Counter Log - Help with kWh calculation

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Ricardo Pinto
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Hi people,

May I ask a little help about counter log?

I have a power sensor on an electric board. On ETS, I get an Instantaneous Power object (2 bytes), which comes in kW format. Like, if the house is consuming 1200W, I get 1,2 value on ETS, if it's consuming 250W, I get 0,25 value, and so on. I have the correct instant values showing on visualization.


I've tried to create counter logs, to get an approximate daily consumption, etc. The problem is that the values on the counter log don't make any sense.


For example, if the house is consuming constant 250W during 24hour, I should get 6 kWh by the end of the day, but the values don't make sense. On one day, it showed something like 138kWh on one day, which is impossible. I deleted all data now.


Either I'm configuring all wrong the counter log, or there's something I'm missing.

Thanks for any help

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Ricardo Pinto

Hi Fabien,

I decided to investigate some ways to do the calculation every second, and unfortunately the General timer doesn't have any seconds, just hour and minutes, so I'll have to work with something like Operating time or Timer to count the seconds.

Meanwhile, I've discovered a bug on those functions, 5 seconds missing in each minute.

Until then, there goes the precision calculation. I will try it anyway, to do an approximate calculation, but it will never be 100% accurate until the 5s missing per minute is fixed.

Best regards

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Fabien Fuster

Just created a fake entry of constant 250 and run it through a calculation before logging... I'll keep you informed of the result.

In parallel I've made a second test logger with my real consumption entry though a similar calculation node....lets see.

Regards,

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Ricardo Pinto

Interesting approach... So basically the calculation is done every second, and I need to care of the sum of the values.


Great, thanks for the tips. Will think about it over the weekend, I'll keep you posted.

Btw, I think the counter log should be doing this...


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Fabien Fuster

Well.... not sure at all my approach will be correct here, but lets start somewhere.

If you are able to get the power consumption in W per second, the the following calculation could match (if not mistaking):

We can suppose 1 Watt / 1 second = 0.001 KW / 1 second.

So  for 1 Hrs we should have 0.001/3600 = 2,777777777777778e-7 KWh

Now if you multiply this value per the instant consumption value and sum it up you will get the correct value.

ie. 250W * 2,777777777777778e-7 * 3600 seconds * 24 Hrs = 6 kWh.

Now, my only doubt is how to force the counter log to do the calculation every seconds, but maybe you have the answer...

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Ricardo Pinto

Yep, DPT 13.013 here...

I really don't know what's wrong...it's pretty weird. Never understood this values, that's why I wanted to just use the current power and leave the calculation to bOS.

Maybe it's a stupid question, but if I know the instant consumption, and use it on a counter log, isn't it suppose the counter log to "see" how much power I used on a certain period of time?

Do I need any extra calculation?

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Fabien Fuster

Knowing you, I'm sure you have the right one, but just to xcheck : are you using DPT 13.013 ?

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Ricardo Pinto

Hi,

I suppose... but the problem is that the values returned by the last hour consumption etc, don't make any sense, even on ETS.

It's supposed to be 4-Byte signed values, as far as I noted. On ETS, I receive stupid values like 00 00 00 03, and I'm like what?! So in bOS the values show as 0, so I don't know where to go...

Plus, the values returned from KES are pretty weird. For example, I get values for the last hour cost, and day cost etc, but they also don't make sense. Today I'm getting a last hour cost of 0,05€, and a day cost of 0,04€...yeah right.

That's why I decided to use the instantaneous power, which is real time consumption, and use it on a counter log, because the only true correct value I'm getting from the KES is the current power.

Best regards

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Fabien Fuster

Hi Ricardo,

Sorry for the mistake, was too quick... However, looking the right documentation (I hope ;-) - ZN1IO-KES), it seems you can send the hourly Energy consumed and even the daily one (refer the active energy section 3.3.1). Would this not be suitable ?

Fabien

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Ricardo Pinto

Hi Fabien and Andy,

I'm not using the KES PLUS, but the KES ENERGY SAVER, which got recently discontinued. Still, it looks a good device. The KES PLUS actually has more options than this, so I don't have most of the options shown.

This older unit, actually let's you get the instantaneous consumption, and I think it calculates the daily weekly and monthly consumption, but I was looking forward to use the counter log from bOS to create my own graphic instead of just getting the values from the KES.

That's why I'm not quite understanding how the counter log works.

I'll try to find any kWh values reading as Andy refered.

Best regards

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Fabien Fuster

Hi Ricardo,

Looking into the Zennio documentation, it seems you can configure the output to be in kWh and get what you are looking for:

There quite a lot of configuration possibilities, pending what your installation looks like and what you want to achieve. Seems to be a pretty cool device... I hope this will allow you to manage what you are looking for, it is difficult for me to be more precise not having the details of your installation and expectation. 

Regards,

Fabien


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