Tx zero sequence

[BJ-Elect]

Hi,
For a standard Dy11 11/0.4kV UK Distribution Tx, with neutral solid earth.
What is the typical value for the zero sequence impedance Z0?.
Is it generally taken aws 1 x Pos sequence?.
links to standards/docs/literature etc. appreciated.
Any help appreciated.
Regards,
BJ

 

[7anoter4]

See ABB Switchgear Manual Edition 11-chapter 3 Calculation of Short-Circuit Currents in Three Phase System Table 39.

 

[davidbeach]

Absent zero sequence test data, for a 3-phase core type transformer assuming R0=R1 and X0=0.85*X1 seems to give reasonable results. For shell type transformers and banks of three 1-phase transformers assume Z0=Z1.

When one this sentence into the German to translate wanted, would one the fact exploit, that the word order and the punctuation already with the German conventions agree.

-- Douglas Hofstadter, Jan 1982

 

[prc]

Please refer to IEC 60076-8 Application Guide for Power Transformers.

 

[BJ-Elect]

All,
many thanks for the replies.

 

[7anoter4]

It is very interesting, indeed, prc. Mainly in- IEC 60076-8 - chapter 4 Zero-sequence properties – neutral load current and earth fault conditions, magnetic saturation, and inrush current. However, there is no useful data for a calculation.

 

[prc]

Table 1 of the standard gives constants to calculate zero sequence impedance for various transformer connections

 

[cuky2000]

X0=0.85*X1 are reasonable results only for Dy connections