Lack of relay engineers 1

[521AB]

One friend of mine on day told me... "do you know why I am replacing all my electromechanical and static relays with the numerical ones?" I answered: "the old ones are broken and you don't get the spare parts, maybe?"
He said "no, no, the old relays are working perfectly. That's not the problem".
"So whay then?", I asked...
"I loose the young engineers if I ask them to take care of plants with old technology. After some months they say 'thank you very much, I go somewhere else, where I can use what I studied for..':"

Ok, I have "painted" it a little bit, but this was the main meaning of the discussion anyway. What is your opinion on that?

 

[toiap]

I am stuck somewhere in the middle - not too young, not too old. From my perspective, I believe having an understanding of the EM relays provides a solid basis for understanding the system. You cannot agrue the physics of an EM relay. I have too often seen someone think they have a thorough understanding of the system because they can set a digital relay, only to find out that their understanding is not quite so good.

Also, at 3 AM when the line or generator trips many old school engineers or techs can have the problem identified with EM relays and event recorder data before a young engineer can connect to the relay and download the data.

As in the old Karate Kid movie, wax on/wax off may have seemed boring and unrelated to karate but in the end it all made sense. The same goes for EM relays and power systems.

 

[lz5pl]

Nice discussion, sorry that I missed it. Last days I was on site testing of (numerical of course!) generator protection. All functions in one not very big box. Including vector diagrams via Web interface. Everything was well until the moment when after energizing we read Idiff=0.08In and Irestr=0.19In. Many additional measurements were done, vector diagrams were analized and finally we enter the cell under the Gen to find that starpoint CT's were wrongly identified and we have cyclic phase transposition in secondary circuits! (Please don't blame me - I am only relay protection subcontractor for this project!!!). Morale: Good secondary circuits technician is invaluable in commissioning works. Numerical technology is something nice (although for me is a bit boring to read 500+ pages Manual of O/C protection), but as slavagar mentioned, most of problems are usually related to wiring or other simple thinks.

521AB described specific of numerical technology very well (as usual in his posts!) as a protection panel in one box. This is very close to my favorite joke with computer guys that for me the laptop is just a HiTech screwdriver, because using it I connect various functions like in the past we connected various relays to complete the protection scheme. You should see the face of our SysAdmin !

Regards,
LZ5PL, 24 years 1 day as commissioning engineer and control & protection designer.

http://www.triel.bg

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

 

[wbd]

ScottyUK,

Thanks for the drawings. They look very similiar to full size dwgs I have here of systems still in use. I have also referred to a 1923 edition of the Electrical Engineer's Handbook that came with my office for info on some devices still in use.

 

[lz5pl]

ScottyUK, thank you for nice schematics! Two years ago I had to connect two new feeders into similar BB protection installed by Chinese 30+ years ago on 110 kV s/s in Albania. It was really an exciting job !

I like to collect old schematics, especially of tube radios, but also from my professional field.

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

 

[Eleceng01]

I want to commment on this as well - as a fairly new young engineer. I started my career designing and testing micro-processor relays for a relay manufacturer. I now work in the consulting industry with a senior protection engineer.

Anyone who bored by the EMs should reconsider. If you look at how our predacestors did things and the cool ideas that they had - one will only be amazed. The new relays only immulate the old EMs.

I have been exposed to both and I love them both for theier features and 'lack of features.' Just think, no one can hack into a EM and tell it to trip remotely (in todays world a definite possiblility with new relays).

I only hope to gain the knowledge of the older protection engineers before they are all gone - they have kept indutry and the utilities going for years! Thank you all!!

 

[521AB]

Eleceng01 and all of you.
It is not true that numerical relays "emulate" EM relays. They did it before, but not now, propably because of generation change. We have designers that are thinking in z transform directly -read samples- instead of thinking in s transform (read linear differential equations, or sometimes just phasors) and converting their s-results in z results.

The task of the protection relay is to trip when there is a fault in the protected area, and not to trip if there is a fault, but not in the protected area. Of course it is also not to trip if there is no fault, but this is easy and obvious.
So, the relay must perform a sort of "pattern recognition", and has a very little time available to do that. Knowledge of power systems in faulted situations is today just the minimum background to design a relay,

Today the digital relay lives in the digital world, and not in one "digitalized analog world". Everything is open to the progress.

 

[Eleceng01]

521AB and all,

I guess I should have chosen my wording more correctly - 521AB is right. I was just trying to point out that understanding the old EMs will help in thinking about the new relays.

 

[521AB]

Eleceng01,
don't worry how you choose your wording...
This is a very interesting discussion and I think that we will flat it down if we think too much about our wordings. I din't want to say that I was right or that you are wrong, even if I said it ( ).
You are very valuable in this forum, as you are a "young protection engineer", and I think we all need persons like you. Not only we "old" engineers, but also the society.

I am completely in agreement with you when you say that understanding EM relays helps. Definitely it helps, but today there is almost no connection between one busbar differential relay with diodes, auxiliary circuits, coils, transistors etc and one fully numerical busbur relay.
The principle: "water in must be equal to water out", is the only thing they have in common (so far they still have the trip contact, but later this will also vanish and will be replaced by a GOOSE message).

Anyway: welcome!