we all know that in transformer, voltage and current are
inversely related i.e. Vp/Vs= Is/Ip....so in standard
CT..we have a ratio of 200/5...that means our voltage
should increase by ratio of 40..althoug that is not the
case...because that requires high insulation level.and
pratically not feasible......can anybody clarify my
ques.......thanx
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Answer / k.prakashchandra
Voltage ratio is not applicable when the secondary of the Tr
is short circuited.Actually the secondary of CT has more
turns than the primary.No voltage is applied to primary of
CT and a small voltage is induced in secondary due to the
mmf created in primary by the current flowing through
it.When this emf of secondary is short circuited , the
current produced is proportional to the current in the
primary.That is why it is called CT and not just Tr.
Is This Answer Correct ? | 3 Yes | 2 No |
Answer / peter b
Current and voltage and still inversely related in a CT.
However, the primary of a CT does not see the full line
Voltage i.e. a CT on a 110kV bus does not have a primary
Voltage of 110kV! The CT's primary is in series with the
main load; the primary voltage of the CT is simply the
induced Voltage due to the AC flowing through the primary.
This Voltage is only a tiny fraction of the full line
Voltage. The only insulation requirement is that the CT as
a whole be insulated from neutral/earth. That's why they
are mounted on long insulators.
Is This Answer Correct ? | 0 Yes | 0 No |
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