Understanding AS2067 Earthing Requirements: A Closer Look at Figure B5 and B4

[victorgoh1981]

I have a question about the earthing requirement in AS2067. Figure B5 and B4 show that the Earth cables from the HV substation should connect to the Earth bar of the remote transformer. Since the HV substation is far away from the remote transformer, we do not need to equalize the potential. why do we need to connect the Earth between them? The Earth conductor could transfer the EPR (Earth Potential Rise) from the HV substation to the transformer location in the event of an Earth fault. That could create a dangerous situation for the people near to transformer. Could anyone help me to answer this question? Thanks

 

[berkeman]

What country are you in? What is your interest in this question? Are you studying to take an advancde electrician certification exam?

 

[anorlunda]

He's talking about Australian Standard® Substations and high voltage installations exceeding 1 kV a.c. , https://www.saiglobal.com/PDFTemp/Previews/OSH/AS/AS2000/2000/2067-2008.pdf

But the majority of the document is behind a paywall.

 

[Baluncore]

... Since the HV substation is far away from the remote transformer, ...

Maybe that is a false assumption.
The earthing may be required only when they are co-located.
With the paywall it is difficult to examine the exact text.

 

[Babadag]

I have not a copy of this Australian Standard but as it noted in the Preface it is based on IEC 61936 which is included now in EN 50522/2010.

In this standard at item 6 Measure to avoid transferred potential you may know how to proceed to avoid potential transfer from high to low voltage system or to communication.

 

[Babadag]

From the attached sketch you can see that if the shield of the medium voltage cable is grounded [earthed] only at one end at the ungrounded end the potential will be A, but if it grounded at both ends the potential will be B. We can do so that B could be less than maximum permissible.