Breaker Rating Studies 1

[dcdtn]

Hello, I am interested in learning how other engineers study the ratings of breakers on their systems. Our system has several thousand breakers (all voltage levels), and I am currently in the process of performing a comprehensive breaker duty study on all of them. I am making good progress, but it would be good if there was a tool (software program) available to simplify the task. The program should take into consideration the switchyard configuration, whether the breaker is total-current rated or symmetrical current rated, and should derate oil breakers for reclosing. Does such a software program exist?

Thanks

 

[DanDel]

There are many software packages available for system modeling which take into account C/B ratings. These packages are used to model the system and run studies, such as Short Circuit, Coordination, and Load Flow. This would allow you to keep track of your system, the fault currents available, and whether the C/B ratings are acceptable for their locations. Some are: ETAP (

http://www.etap.com),

EDSA (

http://www.edsa.com),

SKM (

http://www.skm.com).

There are many others you can search for in this forum.

 

[dcdtn]

DanDel,

Thanks for your timely response. We currently have a PSS/E package that we use for most studies (loadflow, stability, short circuit, etc.). It is a good package but has some weaknesses when it comes to breaker duty studies. The packages you mentioned look pretty good, but I believe they would be duplicating a lot of features and capabilities that we already have. I would like something more specific to breaker duty studies and less costly if possible. Do you know of anything like that?

 

[DanDel]

I may not be too clear on your definition of 'breaker duty studies'. Typically, this term is used when referring to the interrupting ratings of the C/B, but you mention you have a program for short circuit studies. Can you be more specific?

 

[jstickley]

DanDel --

PSS/E's short circuit study capabilities provide data on fault current levels, which can be used to determine whether the interrupting capabilities of breakers on the system are sufficient to handle expected fault levels.

dcdtn --

I don't know if you're familiar with PSS/E's IPLAN programming language, but that can be used to extend the capabilities of PSS/E. We've used that language internally to improve our ability to perform loadflow studies more efficiently. I wouldn't be a bit surprised that with a bit of creative programming, you can come up with a way to automate your study.

If that doesn't sound very palatable, I believe that ASPEN's Oneliner package has a breaker rating module. I haven't used this feature (we just purchased the package recently, not specifically for this purpose), so I can't vouch for it's ease of use, but if it's like the rest of the package, it should be pretty good.

Of course there are other packages from other vendors available as well.

 

[dcdtn]

The PSS/E program that we have has the capability for simluating various kinds of faults and providing whichever fault currents and voltages that you need. However, it does not store any information about the breaker itself and therefore cannot tell whether a breaker is overstressed. I am having to manually merge fault current data from PSSE with breaker data that is contained in another database to determine whether breakers are overstressed. It would be nice if there were a program that could do this automatically.

 

[dcdtn]

jstickley -

We do use IPLAN extensively for loadflow and stability studies, but the type of program I am looking for is more than I would want to attempt on my own. Ideally the program would consider breaker type, the standard active when it was made, bus configurations, and deration for reclosing for oil breakers.

 

[jstickley]

dcdtn --

I don't blame you one bit. I should have read your initial post a little more carefully -- once I did, I quickly realized that what you are looking for is quite a bit more than IPLAN could do by itself.

You could probably output data from PSS/E using IPLAN in a manner such that it could be imported to a database of some sort, but to get what you're looking for you'd then have to add all your breaker information to the database, program the database to use the data, etc. -- an awful big project if you ask me (although not impossible). No need to re-invent the wheel of course, if there are other software packages that already do those things, especially if they're cost-effective.

 

[DanDel]

dcdtn, OK, I understand now. I use ETAP, which does this quite nicely. There is an almost complete database of devices from which you can pick out whatever C/B you have. The database contains the fault current ratings for each type of C/B, fused or non-fused, and the rated frame sizes(in amps), which I usually change to the actual trip rating. If your device is not in the database, you can enter it manually. There are also fields which you can enter for all kinds of data, like installation date, maintenance schedules, etc.
When you run a short circuit study, the results contain a column for the sym. fault current, and the adjusted sym. fault current, which uses a multiplier based on the type of C/B you have to give you the actual fault current which corresponds to the manufacturer's rating. There is a column which lists the C/B fault current rating, and then another column which uses an asterisk to flag if the rating is below the calculated fault current. It will also flag a device which is marginal; you can set whether you want this flag for 90% rating, or 95%, or whatever. I thought most software packages provided the same type of flexibility and usefulness.

 

[jbartos]

Suggestion: Visit

http://www.aspeninc.com/bkrpaper.pdf

etc. for more info related to this topic

 

[dcdtn]

DanDel - Thanks, I will look into ETAP a little more. I have a feeling, though, that it might be a little pricey for what I am needing it for.

jbartos - I have that article from when it was published in IEEE Computer Applicaions in Power in January 2002. If I recall, the authors made their own C++ based program that accomplishes what I need. But there was no mention of where to purchase or obtain the program.

 

[jstickley]

dcdtn --

I looked into Aspen's breaker rating module a little further. It is an extension of Aspen Oneliner that must be purchased separately, which explains why I couldn't find it on the version of Oneliner that we use.

The following link describes Oneliner and talks about the breaker rating package a little more.

http://www.aspeninc.com/onel.htm

As I've said, Aspen's short-circuit / relay coordination package (Oneliner) is a software package that we've been quite happy with. If you're interested in finding out more about it, I'd encourage you to contact them -- I'm certain they'll be happy to set up a demo of the program for you.

Of course, you'll want to keep your options open and consider other vendors as well. I'm not familiar with ETAP, EDSA, or SKM, but I would imagine that these other packages mentioned by DanDel will also perform the function you're looking for adequately. In addition to those, you might consider CAPE, although I'm not certain it has a breaker rating module (

http://ic.net/~eii/main.htm).

 

[DanDel]

dcdtn, is there any way you can directly import your short circuit data to your database from your PSS/E software?