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Posted By: iwire Fan Cooled? Who asked for it? - 09/16/06 06:45 PM
Here are some photos of a transformer I am doing.

It is a GE 500 KVA 480-208Y/120 Transformer.

We did not ask for fan cooling or shunt trip molded case switches or high temp alarms, none of the cut sheets I received showed any of this.

There are temp sensors in each coil, if the temp rises the fans come on, more heat brings on an audible alarm and finally if it keeps getting hotter the shunt trip switches open.

GE says it's a benefit as the footprint is much smaller, the reality IMO is that the fans and switches cost less than using more raw material to produce a 500 KVA that does not need forced cooling.

[Linked Image]

[Linked Image]

You can click on the rest of the pictures to get a larger one, be warned the large photos are large files.

<IMG SRC=\"https://www.electrical-contractor.net/forum/iw/300KVA1SM.jpg\">

<IMG SRC=\"https://www.electrical-contractor.net/forum/iw/300KVA3SM.jpg\">

<IMG SRC=\"https://www.electrical-contractor.net/forum/iw/300KVA4SM.jpg\">

<IMG SRC=\"https://www.electrical-contractor.net/forum/iw/300KVA2SM.jpg\">

I would be happy to hear any comments, good bad or otherwise.

The job is yet to be inspected.

Bob



[This message has been edited by iwire (edited 09-16-2006).]
Posted By: Tesla Re: Fan Cooled? Who asked for it? - 09/16/06 07:08 PM
The install looks terrific.

I'm with GE: this design reduces hysterisis losses since the core is smaller and the reduced footprint is an advantage all the way around.

At this scale forced convection is the way to go.

The shunt trip thermal protection is terrific. It means that you don't have to get complicated when over the 112.5 kVA threshhold.

Now if only the contract permitted compact aluminum feeders instead of copper....

Then you wouldn't have needed a wire bender.
Posted By: iwire Re: Fan Cooled? Who asked for it? - 09/16/06 07:20 PM
First, thank you for the kind words.

Wow this is cool I get to bend the ear of a GE guy.

Do you mind if I speak candidly about this?

Quote
Then you wouldn't have needed a wire bender

That is my primary complaint, there is darn little space for the number of conductors needed. I could not find enough space to enter all my conduits.

In the end the wireways worked well but they add work and expense and basically mean the footprint is increased back to 'normal' dimensions.

Second complaint, we have now made what was essentially a maintenance free unit into a unit that will need maintenance.

I see this as being handy for remodels when space is tight but I would rather have a maintenance free unit if space allows.

Just an opinion from a guy stuck trying to fit 600 lbs of copper into a shoe box. [Linked Image]
Posted By: caselec Re: Fan Cooled? Who asked for it? - 09/16/06 07:34 PM
Hi Bob

A few months ago I posted a comment on the MH site about GE transformers with fans. I was really surprised to see them when I pulled the front cover. Unfortunately I had stubbed the primary and secondary raceways up in the slab to enter the bottom of the transformer. This wasn’t going to work! Luckily this was only an issue for on of the 4 transformers on the project. My supplier had these transformers shipped directly from GE to the job site but they were willing to have MGM ship be a replacement and put the GE in their stock.

I talked to an engineer from MGM and was told that GE was using the fans to get the TP1 rating. He said that they opted to use a higher grade steel core for their tp1 units instead of fans. I’m not sold on the idea of using fans. You now have 6 fan motors that will eventually fail.

I also don’t care for the “smaller foot print” benefit. Its hard enough making up standard transformers. You also have very limited space for cable entry and exit.

BTW…..Beautiful installation!

Curt




[This message has been edited by caselec (edited 09-16-2006).]
Posted By: HotLine1 Re: Fan Cooled? Who asked for it? - 09/16/06 11:20 PM
Bob:
First, NICE install!!!

Second, I have to agree that the fans will become a maintenance issue for an otherwise 'maintenance free' item. (Excluding facilities that do PM)

I also take your side on the small footprint issue; good for a retrofit, not really 'good' for a new install. Seems like some of the mfg's have adopted an 'installer UNfriendly' attitude. The 'spaghetti' going to the fans is a distraction from your quality craftsmanship.
Stay safe.
John
Posted By: Ron Re: Fan Cooled? Who asked for it? - 09/17/06 01:20 AM
Fans required for full ratings on a relatively small xfmr .... BAD
Shunt trip MCS ..... BAD
I don't like it.
Now you have to consider AIC ratings when installing the transformer itself, not the just the devices upstream and downstream.
Now I have more non-adjustable protective devices to worry about when doing coordinations studies ..... BAD

The only fans that show up in my specs are very large pad mounted xfmrs that have dual ratings, in which most of the time the building will not reach the second rating anyhow.

