FAT : zero sequence impedance measurement test

[Robert2025]

Hello
For a Star delta transformer YNd11, zero sequence impedance measurement test is relevant? I mean when no neutral point exists in Delta, how the test is done?

 

[RRaghunath]

It is relevant only if there is source on Delta side.

Hello
For a Star delta transformer YNd11, zero sequence impedance measurement test is relevant? I mean when no neutral point exists in Delta, how the test is done?

 

[Kiribanda]

For a YNd11 3-limb core transformer the zero seq. impedance is,
1) Between 0.7 to 1.0 of the positive seq. impedance when measured from the Y side.
2) Infinity when measured from the delta side.

The test is performed at the Y side by connecting to a single phase source. This is a standard test.