A building load (Diversified Load) is 433kw, and all the attached load is 1-Phase load, not any single load is 3-phase in building! Should we divide load by 3 to make it 3-phase arrangement for transformer sizing or we should simply divide it P.F to size transformer? (3-ph VAC=415, 1-Ph VAC=230).
Transformer sizing
- Thread starter Arsii
- Start date
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
How was the 433 arrived at? Is this a measured or NEC calculated value?
electrofelon
Senior Member
- Location
- Cherry Valley NY, Seattle, WA
Are you under the NEC? The NEC doesn't cover sizing transformers, but would cover the transformer protection OCPD. The OCPD can typically be only 125% larger plus next size up than the transformer (for <600V) so there is a limit to how small you can size your transformer. Calculated loads are often two to two and a half times actual load so under the NEC transformers are typically way oversized so I would typically try to make it as small as possible if using a calculated load. Measuring actual load or demand is a much more accurate way to go, but obviously it won't work for a new build.
- Location
- Wisconsin
- Occupation
- PE (Retired) - Power Systems
Is your kW value based on all L-N loads or some of them L-L?
Can your loads be distributed evenly across all three phases? If so you can simply divide by 3.