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400A Feed to Rotating Building, NFPA 70E Compliant?

03/14/2013 8:28 PM

Hi all,

We have a building that will rotate 270 degrees with a 480volt/ 400Amp feed. Looking for options to make the electrical connection to the building. I thought I had seen something similiar to crane rail feeds. We looked at locamotive cables but, we need to crawl under the building four to five times a year.

We also need to tie in fiber optics and data.

Let me know what the great minds have to say.

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#1

Re: 400A feed to rotating building, NFPA 70E compliant?

03/14/2013 8:51 PM

If it is only rotating 270 degrees, bring them up near the core or point of rotation and bring them up in a loose spiral to avoid any stress on the cables. Make sure you are using Flexible cables (i.e. Not XLPE or MIMS).

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Sapper

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#2

Re: 400A feed to rotating building, NFPA 70E compliant?

03/15/2013 4:26 AM

Visit a sewage treatment works and find out how the rotating bridges operate on settlement tanks; usually the drive motor is on the bridge. Apply the learning to the building.

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#3

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/15/2013 11:43 AM

Slip rings designed at the center of rotation.

http://www.hubbell-gleason.com/engprod/SlipRings/Catalogs/SRHA400.pdf

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#4

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/15/2013 6:20 PM

1. slip rings

2. wireless

3. sounds like a job for an engineer

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#5

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/16/2013 6:29 AM

It all depends on the design of the rotating mechanism and how the center of the rotating platform is configured.

1- For the power cables, if the totalangle is 270 degrees only, you have several choices:

a) A Slip ring designed and dimensioned to carry the 400A load. This is easy if the center of rotation is free from any mechanism, and accessible.

b) A Flexible cable with enough slack to allow for the rotation of 270deg, without stress. The diameter of the coil and the point of anchoring should be big enough to prevent premature metal fatigue of the cable conductors.

2- The Fibre Optic link is a different issue. These cables do not like to be flexed frequently and require some expert advice if possible to be used on such rotating platform. BUT the way out of the problem will be to consider a wireless link.

3- Data Cable: either the same as the power cable connection, but not the slip ring! That is choice b), OR a wireless link again.

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#6

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/16/2013 8:55 AM

We normally use flexible cables for this and even larger rotations. You can use spot welding cable, but the ultimate in well insulated, fatigue resistant cable is military grade cable used for radar installations.

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#7

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/16/2013 11:45 AM

Rotating, at what speed .?

How many times , or cycle duty?

Building diameter?

Free space under floor?

Center hub diameter?

Any dwg to see?

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#8

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/17/2013 3:55 PM

Can you please provide details of the application including the traveling speed and estimated number of rotations per day, etc.

Is this some sort of telescope?

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#9
In reply to #8

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/18/2013 11:23 AM

Good morning and thanks for the suggestions.

Here is the link for the building.

It might track the sun. It is designed for testing windows, lighting, HVAC, and efficiencies.

This is for the department of energy and the architects, I use that term loosely, said it is design/build. Meaning no details on the electrical and data connections.

For the data side. They capture data in real time and gets fed to Cray computers. So wireless is a little slow.

Looks like a house, 31 inches under the perimeter for crawling around.

center base is about 10 feet in diameter,

utbf.lbl.gov/

we make it up as we go.

Thanks again and have a great week

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#10
In reply to #9

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/18/2013 2:57 PM

If it were me I would put all my effort into sourcing or designing a flexible trailing cable tray or reel system that would allow the cables to move and coil back automatically as the building rotates. The key part is the ability to put some strain on the cables so they coil back up when the building comes back around. Think of the cables fully coiled up at 0 degrees, uncoiled with some tension at 135 degrees, and then at maximum extension at 270 degrees (pic not included but hopefully this is clear enough).

This is the sort of thing they have on moving port cranes and can be done with data also, ideally with a single multi-core cable with a built in fibre to greatly simplify the design. For example....

Link

Much, much simpler, but you may have problems getting small quantities of this or other specialised cable (they may ask for a production run of a mile or so minimum, but you may be able to source shorter lengths).

Still it is a good place to start, also try an internet search for "reeling cable with fibre" or similar. Additionally a suitable reeling system may also be available or at least enough information for you to build one.

I have had some experience with high current and low power data slip ring systems operating at very slow speeds (low revolutions per hour or even day) or stopped for extended periods of time (as is likely the case here, for example if the building is following the path of the sun or just sitting in one place for extended periods of time) and that is not the way for you to go in my opinion due to brush to slip ring contact reliability issues (especially data) and maintenance difficulty. They are just too unreliable and difficult unless continuous 360 degree rotation is necessary, which is much more difficult (or impossible) to implement using cables.

Hope this helps, let us know how you go or if you need further clarification!

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#11
In reply to #9

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/18/2013 3:04 PM

Additionally, I may be over thinking things with my above post (which is much more "industrial" than you really need).

KISS, Keep it simple - perhaps a covered smooth cable tray to allow the cable to move and coil and uncoil with the natural rotational movement of the building like a watch spring with a separate cable tray (or spacers) on top for the fibre and data cables cable to do the same.

Dead simple and cheap with no specialised cables (other than flexible type power cables, possibly multiple single core flexible types to reduce the bend radius), reels or connections, so definitely worth a look as a first option.

Anyone here familiar with NFPA 70E requirements regarding this simple proposed solution?

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#12
In reply to #9

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

03/19/2013 3:43 PM

This is a DoE project and it's on the fly? Made up as you go? This gives some insight as to why we need a sequester!

Wireless data rates are only as slow as the check can be written. Additionally, if you have no bottlenecks at the bottom end, wireless data sampling can keep up just fine.

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#13
In reply to #9

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

04/18/2013 10:51 AM

What is the outside building diameter , it must be a fixed ring on the natural terrain or fixed floor , and a rotating ring conected with the internal ring , the 10 ft center's diameter.

Do you have any schematic?

Seem to be an easy thing to solve , the cable , if wraped in a drum at the center base will be about 24'-6" for a cable drum 5'2" radius.

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#14
In reply to #9

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

04/18/2013 11:16 AM

What is the outside building diameter , it must be a fixed ring on the natural terrain or fixed floor , and a rotating ring conected with the internal ring , the 10 ft center's diameter.

Do you have any schematic?

Seem to be an easy thing to solve , the cable , if wraped in a drum at the center base will be about 24'-6" for a cable drum 5'2" radius.

here in my city , we have a house that can rotate 360ยบ , made in the 1951, and it was translated all across the city.

See it ,

http://www.youtube.com/watch?v=xavO_A-XXPU

http://www.youtube.com/watch?v=TtFilKM8th4

http://www.youtube.com/watch?v=Mvb3_ROEkZ8&NR=1&feature=fvwp

please warning about if you open the IMAGES , it have some not to be seen.

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#15
In reply to #14

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

04/18/2013 12:41 PM

see it please, original -final place route of the rotating house

https://www.yousendit.com/download/UVJnN3RVdkc5bEROUjhUQw

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#16
In reply to #9

Re: 400A Feed to Rotating Building, NFPA 70E Compliant?

04/18/2013 10:32 PM

Please state if it is a 3 phase + neutral + ground , and voltage between phases for the 400 amp , or KW to supply

For the building ,I can see at the brochure, it seem to be a huge power to deliver.

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