Answer / iamdon

CT is used mainly for Instrumentation(Measurement and
protection system) purposes that is why it is also termed as
instrument transformer.The measuring and protecting devices
are not rated to sustain high currents.What a CT does is,
it lowers the current in secondary side so that measurement
as well protection can be done at a reduced level of
current.

The digit in CT ratio of secondary side is IS standard for
rated secondary current so that uniformity among manufactures
be established.
The various values of secondary currents are
1)in the range of 0-5 amp e.g, 1A,5A
2)in the order of mA(particularly 40mA)in case of digital
devices for measurements and protection.

Author:arbelectbit@yahoo.com

Answer / k.prakashchandra

With introduction of electronic protection and
metering ,nowadays 1A secondary CTs are employed.

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