[This message has been edited by Ron (edited 09-16-2006).]
Posted By: ShockMe77 Re: Fan Cooled? Who asked for it? - 09/17/06 01:48 AM
Nice neat work, Bob. I haven't done much work like this but I can appreciate the fine workmanship, right down to the same length of tape identifying the conductors.

I notice that the red, blue, and black legs on the secondary are grouped in 4, not 2. I was always under the impression that parallel installations were to be in groups in two. Could u tell me which NEC article permits this?

I'm not even going to get into the shunt trip, fan cooling discussion because that really exceeds my knowledge of transformers. But I appreciate the discussion. [Linked Image]
Posted By: mahlere Re: Fan Cooled? Who asked for it? - 09/17/06 02:56 AM
Shock, maybe one of the guys who knows the code better than I will correct me, but there has never been a code requirement for limiting paralleled conductors to 2. As long as you follow the ampacities in 310.16 and allow for derating as per 310.15(B)(2)(a) you can parallel as many conductors as you want. Heck you can even do them in groups of 3.

310.4 is the basic code for paralleling

392.8(D) gives the only place that limits the number of conductors. and this is only if you have A,B,C and a Neutral in the same conduit.

but then again, I tend to hide the code book more than look at it, so [Linked Image]
Posted By: RODALCO Re: Fan Cooled? Who asked for it? - 09/17/06 07:51 AM
Beautifull job, well done.
It is amazing how compact that 500 kVA transformer is.

The fans will give troubles in future and after a certain amount of hours will fail.
It wouldn't be a bad idea to fit an hour meter on the latter to get an idea how many hours the fans are actually working.

Perhaps preventitative maintenance (replacement) can be carried out on the fans after a specific amount of hours quoted by the manufacturer, to prevent a trip on overtemperature at an inconvient time.
Posted By: PCBelarge Re: Fan Cooled? Who asked for it? - 09/17/06 02:51 PM
Hello Bob
This is a nice looking installation. I have seen more and more of these transformers lately.

I do have a question about the support of the conductors terminated on the lugs. Do you have any concern about the distance they are installed without any support before they terminate to the lugs. With the vibration created in transformers, and the weight of all of the conductors per terminal, I myself do see the possible need for a bracket... maybe? It is sometimes hard to judge the distance in the photos provided.

Is the empty EMT for the GEC?

[This message has been edited by PCBelarge (edited 09-17-2006).]
Posted By: Lostazhell Re: Fan Cooled? Who asked for it? - 09/17/06 08:30 PM
First off, after seeing Bob's work on ECN before, this meticulousness in craftsmanship is par for the course. Well done [Linked Image]

2nd, I can't imagine a fan cooled xfmr being a good idea in most cases... to start, I'm picturing this thing with all kinds of office clutter, junk, folding tables, etc. stacked around it and imagining airflow being reduced quite a bit. While of course, this is against the rules, it's going to happen anyways.. And it's going to shut itself down. Another useless service call [Linked Image]
Posted By: sandsnow Re: Fan Cooled? Who asked for it? - 09/19/06 07:30 AM
Nice work Bob. I'm sure it took some thought to plan all that out.

I still can't get over the parallel primary being split to land on two switches. Please let us know if your inspector questions it.

Assuming it is a listed XFMR, I would want to know how UL answers the violation (in my opinion) of 310.4

Does that mean you can use two breakers to feed it? ;-)
Posted By: mxslick Re: Fan Cooled? Who asked for it? - 09/19/06 06:45 PM
Quote
Assuming it is a listed XFMR, I would want to know how UL answers the violation (in my opinion) of 310.4

IIRC, the NEC has no authority over the internal design of equipment, but can require the use of listed equipment. So the Code 310.4 wouldn't apply here, right?

I sort of envision it as like a motor control center, being fed with one feeder and splitting off internally through protective devices to individual motor controls.

On second thought, even an MCC would have lugs to land parallel feeders at the same point...hmmmmm

Looking closely at 310.4, it also says: (1999 NEC)

"The paralled conductors in each phase, neutral or grounded circuit conductor shall

(1) Be the same length,
(2) Have the same conductor material,
(3) Be the same size in circular mil area,
(4) Have the same insulation type,
(5) Be terminated in the same manner."
(Bold and italics above are mine.)

