Fluke 43b help and logging max demand

dlt27 · May 26, 2021

Hi all, I have brought a fluke 43b to log a local farm to see how many amps they are using at maximum demand.
The meter gives 3 readings for each time interval. Min, max and average. I would understand if the readings were between 2 time periods, but don’t understand how you can have three readings at any time period. Ie if I move the cursor the meter gives me 3 readings at that time period. I have enclosed images of meter screen and downloaded screen on pc. Can anyone explain if they understand where I’m coming from. I want to see the maximum load the farm is pulling and for how long. Kind Regards

pc1966 · May 27, 2021

I suspect the logger only records values at, say, 1 or 5 min intervals, and the values you see (min/ave/max) when you move the cursor around are the statistics for the corresponding interval.

You would need to study the manual to see what the intervals are as "max demand" is kind of flexible. Your absolute peak max on very short intervals is the sort of thing that could possibly hit the instant magnetic trip of MCB/MCCB so clearly you want to avoid that, but for supply sizing and incoming fuse ratings, etc, you really are looking at keeping the "average" over a minute or so to below the rating.

The Devil very much is in the detail, or rather, your current/time characteristics of the OCPD.

snowhead · May 27, 2021

Is it showing Max from the start of monitoring up to that point in time and the same with Min and with Average?

Just had a quick look at the manual.
The Fluke reads faster than the time intervals displayed so the MIn, Max, Ave is inbetween the displayed times points.

However it looks like Volt / Amp /Hertz is an overview, you need to be on Sags and Swells for more details records.

dlt27 · May 27, 2021

Hi, thanks for replies. I thought it was max, average and minimum from start to the point the cursor is on, however when I move cursor max was 70A for example at a point on the graph, but before that point it peaked at 120A so if it was from start it should say 120A as max, but it doesn’t. The max, min and average change with each point on the graph. I can tell each point on the graph is about 1 hour 10 mins.
When I am logging the mains to check for loading should I set to sags and swells then?
The farm is on a single phase supply and wanted to see if overloaded. From the graphs would you say it is? Thanks ( sorry for being thick, was hoping it was just like a normal fluke clamp meter and would just give one reading for the current).