Differential Protection for MV Motors : Comparison of methods

The target of the paper is to present the different methods used to ensure differential protection for MV motors. This protection function is mostly used to protect induction and synchronous motors against phase-to-phase faults. In the event of such faults, the quick response of the differential element may limit the damage that may have otherwise occurred to the motor.The different methods are presented together with the environment (lay-out, impact on motor design, sensors to be supplied...). A case study is presented, the stability and accuracy of each solution is illustrated by simulations.Settings calculation and overall design are addressed. Advantages and drawbacks are presented considering implementation and design.