bus zone protection basics

[rainfire]

hello, can someone please advise the basics of bus zone protection on 11kV 3ph AC switchgear?

As far as I understand a CT on the bus riser (next to bus coupler) for an O/C relay is sufficient. is this correct?

 

[ScottyUK]

Check out some of the online references in the Protection subsection of faq238-1287. The Areva NPAG is very good: Chapter 15 is specific to busbar protection, but you would undoubtedly benefit from reading from the beginning. The North American texts are also good. All the references contain more than enough information to answer your question far better than we could hope to here without the aid of diagrams.


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Sometimes I only open my mouth to swap feet...

 

[liming]

basicly,it is a differential protection. You need to have a check zone to prevent the muloperation on the through fault.

 

[lz5pl]

If there are no special requirements for conventional type of BB protection, you could use one based on reverse interlocking principle. It is described in AREVA book - NRAG and in almost any Manual for numerical overcurrent relay. This is very good cost-effective solution for MV switchgear. I have seen it realized even using GOOSE messages (but all your relays must have 61850 interface, of course).

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It may be like this in theory and practice, but in real life it is completely different.
The favourite sentence of my army sergeant

 

[RRaghunath]

Rainfire,

When you say 'CT in the buscoupler panel is sufficient' I guess you are talking of Partial diffrential protection that is widely used as an inexpensive bus zone protection for medium voltage switchgears. I agree with you and think that the arrangement is very effective for the money it costs.