# Multi Ratio Current Transformers

I encountered a problem in measuring electrical energy using a multi ratio current transformer (CT). The catalogue of CTs is unavailable.

I have little information about the type of CT I am using. I have several questions about this matter. Firstly, the CT I work with has 7 connections: X7,100,200,300,400,500&600.

The connection for ratio 100/5 was on X7 & 100. Something that is confusing me is that X7 a common connector and if connection X7 to 100 measures 100/5, are other windings from 200 to 600 in circuit or open? If they are in circuit how does it produce a 100/5 ratio, and if they are open how it that possible for a CT?

Secondly, the power transformer has delta connections and the CT connection is a Star. After I have connected the meter to the CT I get an error in energy metering. Is it possible that this error is due to the star connection of the CT and should it be a delta connection, as for the power transformer?

Its impossible to change the CT connection to delta. Can I define any coefficient factor to remove this error with out changing the circuits?

The power transformer ratio is 14400/3300, with a delta connection and the CT's ratio is 200/5, with star connection.