A novel design and development of a microprocessor-based current protection relay

This paper describes a novel design of an electrical protection relay using microprocessor; which can be used to protect electrical equipment during various fault conditions. A range of protection schemes have been introduced; such as current unbalance protection; IDMT earth fault protection; IDMT over-current protection; instantaneous earth fault protection; instantaneous over-current protection; and thermal overload protection. Various advanced functions like event recording, run-hour alarm, keypad data entry, display of absolute value of running currents etc. are incorporated.