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

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Discussion Overview

The discussion revolves around understanding the term "D.F." in the context of transformer load calculations. Participants explore various interpretations of D.F., including its potential meanings and how to calculate it, particularly in relation to electrical equipment and demand factors.

Discussion Character

  • Exploratory, Technical explanation, Debate/contested

Main Points Raised

  • One participant seeks clarification on the meaning of D.F. and the equations for calculating it.
  • Another participant suggests that D.F. might refer to the dissipation factor, providing a link to an article for further reading.
  • Some participants propose that D.F. could mean equipment Demand Factor, explaining its relevance in reducing transformer size based on non-simultaneous usage of appliances.
  • There is mention of a derating factor, with one participant suggesting it is a common practice to apply a 20% reduction as a rule of thumb.
  • A participant expresses confusion about the absence of a "fudge factor" in the specifications provided.
  • Another participant acknowledges a misunderstanding of the spreadsheet and agrees with a previous interpretation regarding load factors.
  • A participant shares a link to an excel sheet related to the D.F. factor of equipment.
  • One participant requests assistance in calculating the D.F. load based on the provided information.

Areas of Agreement / Disagreement

Participants express differing interpretations of what D.F. stands for, with no consensus reached on its definition or the method for calculating it. Multiple competing views remain regarding its meaning and application.

Contextual Notes

Participants reference various factors and equations without providing definitive calculations or assumptions, leaving the discussion open-ended regarding the specifics of D.F. and its implications for transformer sizing.

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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