why is CCVT Cheaper than VT

[musabeh]

I have a question which I think I already have the answer for it but I need to confirm that.
the question is Why is that CCVT is more Economical Approach in HV Substation design than Traditional PT??

My answer is because in CCVT we use less Winding ( Copper)
is that right?

thank in advance.

 

[Kdanijel]

Hello, Musabeh.
Your answer is partially correct. Difference is in copper for primary and secondary winding as well as magnetic core, oil quantity and insulator diameter.
However, Capacitor Voltage Transformer (CVT, or you can call it CCVT if it is at the same time used as Coupling Capacitor), is an Economical approach only at higher voltage level.
For example, at 110 kV Capacitor voltage transformer has approximately same weight as inductive voltage transformer, and price level is about the same.
Difference in price, as well as unit weight, becomes significant with increase of the voltage level.

In recent years there is a trend in Europe, which is gradually removing CVTs from use even in highest voltage levels on measurement points in system.
Reason is superior accuracy performance of inductive type voltage transformers compared to CVTs, which becomes important for accuracy class 0,2 used for revenue metering (especially at stations where energy metering between two power companies/countries is performed).