So I guess GE considers this setup as complying with the same manner, notice the Code doesn't specifically say the same location/lug.

Clear as mud!! [Linked Image]

edited to add:

And as the other have pointed out, very nice workmanship, Bob!! I wish I had your talent on my last cinema install!! (The EC was very sloppy.)

[This message has been edited by mxslick (edited 09-19-2006).]
Posted By: sandsnow Re: Fan Cooled? Who asked for it? - 09/19/06 10:10 PM
check out firdt paragraph of 310.4.
Note words in parentheses: (electrically joined at both ends to form a single conductor)

I don't know, maybe the conductors "end" past the switches and where the connections are made at the coils.

Also, you're right that the NEC is not to be used to inspect listed and labeled equipment. It does not say that we have to blindly accept it without being able to ask how this is justified.

I've seen planty of listed and labeled equipment that somehow slipped by and was shipped to the field with a deviation from the way the equipment was originally submitted to UL.
Posted By: XtheEdgeX Re: Fan Cooled? Who asked for it? - 09/20/06 02:41 PM
Just a comment on the parallel conductors. I've installed as many as 15 cables per phase before.
[Linked Image]
Posted By: Luketrician Re: Fan Cooled? Who asked for it? - 09/20/06 09:47 PM
What about the phase colors for 480v? For a time I know that we used brown, orange, & yellow, then orange was substituted for voilet. Wasn't this a code change back in 99'? Can't remeber for sure. Reguardless of the coloration, this looks like a fine definition of what quality electrical work should be.

[This message has been edited by Luketrician (edited 09-20-2006).]
Posted By: iwire Re: Fan Cooled? Who asked for it? - 09/21/06 09:36 AM
Thanks for all the kind words, I have not forgotten about this thread I will post some answers.

I have one concern and I would like to hear others thoughts on it.

I am not happy with how the lugs are offset from the bus bars.

Anyone have any info?

Should I be concerned?

The lugs are connected to the bus with 4 1/2" grade 5 bolts each.

Thanks, Bob
Posted By: bb Re: Fan Cooled? Who asked for it? - 09/22/06 12:56 AM
I just wanted to say that this is an extremely nice looking installation. It is very refreshing to see the pride that all of you guys take in your work!
Posted By: HotLine1 Re: Fan Cooled? Who asked for it? - 09/23/06 04:16 PM
Bob:
IMHO, I would ask the following questions regarding the lugs:
Did they come with the transformer? Probably not.

What documentation do you have, or could you obtain from the trans mfg regarding a "spec' on the lugs?

Does mfg want 'full lug to landing' contact, with ALL six (6) mounting holes utilized??

Also, looking at the full size pics, I may have a concern with the 'C' phase (secondary) buss and the bonding conductor. Please note that I am going by what I "see" in the pic; it looks like it's touching the buss???

John
Posted By: iwire Re: Fan Cooled? Who asked for it? - 09/27/06 08:37 AM
Hi John. Thanks for the email [Linked Image].

The bond has more clearance than it appears and more than I could provide at the grounded conductors.

When I go back I will try to get a better shot of them and the lugs.

I have darn little info from GE. Here is my thinking so far. I could have bought two separate two barrel stacker lugs for each phase. Had I done that I would have less contact area between lug and buss than I have now.

I may check the catalogs for better lugs but at this point it will most likely be left for the local inspector to decide if I actually change it.
Posted By: iwire Re: Fan Cooled? Who asked for it? - 09/27/06 08:43 AM
It's bothering me to much, I think I will order a set of stacker's (Fig 4)

[Linked Image from ebusiness.ilsco.com]

I just don't like how the present ones look, even if they function.

Bob
Posted By: HotLine1 Re: Fan Cooled? Who asked for it? - 09/30/06 11:23 PM
Bob:
Yes, GE response to inquiries leaves a bad taste with me also. USED to be good; last five years it's brutal.

The stackers on the center of the buss with two bolts, IMHO OK.

Personally, I would use all the bolt holes on the buss; perhaps a six barrel, six bolt?

Again, just my personal choice, and nothing against your install.

