On the secondary side of a distribution transformer, we use
1c x 630 sq mm cable. Why dont we use 4 core cables instead
of 1 core cables on the secondary. Why we use aluminium
cable glands on the outgoing instead of brass cable glands?

Answer Posted / pp

As the Transformer size increases the current flowing
through LT also increases. For Transformers of 630 kVA and
above, single core cables are used for LT as the insulation
is not sufficient enough to carry large amount of current
at source (T/F Secondary)for poly core cables and leads to
phase to phase faults.

Note: current for cable at Secondary termination is larger
than at any point due to creation of multiple circuits.

Poly core cables are available in sizes upto 300 sq.mmm.
for LT .

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