what is the functioning of cvt in a substation?

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what is the functioning of cvt in a substation?..

Answer / zan

A capacitor voltage transformer (CVT), or capacitance
coupled voltage transformer (CCVT) is a transformer used in
power systems to step down extra high voltage signals and
provide a low voltage signal, for measurement or to operate
a protective relay. In its most basic form the device
consists of three parts: two capacitors across which the
transmission line signal is split, an inductive element to
tune the device to the line frequency, and a transformer to
isolate and further step down the voltage for the
instrumentation or protective relay. The device has at
least four terminals: a terminal for connection to the high
voltage signal, a ground terminal, and two secondary
terminals which connect to the instrumentation or
protective relay. CVTs are typically single-phase devices
used for measuring voltages in excess of one hundred
kilovolts where the use of voltage transformers would be
uneconomical. In practice, capacitor C1 is often
constructed as a stack of smaller capacitors connected in
series. This provides a large voltage drop across C1 and a
relatively small voltage drop across C2.
The CVT is also useful in communication systems. CVTs in
combination with wave traps are used for filtering high
frequency communication signals from power frequency. This
forms a carrier communication network throughout the
transmission network.