My new book - any thoughts? 4

[Skogsgurra]

This is a very general electronic, electricity and automation question.

I have in my fourty+ years as a commissioning engineer, trouble-shooter and designer with ABB, Siemens and own company found that there are a few very common mistakes that account for a vast majority of all problems in automation and drive systems.

I am going to sit down in southern France (Camargue) for a couple of months and compile 30 - 40 dominant causes for unexpected problems and badly functioning systems. It will be about inrush currents that takes out fuses/breakers and cause short contact life, unnecessary high band-width that makes systems unreliable, cooling and why it - contrary to popular belief - is good to have. There will be eternal but forgotten truths about many other things like bearing currents (that will be a long chapter), DC motor operation and thyristor drives and I will mostly use stuff that I have collected during field work. Each subject will get a two - seven pages (A4 - a little less than legal - format) treatment with four or five pages being typical.

I am, however, sure I will miss out a few important topics, I have, after all, not seen all problems (I think).

So, if you have any unusual, interesting or plain stupid things that you think should be included in the book, please add a few sentences here. Or e-mail me. Also, if anyone in southern France would like to have a Pastis with me, just say so. I could use some divertissement... (I do speak French, so language is not a problem. Especially not after a few 51 ).

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[dpc]

Grounding in general seems to generate a lot of field issues. Both for power and instrumentation/control. If you could sort out the factual from the anecdotal myths, that would be a great service.

Also, some recommended troubleshooting techniques and methods - no one learns this in school.

 

[DRWeig]

Gunnar, I'm not sure if you were involved but there was a thread in here (that I can't find) about an excavation site in which the power supply was inadequate to start a third shovel when two were online. The solution was to raise the two online buckets and let them fall in order to generate a bit more power for the third shovel's start-up.

I thought that was a wonderful trick...

Best to you,

Goober Dave

Haven't see the forum policies? Do so now: Forum Policies

 

[Skogsgurra]

Great comments trickling in!

I have thought about some type of structured "tree" to help in systematic trouble-shooting. And there are inputs that help me doing that.

And, I think that I shall include little factoids/ancedotes like Dave's falling buckets. That will make for lighter and more interesting reading. More such stuff!

Gunnar Englund

http://www.gke.org

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Half full - Half empty? I don't mind. It's what in it that counts.

 

[davidbeach]

That tail of falling buckets couldn't have come from anybody other than waross. I do have a vague memory of it. Bill??

 

[waross]

Back in the seventies I worked on a the erection of a large dragline at the Syncrude project.
Some stats:
Mass; about 7000 tons
Power: 12,000 HP. 4 MG sets. Each set comprised of a 3000 HP motor driving three 1050 HP DC generators and two 1300 HP generators. Weight of each MG set, about 80 tons.
Working radius: 360 feet.
Height of boom above grade: 214 feet.
Length of boom 400 feet.
Drag bucket: about 75 or 80 cubic yards.
Power supply: 12,000 Volt trailing cable.
Watching the meters when this was working, the draw would be about 7 MW when the bucket was being lifted. Dropping the empty bucket would regenerate about 2 MW.

We had ample power to start the machine. We had an adviser from Bucyrus-Erie on-site. While sharing a coffee break, he told us of the technique that was used in strip mines with a soft power supply of using the regenerated power from the dropping buckets of several machines to ease the starting surge of an incoming machine.

This machine is now out of service and on display beside highway 63 near The Syncrude base plant.

http://farm1.static.flickr.com/87/225535786_51a81623a9_m.jpg

http://media.jrn.com/images/oilsands-21-oilsands-syncrude-at-dusk.jpg

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[Skogsgurra]

Bill - of course!

That is a wonderful story! The 'puter paralyzed need to hear such things! I guess there is even som math they can do on this. The pictures, the way out and the math. That is something the youngsters will love.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

Some may notice that we still have over 5700 HP of generators on a 3000 HP motor.
The operating cycle was such that the generators were never simultaneously loaded to their maximum capacity.

The generators had Babbitt bearings lubricated with oil rings. There was no turning gear. Once running these machines typically run 24/7 indefinitely. During test and commissioning, each night, we had to manually "roll" each set until the oil rings had brought enough oil up so that the set turned freely. We started them with two men on a seven foot hook wrench on a coupling and two more to reposition the wrench each time it was lifted for another bite. We usually had four to six men working together to roll each of the four sets. When four men could keep the set turning easily by pushing on the ends of the armature windings we were ready to go DOL and then move on to the next set.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[KllrWolf]

My ideas are less about the technical aspects than as a book. If it can/ment be used as a reference I would say make sure it has a good table of contents, a good index, and at least a basic definitions section. I have several different reference books that have great information, but they lack in the above items, making it very difficult to locate the information.

 

[Skogsgurra]

Great! I had been thinking of a TOC. But it is easy to include an index also. And the definitions part - I made one for SKF a long, long time ago. Perhaps time to refresh it.

http://www.google.se/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&ved=0CC8QFjAA&url=http://

http://www.gke.org/rapporter/files/...0sGRwJ7Bv5P3Trg&bvm=bv.51773540,d.bGE&cad=rja

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[Skogsgurra]

OOPS - that's the wrong version! It contains spelling errors and also a numerical error. So don't pay too much attention to it. Of course, a definitions section would be nice. But that would be either monstrous or incomplete. So, I think that I will add 'intratextual' definitions where needed. The index could then be used to look those definitions up.

Remember, it will not be a text-book on automation. There are many good ones already. The book will cover things that never get mentioned in text-books, but still will meet the engineer once he is 'on the loose'.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[KllrWolf]

The book is sounding awesome. The inline definitions with index would work well. I may not deal with automation as a job, but I do need to know those kinds of things to help our customers. I am definitely interested in getting it once you finish it.

 

[Skogsgurra]

BTW, the book will be in Swedish. At least initially. So it may not be very useful to the engineering community in a broader meaning.

Gunnar Englund

http://www.gke.org

--------------------------------------
Half full - Half empty? I don't mind. It's what in it that counts.

 

[waross]

I answered a call to a small crane with the complaint that the hoist brake would not release.
The brake coil was controlled by a relay similar (but not identical) to this:

http://www.cesco.com/b2c/product/224599

The machine had been in service for several years but for some reason the relay did not interrupt the current. The brake coil was a fairly high resistance and the current was quite low but it set up an arc across each break of the double break contacts. The heat was just enough to melt the silver alloy contact material. The molten material then flowed together in such a way as to bridge the contacts. Once there was a metallic path and no arc the metal cooled and left the contacts welded together by two miniature hour glasses of silver alloy.


Bill
--------------------
"Why not the best?"
Jimmy Carter