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Over Load Relay


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Dear All,


We are designing a star delta starter for 45KW motor. There are two methods for connecting the over load relay in the starter;

(1)At mains after MCCB.

(2) After main contactor where 1/1.73 percent current flows.

Which method is better?


"Don't assume any thing, always check/ask and clear yourself".

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It doesn't matter as long as you calculate the rating correctly. After the MCCB, 100% of FLA. After the main contactor, 58% of FLA. Convention is to put it after the main contactor, so if you think your maintenance people would expect to find it there, it may be better to do that.
"He's not dead, he's just pinin' for the fjords!"
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