Design & Development of Electromechanical Release For Multiple Higher Current Rating of MCCB

Abstract

This project is divide into two parts, first one deals with the realization of elec- tromechanical release system for 800A rating molded case circuit breaker (MCCB) and the second part includes the concept development, prototype testing and de- sign verification of of electromechanical release system for 1000A & 1250A MCCB which includes two units, one is overload protection trip unit and the other is short-circuit trip unit. This project includes realization of electromechanical release system of MCCB with 800 A current rating. To realize, a simulation of a prototype has been carried out using creo software. The simulation reveals interference problems during assembly if any. Tolerance stack-up studies and design verification was carried out before development of the actual prototype. The prototype was tested and design failure mode and effect analysis (DFMEA) technique was used to rectify the faults found during the testing. This project also includes conceptual design of electromechanical release sys- tem for MCCB of higher current ratings of 1000A & 1250A. This is an effective alternative of microprocessor release system with the help of both electrical as well as mechanical concepts. Electromechanical release consist of a bimetallic strip to sense the overload of current and an electromagnet to sense short-circuit condition.