12-11-2014, 12:21 PM
Abstracts: The Star/Delta starter is generally manufactured from three contactors; an electromechanicaltimer and a thermal overload for operating a 3 phase motor at 440 volt at ac mains supply 50 Hz.The interlocking arrangement of all the contactor coils is traditionally wired in 440 volt ac. However in our project we have taken up the same to operate a 3 phase motor at 440 volt ac mains supply 50 Hz with a set of 12 volt DC relays, an electronically adjustable timer and a set of miniature circuit breakers. The interlocking arrangement of the relay coils and the electronic timer are all wired in low voltage dc of 12 volt fed from an inbuilt dc power supply for safe handling of the starter during the study, still retaining it is application for a 3 phase motor starting with single phasing prevention