Calculate amps from kVA

[robotguy]

I am a poor mechanical engineer trying to figure this out..
What is the formula for determining amps for a known kVA for 3 phase power?

 

[electricpete]

Complex power (in VA) = sqrt3 * Voltage (in volts) * Current (in amps)

1kva=1000va

 

[jstickley]

Just to add a bit of clarification to electricpete's post -- voltage in the formula is line-to-line voltage (which is the standard way of stating a three-phase voltage).

 

[robotguy]

Thanks!

robotguy

 

[RajT]

In three phase power ccts
Amps = kVA/^3xkV

Therefore for say the primary current Ip of a 3 ph 5000kVA trans rated at 13.8/0.6kV

Ip amps= 5000/^3x13.8
= 209.2 amps

Similarly the secondary current Is of the same trans would be
Is amps = 5000/^3x0.6
= 4811.2 amps

 

[robotguy]

Where does Power Factor figure into all of this?

 

[Ares]

Download a free elecrical calculator from

http://members.rogers.com/g.cygalski/electric.htm

It does the basic and more, no learning required.

 

[peebee]

Power factor does not figure into the kVA - Amps conversion.

It only comes into play when determining kW.

Of course, a low power factor means there may be an opportunity to correct it (using capacitors or other means), which would lower the kVA to a value closer to the kW value while simultaneously lowering amperage.

 

[jbartos]

Suggestion: The above equations are valid for the fundamental wave of electrical current and voltage. Nowadays with the nonlinear loads, the above equations may be somewhat off. It is a good idea to check for the voltage and current harmonic content or to simulate the power distribution system by adding nonlinear loads to obtain the harmonic content values.

 

[Foofoo]

For a simple way of finding Amperes for a 3 phase 415V system simply multiply the kVA by 1.39