Answer / jayaram

suppose the motor is more than 5hp, two contractors,one
timer, two push buttons(no and nc)and one 230v relay is
required.because of star-delta starting.
but motor is below 5hp one over load relay,one contractor
and two push buttons(no and nc) is suffcient

Answer / mohd azharuddin

It depends on type of starting methods u r opting, for example u can use DOL METHOD which requires one overload protection relay, one contactor, two push buttons, one nc and one no elements but the disadvantage of this method is high inrush current so this method shoudnt be used for big motors


Another method is STAR DELTA METHOD in which u require one overload protection, three contactors, one for main, second for star, third for delta, one timer with relay logic, two push buttons, one no and nc elements, in this method motor is started in star connection for the first few seconds and then changeover to delta, by using this method we can reduce high inrush current.

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