The MV CTs can be supplied with round or rectangle window in the center. This provides easy installation for customer as they can use their primary cable or bus bar through the CT ID. Usually these CTs come with equi-potential shield around the ID surface. This equi-potential screen is attached with a pig tail (lead with connector) which comes out of the ID surface. This arrangement allows uniform distribution of charge (non-concentrated) around the surface which further ensures that the CTs withstand high current and high voltage environment in long term use. 