need help on a calcualtion

[fletcher]

I have to determine the gross and net demand loads of a power distribution for a large building complex with the following design data:

Lighting 2000 kW connected with 0.9 DF

Convenience power 1500 kW connected, with 0.1 DF

Mechanical systems 3000 kW connected with 0.5 DF

Elevators 1000 kW connected with 0.5 DF

Building systems 1000 kW connected with 0.8 DF

Estimated diversity coefficient 1.2

This is all the info I have right now. :?:

 

[charlie b]

That question was not formulated from requirements in the National Electical Code. I don't think we can help. I know I can't. This question presents information in a way that is very, very different than we use to calculate the load in a building. For example, we don't get "DF" values (I presume this is intended to mean "demand factor") like the ones in this question. We don't separate loads into the categories listed in this question. I have no idea what the difference is between "building systems" and "mechanical systems." And I have no idea what is meant by "diversity coefficient."

Whoever is teaching the course you are taking should have given you a process for performing this type of calculation. You will have to use their formulas to get the answer that they consider to be the "right answer." But understand that this answer is not the answer that an electrician or engineer would have to present to an electric utility or to an electrical inspector, in order to get power to a new building. This question has no meaning in the world of electrical design and construction. I don't know why your instructor believes that this question has any meaning in the world of real estate.

 

[fletcher]

tell me what way you would do it.

 

[tshea]

Need sq ft of building to start with. What is use? What are the electrical charactreristics of the connected equipment?

Basically the question you are asking is a 4 week course in electrical & design calculations.

 

[charlie b]

tell me what way you would do it.

The way I would do a real building design, or the way I would do this problem? I'll take a stab at this problem.

Not having taken the course you are now taking, I can only guess at the intent of the question. I would be inclined to multiply each given value of KW times the associated DF, and add them all up. That gives me a total of 4750 KW.

But I still don't know what is meant by "diversity coefficient." The field of "Electrical Power Systems Engineering" has a thing called "Diversity Factor." But it really does not apply to the types of information given in this problem. It has to do with a large system that is broken into many sub-systems. That said, my best guess of what the problem is asking you to do would be to take the 4750 and divide it (not multiply it) by the 1.2. That gives me a result of 3958 KW.