John
Posted By: Surfinsparky Re: Fan Cooled? Who asked for it? - 10/01/06 12:46 AM
Nice job for sure.
But am I lookin at it backwards.I thought it would be phased left to right not right to left.
Posted By: e57 Re: Fan Cooled? Who asked for it? - 10/01/06 09:07 AM
Bob - Oohh Ho Ya! Nice work!

The only thing I would worry about is the gutter on the right. Although sizable, it does have an abundant amount of conductor in it. Then they seem to 90 back, and flex out to the next enclosure. Once this thing has been humming for a few years one conductor might find a sharp screw or something.... I might have consisdered taking it over or under inside the trany to the back and out, but then again, that is a lot of wire to reach back there for.... [Linked Image]

Anyway.... Exceptional work! Other than that I would not worry so much about the lugs. If listed (the lugs) for that amount and size of conductor, with that hole pattern with a contact patch to the buss equaling or exceeding the cross-section of the intended conductor. I think you would be OK. Or you might be able to find better ones, but might not take that count of conductors the same way.

Hey, looking at the Ilssco page it appears you have T4A-4's?

And a little further I think I have your baby right here: USGL-350R64 ? 4 ports at 350MCM, 6 1/2" mounting holes... http://ebusiness.ilsco.com/webapp/w...d=-1&catalogId=1&categoryId=1040

Anyway, for the record I dont like the the Trany design, not your fault, but it seems to have redundant OCP (even if only for thermal) in a tight space and it's a vaccum cleaner to boot. [Linked Image]
Posted By: Ron Re: Fan Cooled? Who asked for it? - 10/02/06 12:04 AM
I just returned from a Square D Conference, where I joked with them about this dumb idea that GE has of using a 133% fan cooled rating to achieve the required values for a project.
They seemed nervous and told me that they didn't think it was so dumb. So look out in a few months, because even SquareD (Schneider) will have fan cooled xfmrs as a standard product. [Linked Image]
You can specifically order them without fans if speced that way.
Posted By: iwire Re: Fan Cooled? Who asked for it? - 10/02/06 12:20 AM
Mark, Thanks.

Quote
I might have considered taking it over or under inside the trany to the back and out, but then again, that is a lot of wire to reach back there for....

I wanted to do just that. [Linked Image] It would have been much 'cleaner'.

The problem is the coils literally touch the sides and the rear, there is no place I can enter on the rear sides. It is also very tight between the cement pad and the frame holding the coils.

I hear you on the trough, it's 12" x 12" with 16 - 600s and 4 - 4/0s. But I am not worried we measured like we where running pipe and used a hydraulic cable bender to shape the conductors to fit. There is almost no contact between the conductors and trough.

The conductors are resting on the 4" bushings of the flex and the RNC I used to line the holes into the transformer.

I have not been back to the job for a while, it still looks like it does in the pictures.

Bob
Posted By: caselec Re: Fan Cooled? Who asked for it? - 10/02/06 12:58 AM
Bob, I was just thinking about this transformer. Do the shunt trip breakers actually provide overcurrent protection or are they just molded case switches? The 150kva units I installed only had one breaker and I’m pretty sure it does not provide over protection. If the parallel breakers in your installation don’t provide overcurrent protection things could get ugly if one of the breakers opened automatically, manually or if the contacts of one of them developed a higher resistance.

I also question if this type of installation meets the intent of the NEC for parallel conductors. Connection half of the conductors to one device and the other half to another device doesn’t seem right. It has always been my understanding that parallel conductors should be connected together at each end and not terminate on different devices. I know when my local utility needs to splice parallel conductors all of the conductors of each leg get connected to a single connecting block.

Curt
Posted By: iwire Re: Fan Cooled? Who asked for it? - 10/02/06 01:02 AM
Curt they are simply shunt trip switches, I have the same concerns about one opening without the other.

All I can say if the inspector asks is 'I don't build them, I just install them'
Posted By: Dnkldorf Re: Fan Cooled? Who asked for it? - 10/07/06 03:19 PM
Bob, Kudos to you and your crew!!!!

Top shelf work.


So someone tell me, why are the fans at the bottom, and not on the top of the transformer?

How are going change them?

It makes sense to me to put them on the top, and suck the cool air off the floor, through the coils. And maybe add a filter to keep dust out. Fans would be easier to change.

Just my thoughts..
Posted By: CTwireman Re: Fan Cooled? Who asked for it? - 10/07/06 06:25 PM
Bob,

That is some hack work right there. You should be ashamed of yourself.

Peter
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