Aspects of overcurrent protection for feeders and motors

Abstract

This paper discusses the coordination of the characteristics and the backup and redundancy possible with microprocessor relays. The paper reviews the application of negative sequence overcurrent characteristics for unbalanced protection in motors and also covers the rules for coordination of negative sequence characteristics to provide sensitive phase to phase protection in feeders. The paper also covers reset characteristics and the requirements for stator and rotor thermal protection of induction motors.<>