Answer / lim

Inductive VT use conventional magnetic material for
coupling of HV and LV circuit. This method has problems due
to insulation of EHV circuit to the magnetic core(usually
at ground potential) and very expensive to produce as it
may need a few step down stages to achieve to final voltage
ratio, each stage shall be floated at gradually reduced
voltage relative to ground potential.
CVT is design to resolve this cost issue. The voltage is
first step down to relatively low level using capacitor
divider and connect to normal IVT for further reduction in
voltage to final value.

Answer / sudipta

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 wound primary 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.

Answer / parveen

in inductive t/f,voltage lead the current but capacitive
t/f, current lead the voltage.

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