Ct testing wye-delta 1

[Needhelp-pls]

Question here... so I am testing ct's on a wye-delta power transformer.. 138kv-69kv-12kv
Im testing high side bushing ct's
Test leads are hooked up black on H1 and red on HOXO.
I had a 44 percent error in my readings and after I shunted lowside (X) bushings together my error went away and results were good
Why does shunting the X-side together make a difference in test results in making the error go away ? Thx for any help

 

[davidbeach]

It allows the current to flow.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[Needhelp-pls]

Could you please elaborate?

 

[davidbeach]

Current only flows in one side of a transformer winding if it can also flow on the other side. Without the shunt you were trying to force everything through the magnetizing branch of the transformer and that doesn't work well.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[Needhelp-pls]

Thank you !! Appreciate it