3 phase amps to Watts

[watts-ae]

typical I would take, amps 3 phase x 1.73 x voltage x power factor = watts

I have read the actual loads of an ATS and got 20, 25, 30 amps per phase, how do I get total Watts?


Thanks

 

[GoldDigger]

Per line-to-line phase or per phase conductor? It makes a big difference.

 

[charlie b]

I have read the actual loads of an ATS and got 20, 25, 30 amps per phase, how do I get total Watts?

You start by dropping the phrase "amps per phase" from your vocabulary. I infer that you are telling us that phase A read 20 amps, phase B read 25 amps, and phase C read 30 amps. What you do next depends on the reason you are seeing a value for watts. If you just want an idea of what the load is drawing, and are not planning to use the number as part of a design process, I would take the average, and say the amps are 25. If you need to establish the existing load, in order to determine if there is spare capacity for adding more load, I would go conservative, and say the amps are 30. Take one of those numbers, and run it through your formula to get watts.

 

[watts-ae]

yes, thanks just getting an idea what it is drawing. I did take the average, it is a generator NEC looks at connected load, I know just checking actual loads
Thanks!!!!

 

[Carultch]

typical I would take, amps 3 phase x 1.73 x voltage x power factor = watts

I have read the actual loads of an ATS and got 20, 25, 30 amps per phase, how do I get total Watts?


Thanks

Line A Amps * Line-to-Neutral volts * Line A Power factor
+
Line B Amps * Line-to-Neutral volts * Line B Power factor
+
Line C Amps * Line-to-Neutral volts * Line C Power factor


If you have phase-to-phase amps, you need to first convert them to line amps, and include in the above total.
Line A Amps = sqrt(AB^2 + CA^2 + AB*CA)
Line B Amps = sqrt(AB^2 + BC^2 + AB*BC)
Line C Amps = sqrt(BC^2 + CA^2 + BC*CA)