Distance Relaying

[WDB]

I am trying to apply a distance relay for Zone 3 (reverse direction) on a ring bus and have two breakered lines in the reverse direction with different impedances. What would be some philosophies in providing proper relaying? Would one relay for the higher impedance, the lower impedance or a compromise?

 

[jnims]

Try posting this question on on the newgroup

sci.engr.electrical.sys-protection

There are several engineers that frequent that newgroup with this type of experience.

 

[peterb]

For effective system backup protection, you would have to set the relay to overreach the longest line. Note that in setting the relay you will have to account for local bus infeeds for a remote end fault.
Philosophy here would really depend on the overall line protection scheme. For example, if the lines have duplicate protection, you could probably achieve the desired system backup protection function with a breaker failure scheme.

 

[jghrist]

sci.engr.electrical.sys-protection is a newsgroup that is accessible from a newsgroup reader. If you use Microsoft Outlook 2000 for e-mail, select View/GoTo/News from the menu to get to the Outlook Newsreader. Click Subscribe to Newsgroups and select sci.engr.electrical.sys-protection.

 

[busbar]

For a quick view try the link

http://groups.google.com/groups?hl=en&lr=&ie=UTF-8&group=sci.engr.electrical.sys-protection

Unfortunately at times there are a lot of off-topic posts there. sci.engr.electrical.sys-protection charter id located at

http://www.tva.gov/progroup/seesuse/result.txt

It is a newsgroup; not a new group. Usenet has been part of the internet for quite a few years. s.e.e.s-p was formed in 1996.

 

[RRaghunath]

wdb,

Zone 3 is being set in reverse direction - what is the distance protection scheme being adopted. Is it Blocking scheme or permissive scheme. If it is permissive scheme, is it overreach scheme with weak infeed logic (POR with weak infeed logic).

The Zone 3 reverse reach is set to cover the shortest line in the reverse direction, normally and used to send blocking signal to the relay to the remote end of the protected line to inform that the fault is not in the subject line section. This is in case of blocking scheme. The reverse looking Z3 is used in the weak infeed logic in case of POR scheme. The non-operation of the Z3 is considered same as fault within the protected line section (since there is no source or weak source at that end).

Hope you find the answer you are looking for, above. In case you are interested in more details, you may download distance relay P441 Technical Guide from Alstom website. This has detailed explanations with block diagrams for various distance protection schemes.

 

[jstickley]

This is not directed at anyone in particular -- I just had to get on my soapbox and say a couple things real quick:

Be sure to check the date of posts when replying. I'm sure WDB has his (or her) answer to the zone 3 question by now (posted 7/24/01).

Also, the question of access to the newsgroup is better suited to its own thread to help avoid this kind of confusion.

Please see FAQ731-376 for other posting guidelines.

(and yes, I am in violation of these by posting this here)