why C T secondary are rating 5A generaly .

Answer Posted / sobhuza, za

5A CTs are used beacuse they are cheaper than 1A Cts for
the same primary rating.I mean 600/1A CT is more expensive
than 600/5A CTs as more turns are in the former. 5A CTs
also imply that under full load conditions, 5A is flowing
between the CTs and the relays. Therefore there will be a
large volt-drop if the CTs are far away from the relays.
This is the reason why it 5A CTs are used for indoor
switchgear. Recall that the indoor switchgear houses the
relays as well so the CTs and the relays are closer to one
another. Therefore you will note that 5A CTs are not used
for outdoor CTs.

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