Trying to find a company to evaluate our generator. 2

[justatech]

Hello all

I've got white marks on the end turns on one of our generators. I think it may be corona. It is a Brush BDAX 7-290ERJT, 71176 KVA. We have been going through Brush for the last week, had a rep from them out for the last couple days and no answers. I think the white marks are an issue and want a second opinion.

So does anyone know of a company that that can take a look at our generator in California? And hopefully do repairs as neccesary.

Thanks all.

 

[Motorwinder]

http://www.visaliaelectric.com/

 

[rmw]

Is the first initial of his first name "J" or "H"?

rmw

 

[justatech]

"H"

 

[rmw]

This is getting intriguing. I will have to call "J" and see if I can find out why "H" was there on Brush's behalf. Until I find out more, I'd prefer not to say more about "H" at this time other than to say that he knows his stuff and I trust his judgement completely. The mystery to me is why he was the one who came out.

I will say that if I had your problem, he would be one of my first choices to call.

rmw

 

[justatech]

"H" happened to be near by (Southern CA). I trusted him, he was hamstringed by his agreement with Brush. I guess the insulation engineer in England did not see the issues he did. We asked him if he'd come back independently, but he would not. He didnt want to ruin his working arrangement with Brush.

We may call him back for future generator issues though.

 

[rmw]

OK, I can see that you completely know who he is and who he is with, and yes, he does (or as of the last time I spoke with him did) have a relationship that he would need to be careful to protect.

I almost recommended him (his firm) to you when I made the recommendation above, but thought that he might be too far away from your location for you to consider so I didn't. Ironic that you encountered him anyway. He is a solid individual.

The firm that I did recommend would be his competitor.

I am a little surprised by Brush's approach. Is the Insulation Engineer you refer to named "H" too, the same name with that first letter; second name begins with "L"? If so, he pretty well knows his stuff, but remember that he is a factory guy and as such has a different view of things than someone like "H" who does nothing but fix-em day in and day out.

rmw

 

[justatech]

The 'H' here was very frustrated that he could not get 'H' there to see what we were seeing here. He was taking it as a failure on his part to show them what we saw here. We sent them about 2 dozen boroscope pictures showing patches of white on the windings. They still said we didnt have a problem, but the rotor needed to be pulled out and cleaned. Then quoted us $200,000 to pull rotor and clean!

 

[rmw]

Let me get this straight. They are saying that pulling the rotor and cleaning it will cure white stuff on the stator end windings????? When I read your words several posts back "...pull the rotor and clean it" I read it several times and thought it meant 'pull the rotor and clean "it" the deposits or white stuff' with the rotor out of the way.

Your last post made it clear that it is the rotor that they are recommending be removed and cleaned. Is it dirty or oily?

I'll come do it for 200K. (see tongue in cheek.) You would be well on your way to buying a new one at that price.

rmw

 

[justatech]

It is oily. We were told thats not an issue for this insulation. The quote is just for pulling the rotor and a general cleaning of the machine. All competitive quotes, since we are a municipality, were between 60,000 to 80,000. Which include insulation repair. I dont think Brush will back on site.

My manager and I considered doing it for $200,000.

 

[ScottyUK]

Oil dripping form the dolls eyes isn't an uncommon 'feature' of the BDAX machines. We were in the process of renewing the shaft oil seals with a modified design when I left the station. Check the ventilation hoses to the chamber between the inner and outer generator end plates. If the plenum pressure is wrong due to air leaks then it contributes to the oil problem. the hoses weren't particularly robust on our version.


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If we learn from our mistakes I'm getting a great education!

 

[electricpete]

what do you mean by "the dolls eyes"?

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(2B)+(2B)' ?

 

[rmw]

I'll let Scotty answer to make sure he is referring to the same thing but I remember the first time I heard the term and especially with a thick english accent, it sounded like "does eyes" (the thing you aim your rifle at) to me.

The reason I won't answer is that I have seen oil dripping from so much of the entire endwinding area that I hardly noticed any on the dolls eyes. And... I actually don't know what the piece is called in USA English.

Justatech, depending on the driver, oil leakage can be caused by problems with the vent mist elimination system as well. One particular popular model uses a filter that will cause the generator bearings to puke oil oint the endwindings if it is not serviced regularly. Based on the generator model you quoted in the OP, it is highly likely that you have one of these.

rmw

 

[ScottyUK]

ePete,

It's the funnel-shaped region of the endwinding outside the stator core. Viewed end-on from a distance the endwinding has a vaguely woven appearance, with a hole in the middle where the rotor would sit. I guess that's where the name comes from. Interested to know if rmw's recollection is the same - it's a phrase I've picked up along the way and have never seen it referred to in a text.



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If we learn from our mistakes I'm getting a great education!

 

[rmw]

Let's see if I can do this. Remember that this is from a ME who only knows how to cut things with a torch and weld it with a stinger and whack it with a hammer.

In the end winding area, the end windings are tied to (non conducting - bakelite?) braces with string (cord, twine) and the string is tied through those brackets and braces with holes in them. There are 4-6 (been a while) large flat brackets that are attached to the end of the stator that stick out axially from end of the frame which are shaped at an angle that follows the angle of the winding as it leaves the stator. That bracket has a row of holes in it into which is threaded the twine that is wrapped around the end windings to bind them to the bracket. The holes in those brackets and the other various pieces like it to which various parts of tne end windings are secured are referred to as the "dolls eyes".

That is why I didn't quite understand your use of it with respect to the oil dripping, as the oil drippings I had seem were all over the end windings not limited to just the bracketry with the dolls eyes.

I don't know if that is a Brush term or an industry term, but I suspect it is the former.

It does blow my mind as a ME that a machine as powerful as a generator would be held together by string and tape. We certainly don't build the turbines that drive them that way.

rmw

 

[rmw]

Here it is:

rmw

 

[rmw]

Or here:

I can't remember if one of these last two posts are the "dolls eyes" or both, but one is for sure.

String.....?????

rmw

 

[BigMac2011]

We can do Corona Inspections and repairs, we provide world wide services. We are based out of San Diego,CA.

http://www.qinetiq-na.com

 

[justatech]

Thanks all for the info.

Looks like we are going with Electrical Maintenance Consultants (EMC) out of Rocklin, CA. They've done a lot of work with the other small municipal utilities in the area.

I've added all the other companies info to a list we have going around here.

Thanks again