Answer / arun

Selection of CT for protection is majorly depends on the
burden limit and Kneepoint voltage at which the core of the
CT gets saturated,after which it cannot produce the
tripping emf in its core.

So check the burden of CT and kneepoint voltage.

Answer / ranga

because protection CTS are rated for high currents than the
metering CTS, so we should not use metering CTs for
protection purpose.

Answer / felixraj

the only diff is the knee point voltage
in metering CT this value is very low, because of this
during fault condition the ct get saturated and o/p almost zero
(metering equipments are protected from fault surge)

protection miss leads in metering CT (it may fails or
nuisance tripping)

Answer / mohammad

Metering and protection CTs have different accurecy class
level as metering CT has 1 class level and for protection
itis represented by 5P,10P etc..

Answer / mohsen khoshsefat

Introduction to Protection Transformers
Protective Current Transformers are designed to measure the
actual currents in power systems and to produce
proportional currents in their secondary windings which are
isolated from the main power circuit. These replica
currents are used as inputs to protective relays which will
automatically isolate part of a power circuit In the event
of an abnormal or fault condition therein, yet permit other
parts of the plant to continue in operation.

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