Warning / Self-diagnosis Detection Function
When the inverter detects a warning, the keypad displays a warning code (flashing).
Note: The fault contact output does not energize on a warning, and the inverter continues operation.
When the warning is no longer active, the keypad will return to its original state.
When the inverter detects a programming error (for example, two parameters contradict each other or are set to an invalid setting), the keypad displays a self-diagnostic code.
Note: The fault contact output does not energize on a self-diagnostic error. While a self-diagnostic code is active, the inverter does not accept a run command until the programming error is corrected.
Note: When a warning or self-diagnostic error is active, the warning or error code will flash on the keypad.
Refer to Table 10.3.1 for an overview, cause, and corrective action for inverter warnings and self-diagnostic errors.

OV (flashing): Overvoltage
    Cause: DC bus voltage exceeds the OV detection level (410Vdc for 200V class, 820Vdc for 400V class; for 440V class, if input voltage 01-14 is set lower than 400V, the OV detection value is decreased to 700Vdc). Possible reasons include too short deceleration time causing regenerative energy to flow back from the motor to the inverter, excessively high inverter input voltage, use of power factor correction capacitors, excessive braking load, defective braking transistor or resistor, or incorrectly set speed search parameters.
    Corrective Action: Increase deceleration time, reduce input voltage to comply with requirements or install an AC line reactor to lower the input voltage, remove power factor correction capacitors, use a dynamic braking unit, replace the braking transistor or resistor, and adjust speed search parameters.

UV (flashing): Undervoltage
    Cause: DC bus voltage is lower than the UV detection level (190Vdc for 200V class, 380Vdc for 400V class; the detection value can be adjusted by 07-13) or the pre-charge contactor is not active while the inverter is running. Possible reasons include too low input voltage, input phase loss, input voltage fluctuation, damaged magnetic contactor, or incorrect DC bus voltage feedback signal value.
    Corrective Action: Check the input voltage, input wiring, and power source, replace the magnetic contactor, and replace the control board or the complete inverter.

OH1: Heat Sink Overheating
    Cause: The temperature of the heat sink is too high. If a heat sink overheating fault has occurred three times in five minutes, it is required to wait for 10 minutes before resetting the fault. Possible reasons include too high ambient temperature, a stopped cooling fan, or a carrier frequency setting that is too high.
    Corrective Action: Check the ambient temperature of the inverter, check the fan or dust and dirt in the heat sink, and check the carrier frequency setting.

OH2 (Inverter Overheating Warning): This warning is triggered when a multifunction digital input set to overheat warning is active. Causes include an active multifunction digital input overheat warning or an incorrectly set multi-function input function. The solution is to check the wiring.

OT (Over Torque Detection): This error occurs when the inverter output torque is higher than the set level for a specified time. Causes include a heavy load. Solutions include checking the over torque detection parameters and reducing the motor load or checking the operation duty cycle.

UT (Under Torque Detection): This error occurs when the inverter output torque is lower than the set level for a specified time. Causes can include a sudden drop in load or a belt break. Solutions include checking the under torque detection parameters and checking the load or application.

bb1, bb2, bb3, bb4, bb5 (External Baseblock): These errors occur when an external base block is active on the respective terminal (S1, S2, S3, S4, S5). Causes include an active multifunction digital input external base block or an incorrectly set multi-function input function. The solution is to check the wiring.

OL2 (Motor Overload): This error occurs when the internal motor overload protection is tripped. It is active when the protection curve parameter 08-05 is set to a value ending in xxx1. Possible causes include a voltage setting in V/F mode that is too high, resulting in over-excitation of the motor, incorrect setting of the motor rated current (parameter 02-01), or a heavy load. Solutions include checking the V/f curve, checking and correcting the motor rated current setting, and checking and reducing the motor load or operation duty cycle.

Inverter Overload: This error occurs when the inverter thermal overload protection is tripped. If an inverter overload occurs four times in five minutes, a four-minute wait is required before resetting the fault. Causes can include a voltage setting in V/F mode that is too high, resulting in over-excitation of the motor, an inverter rating that is too small, or a heavy load. Solutions include checking the V/f curve, replacing the inverter with a larger rating, and checking and reducing the motor load or operation duty cycle.

CE (Communication Error): This error occurs when no Modbus communication is received for 2 seconds and is active when parameter 09-07 is set to 3. Possible causes include a lost connection or a broken wire, or the host computer/software has stopped communicating. Solutions include checking the connection and checking the host computer/software.

CF00 and CF01 (Operator Communication Error 1 and 2): These error codes indicate errors in data transmission between the LCD keypad and the inverter. CF00 occurs when the LCD keypad and inverter cannot transmit data after power on for 5 seconds, while CF01 occurs when data transmission errors persist for more than 2 seconds. To troubleshoot, disconnect the operator and then reconnect, and consider replacing the control board if the issue persists.

CT Fault: This error code indicates a fault in the voltage level of the three-phase input, which can be caused by abnormal input voltage, excessive noise, or a malfunctioning control board. To fix this, check the input voltage signal and the voltage on the control board.

CF20 Double Communication Error: This error code indicates that redundant Profibus and Modbus protocols are being used simultaneously. To resolve this, ensure that only one communication mechanism is used.