Trend Log Aggregate

[Kai-Roger]

Hi

Can someone please give me a technical explanation of what Trend log "Aggregate function" means?

BR
Kai-Roger

[admin]

Each trend stores data for 3 periods:
1. Every minute (for the last hour)
2. Once every X minutes (X = user selectable)
3. Once per day

Data is added to the trend log once a minute. After that, data for the selected period and daily period is processed by the selected function. Previously, this was only an average value, now you can choose from: average, minimum, maximum and last value.

[Kai-Roger]

Thanks

[JMM]

Hi,

Can confirm me that a trend in 5 minutes, absolute value, maximum: Has to give the maximum value of 5 last minute

BR.

[admin]

Object value is sampled once every minute. If you want to know the absolute minimum in a specific time interval then you need an additional event script.

[Evens]

Hi, 

I have several SE powerTag`s that communicates on Modbus TCP to my LM. I have an object for each PowerTag that counts KWh. On these objects I have trend logs so I can see the KWh on a day to day basis.
My question is, what is the difference between Aggregate function Average and Maximum? Because I see that when I use Maximum the trend log is way to high.
Example: one day I used 17 KWh, on the average trend log I measured 17 KWh, but on Maximum trend log measured 142 KWh. Why is there so much difference?
 
BR Even Sundgot.

[edgars]

Hi Even,
each minute a sample of data is taking to use later in the defined resolution.
With aggregate function you are defining which sample to take. So if Maximum = during the minute you take maximum value of all datapoints.

[Evens]

Hi Even,
each minute a sample of data is taking to use later in the defined resolution.
With aggregate function you are defining which sample to take. So if Maximum = during the minute you take maximum value of all datapoints.

Hi Edgars,
 
Thanks for the info, in my head it sounds like I should use maximum. But I can’t get it to work correctly. What am I doing wrong?
 
My setup:
In my switchboard I have approximately 20 fuses. I have placed a KWh counter on these fuses:
1x Main fuse.
1x Heating fuse.
1x Light fuse.
 
I have the readings from my power company, when I compare the main fuse to the list from the power company, it is totally wrong when I use Maximum. But when I use Average it seams correct.
 
But then again, I have some other problems. When calculating remaining KWh I take the KWh Main fuse – (KWh Heating fuse + KWh Light fuse) the result i am getting is an negative value. So, it seems to me that my readings are wrong.
 
What is the correct way to trend KWh? and how accurate is the measurement?
 
BR Even Sundgot.

[Daniel]

Hi
Use counter with negative delta and average.
BR