Vibration Magnitude Analysis on Induction Motors of Different Efficiency Classes Due to Voltage Unbalance

Small efficiency improvement in induction motors (IMs) often lead to large monetary savings over time. These monetary savings justify the current movement toward the use of higher efficiency IMs. In many cases, replacing a standard efficiency IM with a higher efficiency one is transparent to the user. In other cases, however, there are side effects which need to be considered. This paper presents data showing that vibrations due to voltage unbalance are significantly more pronounced on higher efficiency IMs than in standard efficiency ones. This paper presents the mathematical expressions for active power for an IM under voltage unbalance. Then the paper describes a dynamic simulation framework to validate the paper's hypothesis over a wide range of IMs and a laboratory the test setup used to validate the mathematical expressions with experimental results of standard (IE1), premium (IE3) and super premium (IE4) IMs. Finally, the paper presents vibration measurements due voltage unbalance, and compares the results with the measured vibration levels with the ISO 20816-1 standard vibration severity guidelines.