Capacitive Voltage Transformer

Capacitive Voltage Transformer step down extra high voltage signals & provide a low voltage signal for measurement or to operate a protective relay.it consist of two capacitor w/c the transmission line signal is split and an iductive element to tune the device to the line frequency.

CVT and VT are both use for measuring. But CVT is more complicated and can be use to actuate the protective relays during presence of high transient voltage on the transmission line.

it consist of two capacitor w/c the transmission line signal is split and an iductive element to tune the device to the line frequency.

Can you please elloborate what does the above statement.

The surges are suppressed by the inductive PT so the relays may not trip in acse of these.

In case of Line is used for communication too, then CVT is used - since the communication signal can be more efficiently filtered and picked by it.

The cost and the additional equipments and protections required limit the use of CVT (except in EHV lines where the cost may be justified)

CVTs are especially prone to malfunction due to ferroresonance and complicated circuits are required to avoid/ eliminate effect of FR.

CVT itself also acts as a liighning/ surge filter.

thank you but with reference to second para,

In case of Line is used for communication too, then CVT is used - since the communication signal can be more efficiently filtered and picked by it.

Question:then what is the use of wave trap?

Yes! Definitely! It serves reduction of voltage as well as a Line Trap for communication.