Electrical Load Calculation

[Binu-Kuwait]

Hi, 

Can someone explain what is the difference between Electrical Settings under Load classifications the Apparent load classification method, There are 2-options in where the load is getting a change if we use the settings change either or. can anyone suggest what is the impact on this (attached image). Iam using Revit 2020

- Some True Load and reactive load (1st option)

- Some Apparent load (2nd Option)

any help is highly appreciated and Thanks for your time

Binu

[Anonymous · Accepted solution]

The True and Reactive Load (Option 1) is trying to calculate the Power without the "phantom power" given off of Capacitors and Inductors. Haven't looked into the accuracy of the algorithm given but for my firm the apparent load is more than sufficient, just enter the power and exit with the same numbers on the Panel Schedule.

Here's a link to more information from AutoDesk

https://knowledge.autodesk.com/support/revit-products/learn-explore/caas/simplecontent/content/revit...

[Binu-Kuwait]

Hi Tyler,

Thank you so much. appreciate for your time, Noticed there is a slight load variations if we choose the option-1 as mentioned would like to explore the algorithm given in options.

anyone else experienced this issue kindly explore

Thanks again

[Guillaume.Chazal]

Hi,

I’m currently checking internally if we can get a document that would describe the difference between those two algorithms.

I’ll keep you informed in this thread.

Best regards

[Binu-Kuwait]

Hi Guillaume,

Thanks really appreciated 

[Guillaume.Chazal · Accepted solution]

Hi @Binu-Kuwait 

The settings dialog actually shows examples of the different outputs each method would provide depending on the provided inputs.

For both options, inputs are Apparent Load and Power Factor

Option N° 1:

The True Load and Reactive Loads are computed then summed.

Computation details for those two values can be found on this Wikipedia page.

NOTE: Revit uses the term “True Load” instead of “Real load” as in the Wikipedia article.

From those two values, the total Apparent Load and Power Factor are computed.

In detail based on the settings dialog above:

• Load 1
  • Apparent Load (S)= 1000VA,
  • Power Factor= 0.8
  • Trued load (P) is then equal to 0.8 x 1000 = 800.

Based on the Wikipedia article Reactive Load(Q) is equal to P x tan(arctan(Powerfactor)) = 800 x tan(arctan(0.8))= 600.

• Load 2:
  • Apparent Load (S)= 1000VA,
  • Power Factor= 1
  • Reactive Load is then equal to Zero.

From those two values, the total Apparent Load and Power Factor are computed.

• Total True value = 800 + 1000 = 1800
• Reactive Load = 600 + 0 = 600

Finally:

• Total Apparent Load = SQRT(1800² + 600 ²) = 1897.37 VA.
• Total Power factor = 1800 / 1897.37 = 0.9448

Option N°2:

In this case the total is computed by just summing the apparent load values (1000 + 1000 = 2000)

Then True Load values are computed and summed

From that, a power factor is computed.

• Load 1:
  • Apparent Load = 1000
  • Power factor = 0.8
  • True Load = 1000 x 0.8 = 800.

• Load 2
  • Apparent Load = 1000
  • Power factor = 1
  • True Load = 1000.

• Sum of Apparent loads = 2000
• Sum of true Loads = 1800
• Total power factor = 1800/2000 = 0.9

I hope you'll find this explanation helpful.

Best regards

[Binu-Kuwait · Accepted solution]

Hi Guillaume.Chazal

Thank you so much, really appreciated for your time

Kind regards..Binu