ST300 Series | E9 – What does this message mean, and what can be done?

If the error message E9 appears on the frequency converter display, it indicates an overvoltage during constant speed operation.

Causes:
• Disturbance in the input voltage.
• Strong energy feedback.
• Missing braking resistor.
• Integrated braking unit is not activated.
• Overvoltage protection is not enabled.
• The inverter is in standby mode and the mains supply comes from a poorly regulated generator that supplies too high a voltage under no-load conditions.

Solutions:
Check the power supply.
Check whether an external torque is acting on the motor.
Connect a braking resistor.
Check the settings of function codes P08.37 and P08.38.
Check the settings of function codes P11.03 and P11.04.
If the error occurs in standby mode, check the input voltage and the setting of function code P11.02.
Ensure the braking resistor is not overloaded during continuous operation, and adjust the braking voltage threshold P08.38 if necessary.

If none of these causes apply, please contact technical support.

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