ㆍWhen controlling the motor by inverters, if the operation frequency of motor is faster than the output frequency of inverter, as the motor is operated by the generator, the revitalized energy occurs. 

ㆍOver voltage trip occurs as DC link voltage of inverters increases.

ㆍAs DBU series monitor DC link voltage of inverters at all times, if it increases over specific voltage, the energy is consumed by the resistance attached at the outside of DB unit and DC link voltage of inverters is maintained evenly.