Hi everyone,

In AC motor drive systems, especially in Variable Frequency Drives (VFD), an OV (Over Voltage) high voltage error occurs when the DC link (or DC bus) voltage rises above a permissible limit. This kind of fault typically arises during braking or sudden reductions in load, which can result in energy feeding back into the VFD.

Causes of an OV fault can include:

    Rapid Braking: If the motor is brought to a stop rapidly, energy produced by the motor can feed back into the VFD, causing an increase in the DC link voltage. In such cases, using a braking resistor to dissipate the regenerative energy can be a solution.

    High Grid Voltage: If the supply voltage is excessively high, this can also lead to an elevated DC link voltage.

    Poor Filtering: Inadequate filtering or an inappropriate capacitor at the VFD's output can lead to energy feedback.

    Incorrect Parameter Settings: If the VFD's parameters are set incorrectly, this can also lead to an OV fault.

    Degraded Capacitors: It's possible for the DC link capacitors within the VFD to age or become faulty. In such cases, the capacitors might not store energy effectively, leading to an OV fault.

When an OV fault occurs, the drive typically shuts down automatically to ensure safety. To prevent such faults, system design, parameter settings, and maintenance procedures should be correctly implemented. Moreover, if an OV fault is encountered, it's crucial to determine its cause and apply appropriate corrective measures.