Sizing transformer

[Malywr]

What size of transformer would be correct for 6 x 1670w 120V

Step down transformer 480v 3PH. To 208/120V 3PH

 

[augie47]

15

 

[wwhitney]

15

Is that because 10 kW isn't a standard transformer size for such transformers?

Because 10 kW would suffice for the load. [6 * 1,670 = 10,020, but 1,670 is surely only 3 significant figures, so the answer is 10,000.]

Cheers, Wayne

 

[wwhitney]

I got 9.28 what did I do wrong?

That would easier to answer if you provided your computation. But note that as the load is given in watts, we don't need any of the secondary or primary voltage info to size the transformer (or even know if the loads are 120V or 208V). And as there are 6 loads, they can be arranged in a balanced fashion. So the total load is a balanced 10,000 W (6 * 1,670W).

Of course, sizing the transformer at 10 kVA assumes loads of pf=1.0. If the power factor is less than unity, and 1,670 is really a W rating and not a VA rating, the current demand is higher, and so the transformer should be sized for a VA of 10,000W / pf.

Cheers, Wayne

 

[infinity]

But note that as the load is given in watts, we don't need any of the secondary or primary voltage info to size the transformer (or even know if the loads are 120V or 208V). And as there are 6 loads, they can be arranged in a balanced fashion. So the total load is a balanced 10,000 W (6 * 1,670W).

I deleted my first post because I was going to re-post with the calculation but you beat me to it. As you've mentioned balanced I see this as 3340 watts on the A phase, 3340 watts on the B and 3340 watts on the C phase.

 

[augie47]

Is that because 10 kW isn't a standard transformer size for such transformers?

Because 10 kW would suffice for the load. [6 * 1,670 = 10,020, but 1,670 is surely only 3 significant figures, so the answer is 10,000.]

Cheers, Wayne

yes

 

[Malywr]

yes

Thank you all for help


Sent from my iPhone using Tapatalk