Answer Posted / ashok bhatnagar

CTs are used for the measurement of high currents as a
primary sensor. The output of the CT is normally connected
to the relevant ammeter which has very low impendence and
secondary remains almost short circuited. The secondary
current has no control over primary current in a CT. If
secondary is open circuited two things will happen :
1. Due to absence of secondary current no counter magnetic
field is produced and flux in core of CT rises to
saturation level which can change the charateristics of CT
and damage it permanently
2. since number of turns in secondary is very high (1:
1000) for , a very high voltage may be induced in secondary
that can harm the prsons working on the instruments panel.

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