# transformer sizing ????



## Vr_ecobox (Dec 6, 2007)

im in school right now and stuck on a project due later today and i need some help. here is the problem:

calculate the minimum transformer size for the loads as listed. Include the lighting based on the VA/sq ft of the type of occupancy, add 25% of the largest motor to the load and calculate all receptacle circuits at the amperage listed. Use any applicable lighting and receptacle demand factors in your calculations. If a second transformer is required to serve the single phase loads size the transformer KVA and add the primary amps of that transformer as a load on the 3 phase supply. Create a panel schedule that will list the number of circuits required to serve both the singe phase and 3 phase loads you have calculated, and how they will be connected to the 3 phase lines to balance the load. List the maximum line amps for each line of the 3 phase system will all loads connected at full calculated load. 


Factory
208 Y 120 transformer
144 ft. x 100 ft.

3 phase loads:
5-5 hp motors
6-15 hp motors
2-40 hp motors

1 phase loads:
80-120 volt general use receptacles
2-120 volt microwave circuits 20 amps
5-120 volt 8 amp grinders
2-208 volt 4.5 kw water heaters
lighting at 120 volts

any help would be greatly appreciated. im completely stuck!


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## brian john (Mar 11, 2007)

All this information is readily available in the NEC look at proper section, I assume your teacher has instructed you in the use of this book and the pertinent sections also look at samples in the back.


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