The importance of Capacitive voltage transformer (CVT)

Capacitive voltage transformer (CVT) is a kind of voltage transformer that makes use of a capacitive voltage divider and transformer to radically change excessive voltage degree to decrease voltage degree that is appropriate for measuring and safety purposes. The predominant gain of CVT over different voltage transformers is its excessive accuracy and precision in measuring voltage levels. CVT is broadly used in strength transmission and distribution networks as it affords dependable and correct voltage measurements to guard energy tools against harm and decorate the normal community performance.In EHV national grid networks of utilities, CVTs are commonly used for both protection and communication purposes.CVT serves the purpose of a Potential Transformer and Coupling Capacitor.

For voltages above 100KV, the conventional type of PT becomes extremely expensive due to insulation

requirements. Capacitor voltage transformer is a combination of a capacitor potential divider and a magnetic potential transformer, known as an intermediate transformer of a relatively small ratio.

A stack of high voltage capacitors forms the potential divider, capacitance of two sections being C1 and C2 respectively, Z is burden.

The Intermediate transformer's primary voltage is usually above 10 Kv.

The Intermediate transformer consists of an inductance L, which may consist of wholly or partly leakage inductance of its winding.

Value of L is adjusted to 1/ w2( C1+C2) so that vol drop due to current from divider is compensated. So transformation ratio is independent of burden.

The Overall ratio is a product of the divider and transformer ratio.

The accuracy of CVT is an indispensable issue when it comes to voltage dimension as it at once impacts the reliability of strength systems. To make sure the accuracy of CVT, the essential elements that have an effect on the accuracy of CVT are the voltage ratio and section displacement between the fundamental and secondary voltage. To acquire excessive accuracy, these elements need to be decided precisely at some stage in the manufacturing process. Moreover, normal calibration and renovation of CVT are fundamental to preserve its accuracy over time.