electrical engineer help needed

[derby]

part one:

150kVA transformer; 120kW @208V

amps on each of the three lines/phases should be ~416A (150k / 360) for a "perfectly balanced" total of ~1250A, yes?

part two:

service from said transformer is feeding a panel through a 225A breaker.

this would be three lines/phases of 180A (80% of 225A) for a "perfectly balanced" total of 540A?

takeaway: i have up to 540A available as long as any of the three lines don't exceed 180A?

part three:

adding another 225A breaker/panel would give me an additional three lines/phases of 180A (80% of 225A) for a "perfectly balanced" total of 1080A, yes?

takeaway: i have up to 1080A available as long as any of the six lines don't exceed 180A?

i'm sure i'll have followup questions.  

[ducpainter]

pm suzyj...

...and wtf do you need 1K amps for?

[derby]

pm suzyj...

...and wtf do you need 1K amps for?

A "small" server room. 

[ducpainter]

You'll probably need 750 of them for AC.

[derby]

You'll probably need 750 of them for AC.

not a factor in these calculations. existing compressors are running off of a separate circuit.  

[ducpainter]

hmmmm...

small server room eh?

[derby]

hmmmm...

small server room eh?

compared to my four previous employers, yes.  

[Speeddog]

I see those advertisements for one little server that replaces a whole roomful of servers.
Perhaps that's what you really need.


<relevant info>

I think you only have ~577A to play with.

But, spark is not my forte, so YMMV.

[derby]

I see those advertisements for one little server that replaces a whole roomful of servers.
Perhaps that's what you really need.

that's the problem, i have a whole room of 'em. 

<relevant info>

I think you only have ~577A to play with.

i understand that to be correct for single-phase: I(A) = 1000 × P(kW) / (PF × V(V) )

three phase is: I(A) = 1000 × P(kW) / (√3 × PF × VL-L(V) )

http://www.rapidtables.com/calc/electric/kW_to_Amp_Calculator.htm

[suzyj]

You Yanks and your silly low voltages...

You're assuming 1.0 power factor, which isn't really kosher.

You'll need to factor in power for rack fans. Our Schroff racks at work pull 700W each, just for fans. There's 60 racks in our small server room btw, so that's 40KW just in rack fans. That's well before the chillers, not to mention all the crap that processes our noise.

Also your techs will hate you if you run at 80% of breaker current. Like passionately. Every time something switches on you'll pop a breaker. Sparkies usually spec the breakers for the cable size, so if you're running 80% you'll be wasting a lot of power just in heating cabling. Go the third panel. It'll cost a little now, but you'll recoup the dough in extra efficiency.

[derby]

You Yanks and your silly low voltages...

You're assuming 1.0 power factor, which isn't really kosher.

i thought i assumed a pf of .8 here: 150kVA x .8 = 120kW.

Also your techs will hate you if you run at 80% of breaker current. Like passionately. Every time something switches on you'll pop a breaker. Sparkies usually spec the breakers for the cable size, so if you're running 80% you'll be wasting a lot of power just in heating cabling. Go the third panel. It'll cost a little now, but you'll recoup the dough in extra efficiency.

not planning to run at 80% breaker, just trying to figure out where things actually go *pop*. 

i have a few options on the table, the additional panel(s) are just the tip of the iceberg. 

[Monsterlover]

[sno_duc]

Let your electrician worry about the amps.
You have 96 kw available for continuous duty (120kw times .
Add up the nameplate wattage of all the equipment this transformer has to supply.
As long as the total is under 96,000 you're golden.