kva to amps

[Geoffrey Lyons]

My company recently purchased some import machine tool type equipment spec plate read only voltage 208, ph 3, power consumption 16 kva how do I convert kva to amps so as I can size my circuit properly

 

[nakulak]

no hp ratings ? what type of equipment ?

 

[Geoffrey Lyons]

nope has 4or 5 small servo axis drive motors it is a swiss style turning center typicaly all machines we recieve show voltage,phases, amperage, because of multiple axis and also spindles but every so often we get in varios equip rated in kva I have used ref book in past using transformer kva snd voltage and crossed to amps but would like to know proper way to calc

 

[EBFD6]

Electricalc plus works great, plug in numbers and hit enter.:wink: I love it! As far as the proper way I can't help, sorry.

 

[tkb]

Ohms Law

Amps = (kva x 1000 / voltage) / 1.73

44.46 amps = (16 kva x 1000 / 208 volts) / 1.73

 

[Harold-eng]

At 208V, 3-Phase, divide KVA by .360
At 208V, single phase, divide KVA by .208
At 480V, 3-phase, divide KVA by .831
At 480V, single phase, divide KVA by .48
At 240V, 3-phase, divide KVA by .415
At 240V, single phase, divide KVA by .24
At 120V, divide KVA by .12
At 277V, divide KVA by .277

 

[rattus]

Quite right:

Quite right:

Ohms Law

Amps = (kva x 1000 / voltage) / 1.73

44.46 amps = (16 kva x 1000 / 208 volts) / 1.73

Or, we can treat the load as a wye configuration even if it is not. Then the line current is:

Iline = 16,000 VA/(3 x 120V) = 44.4A

 

[Geoffrey Lyons]

thanx everyone!

 

[charlie b]

Ohms Law

Amps = (kva x 1000 / voltage) / 1.73
44.46 amps = (16 kva x 1000 / 208 volts) / 1.73

Correct answer. Wrong "Law." Ohm's Law does not involve power in any way.

 

[billsnuff]

charlieb

charlieb

you are saying using ohms law the answer must be in A, W, V or ohms, correct?

Ohm's Law defines the relationships between (P) power, (E) voltage, (I) current, and (R) resistance. One ohm is the resistance value through which one volt will maintain a current of one ampere.

( I ) Current is what flows on a wire or conductor like water flowing down a river. Current flows from negative to positive on the surface of a conductor. Current is measured in (A) amperes or amps.

( E ) Voltage is the difference in electrical potential between two points in a circuit. It's the push or pressure behind current flow through a circuit, and is measured in (V) volts.

( R ) Resistance determines how much current will flow through a component. Resistors are used to control voltage and current levels. A very high resistance allows a small amount of current to flow. A very low resistance allows a large amount of current to flow. Resistance is measured in ohms.

( P ) Power is the amount of current times the voltage level at a given point measured in wattage or watts.

 

[charlie b]

you are saying using ohms law the answer must be in A, W, V or ohms, correct?

Not correct. It would be correct if you dropped the "W." Your explanations and relationships are all reasonably correct. But they do not all come from "Ohm's Law." In other words, it is true that power equals voltage times current, but it was not Ohm's Law that said so. All that is covered by Ohm's Law is the relationship between voltage, current, and resistance: E = IR.

 

[jghrist]

Watt's Up??

Watt's Up??

charlie b: See http://www.the12volt.com/ohm/ohmslaw.asp
billsnuff: See http://en.wikipedia.org/wiki/Ohm's_law

 

[billsnuff]

i getcha, E=IR.

But if I google it or look in Ugly's, P is always added to the circle. Thanks

 

[charlie b]

http://www.the12volt.com/ohm/ohmslaw.asp
[URL="http://en.wikipedia.org/wiki/Ohm's_law"]http://en.wikipedia.org/wiki/Ohm's_law[/URL]

Thank you for inviting my attention to those two web pages.

The first one is wrong. Flat out wrong. That's all there is to it. I am right, and it is wrong. It says that "power" is somehow related to Ohm's Law. It it not.

Why should you believe me, and not that web site? You should not. You should look for other reliable information sources, and judge for yourself. But for what it may be worth, I do have BS and MS degrees in Electrical Engineering, and I made it as far as passing the PhD Qualifying Exam before I had to abandon my attempt to get a PhD.

I do not like the notion of wikipedia, and would never use it as a reference source. In this particular case, it happens to have the description right. Not because it is a good source of information, but because it has the information right this time.

So please take a look at the wikipedia description, and take note that there is no mention of power.

Let me say again: There is a relationship between power, voltage, and current. But if you want to learn what that relationship is, then you have to look somewhere other than in Ohm's Law.

 

[billsnuff]

thanks again charlieb. watts = James (steam engine) Watts

 

[tkb]

Correct answer. Wrong "Law." Ohm's Law does not involve power in any way.

OK...Ohms Law is only E, I & R.
Is there a name for the Law with the P?

 

[wirebender]

Ohm's law:
V=I/R

Watt's law:
P=V*I



Edit: I still had a page to read when I posted this, sorry.

 

[rattus]

Joule's Law:

Joule's Law:

Ohm's law:
V=I/R

Watt's law:
P=V*I



Edit: I still had a page to read when I posted this, sorry.

I believe Joule's Law is the correct reply.

 

[LarryFine]

Ohm's Law states that one volt will push one amp through one ohm.

 

[rattus]

Ohm's Law states that one volt will push one amp through one ohm.

Fine, Larry--hey that's your name backwards!

But how do you maintain that one volt, and where does the current flow?