Induction Motor Timer Using Auto Delta Star Starter

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The proposed project aims at providing low voltage to induction motors through star to delta conversion. Star Delta is basically used to lower the current rate applied to motor at start and after that full load current is applied.
The project uses a set of relays that helps in shifting the motor connections from star to delta along with a time delay and six lamps in place of 3 phase motors where a single phase motor is represented by two lamps. In star mode, a system is used that starts a 3 phase motor at 440V AC mains supply 50Hz with a set of 12V DC relays and in delta mode, this is electronically adjusted with a timer.
At starting, i.e. in star mode, the lamps would glow dim and in delta mode operated by timer it will glow with full intensity. This indicates that the supply voltage in star mode was 440 roots of 3 whereas in delta there was full voltage supply of 440V. The timer consists of a 555 in mono-stable mode, and its output is fed to relay so that the mains supply gets changed from 3 phase star to delta.

Induction motor timer

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