Transient Inrush Current in High-Efficiency and Standard Motors

A study was made of motor transient inrush current as a function of steady-state locked current and power factor. A simplified formula is given to predict peak transient inrush values, and the method is supported by test data. This subject is important since modern protection systems detect transient currents electronically. There is an increasing need among standards organizations and users to be able to calculate transient conditions from steady-state parameters. An initial attempt is made to provide this facility.