The best Transformer setup to use?

[Sizzler]

OK first let me start off by saying this is a great forum,and have been a reader for a while, and would like to thank all involved. Withthat being said let me explain as best I can what I am asking. I have a buildingwith a 1600 amp 480/277 service. Currently using about half of the availablepower. The building originally usedbarely any 120v equipment so only had a 75KVA either 208/120 or 240/120(Iforget its been awhile since been there) transformer which is now running about70-75% on all 3 legs, so taking anymore 120/240 off it is not an option. Have plenty480/277. Customer wants to add 2 tanning booths that ask for 60A 208/240 singlephase, in specs. they really only run at 45amps, so I am still going to use fornow 60A, so not to figure a load factor. Now what is best and cheapest way todo this. Customer states will not being adding anything else, so I need only enoughKVA trans to run the two units ( I was thinking about same labor to installanother 75kva step down with 225 amp panel to give room for future, he statesdon?t need anymore for future, I guess its going to come down to cost onthat) . So I am thinking installing one35-45KVA 3 phase to panel with one unit on AB phase and second on BC phaseleaving some room on AC phase, or maybe (2) single phase 480/277 to 120/240transformers would probably be around 12-14kva (if they make single phase480/277 units?) What are your thoughts on best/fastest/cheapest way. Thanks
Don
(if I left anything out which probably did, just let meknow)

 

[augie47]

Glad you decided to post. Welcome.
It's been a while since I've done any estimating, but as I recall, taking transformer, gear, etc. in account, your least expensive method will probably be a 25 kva single phase transformer.
Someone more updated on pricing may see where I am incorrect.

 

[beanland]

Is balance a problem?

Is balance a problem?

The cheapest approach is probably one 480V-240/120V single phase transformer. One 2-pole fused switch or breaker, feeding a small 200A MLO panel with two 60A 2-pole breakers. That is cheap but not elegant.

If I was the building owner, the 3-phase transformer and panel with room to grow would be my choice.

So, depends on who is paying.

 

[cadpoint]

Welcome to the forum!

Let me state the obvious (well at least to me)

I have to state that you have to know exactly what the size of the tanning bed is!

You really need the cut sheet on the beds and work out from the bed backwards and
not out from the power source forward.

I happen to be doing similar load calc's when I read your OP and just found it interesting that your numbers had to much float/fluff. Yes, tanning beds can be beasts but I just found it a
little unsettling.

Is 2KVA X 2 machinces a big deal, no not really but if it get up to a difference of your design verses a 3 or 4KVA x 2, then you talking a small oven.

Get the cut sheets, explain that this will be is will be the bases of your install.

 

[kwired]

Glad you decided to post. Welcome.
It's been a while since I've done any estimating, but as I recall, taking transformer, gear, etc. in account, your least expensive method will probably be a 25 kva single phase transformer.
Someone more updated on pricing may see where I am incorrect.

sounds like it would be a lot less than the 75 kva he was suggesting. Even a 37.5 would still be less and have some extra capacity.