Mitsubishi FR-D700 Inverter (Basic)

A voltage (or current) has been input to terminal 4 when the setting in Pr. 267 Terminal 4 input selection and the physical voltage/current input switch on the inverter are mismatched. This incorrect input configuration can lead to erroneous frequency commands, unstable operation, or potentially damage the analog input circuit if not corrected.

An error has occurred within the inverter's CPU or its peripheral circuits. This is a critical internal hardware fault that can lead to unpredictable operation, improper control, or complete shutdown of the inverter. Electromagnetic interference from nearby devices can sometimes trigger such faults.

The analog input bias and gain calibration values (C3, C4, C6, C7) have been set too close, potentially causing instability, inaccuracy, or an invalid range in analog input readings. This can lead to incorrect frequency commands or control signals, affecting system performance. The inverter output is not shut off.

This fault code signifies a detected malfunction within the inverter's internal safety circuit, specifically indicating an issue related to the CPU's safety monitoring functions. When triggered, it causes the inverter to shut off its output to maintain a safe state and prevent motor operation.

An excessive current condition has been detected while the inverter is accelerating the motor. This can be caused by an abnormally high load, a short circuit between phases, or a ground fault on the inverter's output side, potentially leading to damage if not resolved.

This fault code indicates a detected malfunction within the inverter's internal safety circuit. When active, it causes the inverter to shut off its output to ensure a safe state, preventing drive operation. This is a critical internal error.

The cumulative value of the electronic thermal O/L (overload) relay has reached 85% or higher of the Pr. 9 Electronic thermal O/L relay setting. This warning signifies that the motor or inverter is approaching an overload condition based on its thermal model. Continued operation without reducing the load could lead to an overload trip.

The external thermal relay connected to the OH signal has been activated. This indicates that the motor or connected equipment is experiencing an overload condition, potentially causing damage if not addressed. The inverter will not restart unless it is manually reset after the relay contacts return to normal.

The cooling fan is either at a standstill despite being required to operate, or its speed has decelerated significantly. This indicates a potential failure of the cooling fan, which is critical for dissipating heat from the inverter's internal components. Continued operation without proper cooling will lead to overheating and subsequent damage to the inverter.

The resistor of the inverter's inrush current limit circuit has overheated. This typically occurs due to frequent power cycling (ON/OFF) of the inverter, which causes the inrush current limiting components to work excessively, leading to thermal stress and potential failure. Overheating can degrade or destroy these components, preventing proper inverter startup.

The reset signal (RES signal) is ON, causing the inverter to immediately shut off its output. This indicates that a reset command has been issued, either manually through a control signal or automatically by the system, placing the inverter in a non-operational state.

The cumulative energization time has exceeded the value set in the maintenance output timer (Pr. 503 Maintenance timer). This is a warning indicating that routine scheduled maintenance is due based on operating hours. While not a fault that stops operation, ignoring it can lead to component degradation and potential future failures.

Parameter setting has been attempted in External or NET operation mode when Pr. 77 Parameter write selection is not '2', or when the command source is not the operation panel. This error prevents parameter changes under specific operating mode constraints, aiming to maintain system stability and prevent unintended modifications.

Operation has been attempted while the inverter's operation panel is locked. This is an error message preventing unintended changes or operations, but the inverter output is not shut off. It requires an unlock procedure to regain control of the panel.

The output current has exceeded the detection level set in a parameter. This functions as a protective measure to prevent overcurrent conditions that could damage the motor or the inverter's power components. Incorrect parameter settings can trigger this unnecessarily, or it could indicate an actual motor overload or short circuit condition.

The resistance of the PTC thermistor connected between terminal 2 and terminal 10 has reached or exceeded the Pr. 561 PTC thermistor protection level setting. This indicates an overheating condition, likely in the motor or associated equipment, which could lead to component damage if the load is not reduced.

A communication error has occurred between the PU (Parameter Unit) and the inverter, or the communication interval has exceeded the permissible time during RS-485 communication. This also triggers if the number of communication errors exceeds the retry limit. Loss of communication means the inverter cannot receive commands or send status, interrupting operation.

The 'STOP' button on the operation panel (PU) has been pressed during External operation mode. This warning indicates that the inverter has been commanded to stop via the parameter unit while in an external control mode. The inverter output is not shut off by this warning, but the operation will cease.

An abnormality has occurred in the component (control circuit board) where parameters are stored. This suggests a hardware issue with the inverter's non-volatile memory, potentially leading to incorrect operation, loss of critical settings, or failure to save new parameters. Frequent parameter writes for communication purposes can stress this component.

An attempt has been made to read or write a parameter that is restricted by a password. This security feature prevents unauthorized modification of critical settings, but the inverter output is not shut off. Access to protected parameters is denied until the correct password is entered.

The regenerative brake duty has reached 85% or higher of the Pr. 70 Special regenerative brake duty setting. This warning indicates that the regenerative braking capacity is approaching its limit. If deceleration demands continue to be high without sufficient energy dissipation (e.g., a braking resistor), it could lead to an overvoltage fault.

The inverter has failed to restart within the set number of retries after a preceding error or trip. This indicates a persistent underlying problem that the inverter's automatic recovery attempts could not resolve, requiring manual intervention to prevent further issues.

This alarm indicates that both safety input signals (S1 and S2) are in an open state, which triggers the safety stop function and causes the inverter output to shut off. This typically occurs as an intended safety action or due to a wiring issue, not an internal safety circuit fault.

This fault occurs when the safety circuit input terminals (across S1 and PC, or across S2 and PC) are detected as open. This indicates a break in the safety loop, signaling a potentially unsafe condition and leading to inverter shutdown. It could be due to incorrect wiring, a fault in an external safety device, or an activated safety interlock.

The inverter's safety stop function has been activated, resulting in the immediate shutdown of outputs. This typically indicates that a safety condition has been detected by the system, often an open circuit on the safety input terminals (S1 and SC, S2 and SC), or potentially an internal failure if these inputs are correctly shorted and the drive remains enabled. This is a critical protective action.

The overcurrent stall prevention function has been activated. This warning indicates that the motor is encountering excessive current, possibly due to overload, insufficient acceleration time, improper torque boost settings, or mechanical binding. While a warning, prolonged activation can lead to motor or inverter damage.

The overvoltage stall prevention function has been activated, often during regeneration avoidance operation. This warning indicates that the DC bus voltage is exceeding safe limits, typically due to rapid deceleration or regenerative loads feeding energy back into the inverter. Sustained overvoltage can damage the inverter's internal components.

The voltage at the main circuit power supply has dropped below an acceptable operating level. This can be caused by issues in the incoming power supply line, insufficient capacity, or a fault within the power supply itself, leading to insufficient power for the inverter and potential damage if the voltage fluctuates excessively. The inverter output is shut off.

This error occurs when parameter writing is set to be disabled (via Pr. 77 Parameter write selection), when frequency jump ranges (Pr. 31 to Pr. 36) overlap, or when normal communication between the PU and inverter cannot be established. It prevents new parameter settings from being applied, potentially leading to incorrect operation if desired changes are not accepted.

Parameter writing has been attempted while the inverter is actively operating (STF/STR signal is ON) and Pr. 77 Parameter write selection is not set to '2'. This error prevents parameter changes from being applied while the motor is running, which could cause instability, unsafe conditions, or unexpected behavior if allowed.