter output if communication is broken for the period of
time set in Pr. 336 RS-485 communication check time interval. Check point: - Check the RS-485 terminal wiring. Solution: - Perform wiring of the RS-485 terminals properly. |
| E.AIE Analog input fault |
Cause: Stops the inverter output when a 30mA or higher current or a
7.5V or higher voltage is input to terminal 2 while the current input is
selected by Pr. 73 Analog input selection, or to terminal 4 while the current
input is selected by Pr. 267 Terminal 4 input selection. Check point: - Check the setting of Pr. 73 Analog input selection, Pr. 267 Terminal 4 input selection and voltage/current input switch. Solution: - Either give a frequency command by current input or set Pr. 73 Analog input selection, Pr. 267 Terminal 4 input selection, and voltage/current input switch to voltage input. |
| E.USB USB communication fault |
Cause: When the time set in Pr. 548 USB communication check time
interval has broken, this function stops the inverter output. Check point: - Check the USB communication cable. Solution: - Check the Pr. 548 USB communication check time interval setting. - Check the USB communication cable. - Increase the Pr. 548 USB communication check time interval setting. Or, change the setting to 9999. |
| E.4 Fault 4 Converter overcurrent |
Cause: The current flows in the regeneration converter module
exceeds the specified value, protective circuit activates and stops the
inverter output. Check point: - Check that sudden acceleration/deceleration is not performed. - Check for sudden load change. - Check that wiring is correct. - Check that instantaneous power failure did not occur. - Check that the thyristor load does not exist in the same power supply system. Solution: - Increase acceleration/deceleration time. - Keep load stable. - Wire the cables properly. - When a thyristor load exist in the same power supply system, install an AC reactor (FR-HAL). |
| E.8 Power supply fault |
Cause: - When overvoltage occurs in the converter side during input phase failure detection - When overvoltage occurs in the converter side during instantaneous power failure detection - When fault of power supply frequency is detected - When phase shift is not detected When any of the above conditions applied, it is judged as power supply and the inverter output is stopped. Check point: - Check the power supply and wiring. Solution: - Perform wiring correctly. |
| E.10 Converter transistor protection thermal operation |
Cause: Current flowing in the module of the regeneration converter
is less than the overcurrent shutoff level and exceeds the specified value,
electronic thermal relay activates for protection and the inverter output is
stopped. Check point: - Check the motor for use under overload. (excess regeneration amount) - Check that the thyristor load does not exist in the same power supply system. Solution: - Reduce the load weight. - When a thyristor load exists in the same power supply system, install an AC reactor (FR-HAL). |
| E.11 Opposite rotation deceleration fault |
Cause: The speed may not decelerate during low speed operation if
the rotation direction of the speed command and the estimated speed differ
when the rotation is changing from forward to reverse or from reverse to
forward during torque control under Real sensorless vector control. At this
time, the inverter output is stopped if the rotation direction will not
change, causing overload. This fault is not available in the initial status
(V/F control). (It is available only during Real sensorless vector control.) Check point: - Check that the rotation direction is not switched from forward to reverse rotation (or from reverse to forward) during torque control under Real sensorless vector control. Solution: - Prevent the motor from switching the rotation direction from forward to reverse (or from reverse to forward) during torque control under Real sensorless vector control. - There is an hardware issue in drive. Need to repair or replace drive. |
| E.13 Internal circuit fault |
Cause: Stop the inverter output when an internal circuit fault
occurred. Solution: There is an hardware issue in drive. Need to repair or replace drive. |
| E.15
Converter circuit fault |
Cause: - When a fault occurs in the peripheral circuit of the regeneration converter CPU - When a fault occurs in the control power supply circuit. - When a fault occurs in the inrush current limit circuit. If any of the above conditions applied, it is judged as converter circuit fault and the inverter output is stopped. Check point: - Check for devices producing excess electrical noises around the inverter. Solution: - Take measures against noises if there are devices producing excess electrical noises around the inverter. - There is an hardware issue in drive. Need to repair or replace drive. |
How to Read FR-A701 Faults via Panel & Software
Mitsubishi drives use a unique fault naming convention. In 2026, efficient troubleshooting relies on understanding the operation panel and connecting via modern software:
- FR-DU07 Operation Panel: The standard display provides immediate status.
- E.xxx (Fault): Indicates a hard trip (e.g., E.OC1 for Overcurrent during accel). The drive output stops immediately.
- Alarm History: You can view the last 8 faults by navigating to the “Alarm History” menu. Pressing SET on a specific fault often reveals the voltage and current at the time of the trip.
- FR Configurator2 (PC Software): This is the modern
standard for Mitsubishi drives. Connect your PC via the USB port (if
equipped on the specific model) or the PU connector (RS-485).
- Graph Function: Use the software oscilloscope to trace motor speed vs. torque. This is vital for FR-A701 drives used in hoisting, as it reveals if the load is slipping before the brake engages.
- Life Diagnosis: The A700 series tracks the age of internal capacitors and cooling fans. The software will warn you if the main circuit capacitors are nearing end-of-life (approx. 10 years).
Frequently Asked Questions (FAQ)
Q: What is the difference between an “E.” Code and other codes?
A:
- E.xxx (Fault): A critical failure that trips the drive (e.g., E.OV1 Overvoltage). The reset button must be pressed.
- Warning (e.g., OL, PS): The drive continues to run but is limiting performance. For example, OL (Stall Prevention) means the drive is reducing speed to prevent an overcurrent trip.
Q: How do I reset a Mitsubishi FR-A701 fault?
A:
- Press the STOP/RESET button on the FR-DU07 panel.
- Toggle the RES (Reset) digital input terminal (connect RES to SD for >0.1s).
- Power cycle the drive (wait for the keypad display to vanish completely).
Q: What does “E.OC1” vs “E.OC2” vs “E.OC3” mean?
A: All indicate Overcurrent, but the suffix tells you when it happened:
- E.OC1: During Acceleration (Check for short acceleration time or motor short).
- E.OC2: During Constant Speed (Check for sudden load changes).
- E.OC3: During Deceleration (Check braking resistor or regen circuit).
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