10-04-2017, 08:40 PM
A capacitor voltage transformer (CVT or CCVT), is a transformer used in power systems to step down extra high voltage signals and provide a low voltage signal, for metering or operating a protective relay.
With the popularisation of PCs, the constant voltage transformers (CVTs) have also become equally popular. The CVT is simply a magnetic transformer of a special construction that has a capacitor connected across the secondary winding of the transformer. In an ordinary transformer, the primary and secondary windings are wound near each other so that whenever there is a change of voltage across the primary there is a corresponding change in the secondary voltage depending upon the ratio of the turns on the two windings. However, in a CVT the primary and secondary windings are wound separately from each other, as illustrated in figure. To set up field in between the coils, a separate shunt path is provided between the two windings but an airgap is formed in the shunt path. A capacitor is connected across suitable tappings of the secondary winding. The constructional details of a CVT are shown in the figure.
