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

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D.F. in the context of transformer load likely refers to the Demand Factor, which accounts for the fact that not all equipment operates simultaneously. The National Electric Code provides guidelines for reducing transformer size based on this factor, allowing for more efficient calculations. Users can input values such as kilowatts, power factor, quantity, and equipment D.F. into an Excel sheet designed for transformer sizing. There is some confusion regarding whether D.F. also refers to the dissipation factor or a derating factor, but clarification suggests it is primarily about demand. Understanding and calculating the D.F. load is essential for accurate transformer sizing and efficiency.
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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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