4000 Amp Busway

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deerhead

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I'm using a 4000A busway @120/208V to distribute power to 5 floors in apartment complex.

I'm feeding a 480V to 120/208V transformer than feeding busway. I need secondary protection (4000A) on the secondary side of transformer, before feeding the busway. What is the easiest / cheapest way I can achieve secondary protection at the transformer.
 
Ocp

Ocp

Before I would jump at the "easiest/cheapest", I would check the design, obtain the available short circut current at your transformer and the ratings of the buss devices to make sure you don't need to address any need for a current limiting device as a main.
 
Why not just have the Poco provide a second transformer at 120/208V....and keep the 277/480V service for house loads?
 
deerhead said:
What is the easiest / cheapest way I can achieve secondary protection at the transformer.
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I have concerns when my customers tell me they want work done the cheapest way.
 
What type of protection will the bus taps be at each floor? If they are fused bus plug switches, then use a fused switch at the secondary of the xfmr. If the bus plugs will be breakers, then use an enclosed 4000A breaker.
 
brian john said:
My question is why would you distribute at 120/208 in the buswaY?
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I was wondering the same thing.

It seems a 2000 amp busway with transformers on each floor, or even every other floor would be better way to go.
 
I agree with the others, given the size and cost of 480-208/120 transformer and 4000 OCPD, not to mention the 4000 amp busduct it would be much more economical to use a 480 volt busduct riser and install transformers on each floor.
 
4000A busway

4000A busway

The reason I said cheapest is because I'm already distributing 120/208V and I trying to save the owner money. The problem is the architect will not give up any floor space on the floors. As we all know every sq. ft they can rent out means revenue.

I guess what I was looking for is the best way to provide secondary protection at the transformer.

I need to meter each floor not individual rooms. I was planning on using a bus plug on each with a 1000A breaker to a distribution panelboard and meter on the line side on the distribution panelboard.

Any suggestions of another way to distribute 120/208V five stories?
 
Hate to beat a dead horse but the 480 distribution will still save space Smaller busway, bus FSS to ceiling mounted transformer MCB panel for distribution, footprint basically the same, less copper or aluminum, less labor to install (MAYBE), you are relying on multiple that are stock should you ever expierence a transformer failure . Better installation IMO all around.

5-250 kva transformers in lieu of 1-1500 KVA transformer rigging labor and cost of one large transformer.

Other that that a stand alone distributiuon bolted pressure switch with a busway adaptor is most likely the best way to go, though the manufacture of the busway may package a deal with a Circuit breaker or HPC fusible switch ect.....
 
4000A busway

4000A busway

I agree that distributing 480V is a better installation, but I'm informed that the rooms on each floor are going to be small and have to accommodate the systems also. I don't think it would be possible to ceiling/wall mount a 250 kva transformer in one of these rooms.

I have not had to layout a design that required feeding a 480V to 208V transformer then distributing onto a 4000A busway before. I was not sure if they made a busway adaptor that can accommodated a 4000A distribution switch. That switch has to be huge.

Thanks
 
deerhead said:
I have not had to layout a design that required feeding a 480V to 208V transformer then distributing onto a 4000A busway before. I was not sure if they made a busway adaptor that can accommodated a 4000A distribution switch. That switch has to be huge.

Thanks
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Not sure where you located, but around here switchboard manufacturers can build just about anything. A transition from a 4000 amp bolt pressure switch to a 4000 amp busduct shouldn't be a problem. However custom switchgear is costly.
 
More than likely all the gear you will buy at this amperage will be 480 VAC rated..

You have money they will build
 
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