Cable Size for Star Delta Staring Motor

No.

I can't answer your cable size exactly, we have different standards, let alone different dimensions and units of measure. But here, you are allowed to use 58% of the motor FLC rating for sizing each of the 6 conductors on a wye (star)-delta starter. That is because in wye, the current will be 58% of normal through both sets of conductors, then in Delta it will split evenly but if the conductors were sized at 50%, it would be too small for the Star connection.

Please consult your local electrician who can offer and install a safe solution for you.

In India, anything is possible, but apart from being undersized to start with, the length of the cable run and method of enclosure would also be a deciding factor.

Not sure that 6mm² Al would be rated at 50 amp even over there, other than maybe as an open aerial conductor, and that's a small cable for an aerial

Go through catalog of reputed manufacturers like Telemecanique etc who gives not only cable sizes but also fuse/cb, oc relay,contactors sizes too.For cable sizing you need to consider de-rating factors like enclosure,grouping etc too.

Dear Mr. Anupam Diwan,

The normal full load current for 37 KW Motor, will be approx. for 70 Amps, where as you have mentioned as 64 Amps. O.K.,

The Starting Current will be about 3 to 4 times for few seconds, and gradually reduce and changes to delta, again a small kick load experienced where the current may exceed 70 Amps level and current will reach below 64-70 Amps Level.

For any cable the de-rating factor will have to be duly considered, Hence 6 Sq.MM Al. Cable cannot handle this current.

DHAYANANDHAN.S

Which national installation standard are you intending to use, Mildred?

Cable from cb to starter should carry FLC while that from starter to motor carries only 58% of FLC.Apply derating factors & select a cable(1c or 3c).

"Please guide me thanks"

Consult the millions of wire sizing tables available at the IHS;

Reference Library

Otherwise, Go directly to jail. Do not pass go, do not collect $200.00.

To understand more about cable selection, pls check out here http://www.psa-outline.com/cable-selection/

British Standard 7671.

If in doubt, consult a qualified local Electrician.