How to Calculate Demand from Apparent Power

I will give you the procedure how to do it, follow the procedure solve your question

Calculation of Electrical Energy

Are you sure that was the right link? I didn't see any thing about demand.

Finding Information on the Internet: Table of Contents

I understand what you are saying and I agree with you. The systems I'm measuring have very consistent loads so we don't have the issue of high inductive loads being turned on. Our utility calculates demand using a 15 minute window with an average for the peak every five minutes.

I have set these systems up in the past using a pulse off the demand meter of the utility. Not sure why your trying to make these calculations, but most people who wish to do this are wanting to control their demand charges.

I would suggest that you contact one of your local programmers in the area to work on this with you. The money that it may cost up front it minimal compared to saving potential.

I thought "demand" refers to KW load within a given time interval, in which case the

load Power Factor must be known. Thus for a 3-phase load, KW = Current X Voltage X PF X 1.732 / 1000. OR why not request your power supplier to conduct a load

sampling run using a 15-minute KW data logger or strip recorder say for 5 days.

Perfect. Thank you for the math. You are in fact right about the 15 minute window. The utlity company provides us with the max demand on our bill. We want to manage the max demand and knowing that 30 days later is no good. We want to know it now... before we hit the critical point.

Thanks

I'm not sure where you are located but in many cases if you ask for it the utility may provide an auxiliary contact off of the pulse output that they use. I'm still curious why you need this if the load is as constant as you say, and I wonder how you intend to manage the load under such circumstances.

If your calculations and the utility's don't agree then give them a call and ask them to meet with you to explain the discrepancies, in the US utilities are very sensitive to accusations of false billing and are usually bound by the state's utility regulating commission to assist you in every way possible.

Here's how the calculations are done:

www.electroind.com/pdf/Nexus.../E154701_Nexus1500_Manual.pdf

www.national-meter.com/dh96/DH96CPPmanual.pdf