What is D.F and How to Calculate It for Transformer Load?

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SUMMARY

The discussion centers on the Demand Factor (D.F) in transformer load calculations, specifically in relation to equipment such as stoves and washing machines in an apartment complex. Participants clarify that D.F refers to the Demand Factor, which allows for a reduction in transformer size based on the likelihood of simultaneous equipment operation, as outlined by the National Electric Code (NEC). The conversation also touches on the use of an Excel sheet for calculating transformer size, emphasizing the importance of understanding D.F for accurate load calculations.

PREREQUISITES
  • Understanding of Demand Factor (D.F) in electrical engineering
  • Familiarity with the National Electric Code (NEC) guidelines
  • Basic knowledge of transformer load calculations
  • Proficiency in using Excel for electrical calculations
NEXT STEPS
  • Research the National Electric Code (NEC) tables for Demand Factor calculations
  • Learn how to use Excel for transformer load calculations
  • Study the concept of Load Factor in electrical systems
  • Explore the implications of derating factors in equipment specifications
USEFUL FOR

Electrical engineers, electricians, and anyone involved in transformer sizing and load management in residential or commercial settings will benefit from this discussion.

JUJU_100
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I have seen an excel sheet in calculator to calculate the size of transformer.
There are option to put the vales of Kw,PF,Qty and Equipment D.F.
I could not understand what is D.F.
What is the equation to calculate the D.F and equation to calculate the total load D.F?
 
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D.F. likely means equipment Demand Factor. If the equipment is a stove or Washing and Drying machines in an apartment complex that furnishes these appliances, they would generally not all run at the same time. The NEC (National Electric Code) provides tables that allow you to reduce the size of the service transformer instead of calculating with all the equipment at 100%.
 
This is the link of the excel sheet- D.F factor of Equipment-

http://electrical-engineering-portal.com/download-center/electrical-software/calculation-of-size-of-transformer-fuse-and-circuit-breaker#comment-12292
 
I would have assumed derating factor. This would be a fudge factor thrown in where equipment spec is derated. Usually by around 20% as a rule of thumb.
 
I didn't see fudge factor in the spec.
Can anyone help me to calculate the D.F load?
 
Please See the below screen shot. Find the highlighted area
upload_2015-10-16_0-31-22.png
 

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