Designing DC energy meter using 89C51 micro

[mak_goel]

Hi everbody
I want to measure dc wattage by using 89c51 micro. Kindly help in this regard.

Regards
Mak

 

[master_picengineer]

DC energy meter

It had been posted in this forum a such question (designing a watt meter using Pic). Sorry I couldn't find the link. try to find it.

 

[mak_goel]

Re: DC energy meter

Thanks for giving your valueable time. I also tried to serach but couldn't find.
KINDLY HELP ANY BODY.


Mak

 

[master_picengineer]

DC energy meter

Hi,
Please find here the link:


Other useful links:








Don''t forget to push the helped me button.
thanks.

 

[master_picengineer]

DC energy meter

Hi saahilgoyal,
Please give details so we can help you.
What do you mean by prepaid ?

 

[mak_goel]

Re: DC energy meter

Dear,
All the links are related to AC Pwer measuring & dc voltage & current display. But my concern is dc power measurement. Pl guide in this regard by using 51micro core.

Thanks
Mak

 

[penoy_balut]

DC energy meter

if you can read dc current and voltage then simply multiply to get power (W=E xI )

 

[master_picengineer]

DC energy meter

Yes, In fact !

 

[mak_goel]

Re: DC energy meter

Thanks for your response. I want to draw your attention to below point also:
If Instantant Voltage & current is multipilied then output will be instant power. But i have to measure enegy consumed for 1 month. Below formula can give the desired output:
Consumed Energy (30days)=[(P1+P2..........P3600)/3600]*24*30KWH
Where P1=Measured Power after each second
My concern is accurecy with this process as i dont know what will be the practical impact of the same path.

Kindly give your practical views if possible.

Thanks
Mak

 

[sumit_techkgp]

DC energy meter

sample input current and voltage and convert synchronously into digital. multiply them and then make a low pass filtering on them to get the dc power(the cut-off of this filter should be your harmonics frequency u want to measure), then convert this number into BOT. Thingsa are not so simple. See analog devices energy metering systems to get a full overview. Lot of other thiongs are required to consider. metering standard itself is critical and u need to meet them (the converter itself should be a sigma delta....means u are gone ). I have practical experience on this thing and i know it is not so easy

 

[mak_goel]

Re: DC energy meter

Thanks Sumit.....
I have seen aanalog device ICs and no doubt, there are so many parameters to be considerd. But again my point is that all the parametrs are required for DC Power measuring also or not. We can use the Analog Device ICs for this application or it can be done only by Micro. Can u pl share your practical experience with me.

Thanks again for your guidence...........

Regards
Manish Goel

 

[ravimarcus]

Re: DC energy meter

If Instantant Voltage & current is multipilied then output will be instant power. But i have to measure enegy consumed for 1 month. Below formula can give the desired output:
Consumed Energy (30days)=[(P1+P2..........P3600)/3600]*24*30KWH
Where P1=Measured Power after each second
My concern is accurecy with this process as i dont know what will be the practical impact of the same path.

Instant power / 3600, next second do the same thing. You will be integrating the power. When the reminder provides you a 1 as reminder increment UNITS counter. You will get energy in UNITS consumed.

Hope this helps.

Cheers

Ravi

 

[mak_goel]

Re: DC energy meter

Thanks Mr. Ravimarcus,
I already taking this one in same way but my worry is for taking accurecy. Have you done this type of project. Pl share some practical views.

Thanks
Mak

 

[ravimarcus]

Re: DC energy meter

I already taking this one in same way but my worry is for taking accurecy. Have you done this type of project. Pl share some practical views.

Yes, I have done this before.

In one project, I was receiving 4-20mA and I was integrating this.

In the second project, I was multiplying voltage and current resulting in instant power. I was integrating and producing UNITS.

For example
In the 1st sample, you will get a Pi of 2400. Divide this by 3600, you will not have any carry. Retain 2400.

In the next sample, you will get a Pi of 2400. Add the retained 2400 to the current sample. You will get 4800. Divide this by 3600. You will get 1 and a reminder of 1200. Retain this for the next sample.

The 1 is the UNITS.

The accuracy will depending on your 1 second sampling.

Cheers

Ravi

 

[mak_goel]

Re: DC energy meter

Thanks Ravi your for your fast respone.

The accuracy will depending on your 1 second sampling.

Pl clarify below also:
1) I couldn't understand the above line exactly.
2) What are your views abt sumit_techkgp reply as posted earlier.
3) Is it possible with 8 Bit Controller to complete this type project while enrgy storage for 1 month wil be app. 7000.000KWH.


Thanks & Regards
Mak[/code]

 

[ravimarcus]

Re: DC energy meter

Pl clarify below also:
1) I couldn't understand the above line exactly.

Your sampling have to be accurate for accurate measurement.

If you sample at say 900 mS, then you will not be able to achieve KWh. Your value will be off by 10%. Hope you have understood now.

2) What are your views abt sumit_techkgp reply as posted earlier.

He has a point there, but too many conversions will result in losses. In any design, at the earliest, convert the analog data to digital and then play with the values, This way there will be no drift and more inaccuracies.

3) Is it possible with 8 Bit Controller to complete this type project while enrgy storage for 1 month wil be app. 7000.000KWH.

8 or 16 bits are not the issues here for accuracy. 7000.000KWH is only a counter. You can have more than this using 8 bits uC.

Cheers

Ravi