Substation IED's 2

[Dumbo2929]

Does anyone have a link to a good history in "simple" english of the move from electro-mechanical meters and relays to substation IED's and solid-state protection? I'm trying to convince someone on replacing 30+ year old meters & relays with some new technology that can communicate and feed into an energy management/SCADA system.
I'm looking for a white paper on the benefits of this "new" technology in substation applications. Thanks.

 

[tinfoil]

There's a lot of information (and a lot of self-promotion of products) at

http://www.selinc.com/techpprs.htm

 

[jnims]

There is a paper from the Petroleum and Chemical Industry Conference that may be useful:

"Do you want to put all your 'Relay Eggs' in one Basket?"

Paper No. PCIC-98-22

You can purchase it through IEEE Explore.

 

[davidbeach]

To me, the significant advantages of numeric relays over electromechanical relays:

* Numeric relays do not rely on physical mechanisms for sensing and operation.

* Numeric relays do not have jeweled bearings to maintain or contacts to burnish.

* Numeric relays impose a much smaller burden on CT circuits, resulting in more accurate measurement.

* Numeric relays can provide functions and combinations of functions not readily available in electromechanical relays, negative sequence being a prime example.

* Numeric relays provide sequence of event reporting.

* Numeric relays provide oscillographic records of fault events.

* Numeric relays also have communications and metering.

 

[Dumbo2929]

I agree with the benefits on digital relays versus older mechcanical relays. I was trying to find a white paper or brief narrative decribing the technology of these relays (and IED meters) and the advantages over mechanical devices, to teach a non-technical person.

 

[RalphChristie]

Maybe this can help a bit....

http://www.areva-td.com/servlet/Con...uct_Detail&c=AGF_Product&cid=1089880316992&am

p;rid=&lid=en&pid=1017999014820&tab=Chapters&id=1056536208254

(Copy and paste whole address)

Download chapter 7, Relay Technology.


[red]Failure seldom stops us, it is the fear for failure that stops us - Jack Lemmon[/red]

Make the best use of Eng-Tips.com
Read the Site Policies at FAQ731-376

 

[Bung]

I'm not sure I would be too quick to write off e-m relays. They do have advantages - longevity, especially in some hostile environments for starters. Electronic relays just don't seem to last as long - we've still got PBO and similar relays dating back to the early '50s that are still going strong, and we are already replacing some electronic relays after only 15 or 20 years service. It's a case of being prepared to accept the trade-off of lower maintenance costs, much improved functionality and short life of electronic relays against the long life, simplicity and independence from computers of e-m.

Training, setting, installation and commissioning are also factors to consider vis-a-vis the skill sets of the people doing the work. The young guns with no instrument repair skills may struggle with e-m, but may be happy using a computer to drive everything. Older people with an instrument fitter type of background may be better off with e-m and avoiding the computers. Horses for courses.

Some of the problems we have had with numeric realys have had me wondering sometimes if they are all they're cracked up to be. But then, they have proved themselves very useful on occasions.

My perfect relay - a CDG with built in fault waveform recorder!


Bung
Life is non-linear...

 

[Dumbo2929]

Bung, I agree E-M relays are simple and have a long life, if properly maintained. In my application we are going to replace meters and relays with electronic to allow remote access to data in a mini-SCADA HMI application.

 

[edison123]

Ralphchristie,

That was an excellent link.