Keeping your world up and running. ®

Fluke-1732, Fluke-1734, Fluke-1736, Fluke-1738 Difference between RMS kW and kW Demand

What is difference between RMS KW and KW demand.  We are trying to analyze max demand on a system.  the report gives us RMS KW and KW demand.  Trying to understand the difference.  Snapshot below of recordings.  One is the RMS Demand power, one is fundamental overview and one is overview with max demand all of the same recording but different values.


The Fluke-173X instruments have two features you manage when recording data, one is Average Interval and the other is Demand Interval.
When you go to start recording you have to manage both of those parameters related to the Intervals.
In your example I can see the Demand Table reveals the Interval to be 5 minutes. 
You didn't cut enough of the screen to show the Interval for the RMS Power and Fundamental Power parameters which will be the same and my suspect is they are different than the Demand Interval.
Based on that knowledge the results will be different because the Averaging will be over two different times. 
The other issue is the related to how the RMS Power and Fundamental Power reveal the maximum results.
To give you some background the sampling rate of the Fluke-173X is fixed at 120 samples per second and when you use the recording function the data is gathered at that sample rate. The Average Interval will tell the Fluke-173X to evaluate that length of time and keep the highest 120th of a second value and the Lowest 120th of a second value and Average all of the 120th of a second values to give a Average value and continue that process until you stop the recording. 
When you review the Overview Table is will show the Highest 120th of second value and the Lowest 120th of a second value over the entire recording period and the overall Average of all the Average results. 
The Overview Table of the Demand result gives you the Maximum Demand related to all the Average results instead of the 120th of a second Maximum results.


Have more questions? Submit a request


Please sign in to leave a comment.