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Energy Meter

 
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aaronik19



Joined: 25 Apr 2011
Posts: 297

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Energy Meter
PostPosted: Fri Mar 02, 2012 3:18 pm     Reply with quote

Dear All,

I was google for some Energy Meter controllers like CS5463, MCP3900 and ADE7755.

Does someone have a link from where I can buy prototyping board because saw some on RS and seems incomplete (without CTs and Voltage transformers interfaces). More than this as a performance, which chip is most better and easy to implement? I want to read the following, VOLTAGE, CURRENT, APPARENT POWER, REAL POWER, POWER FACTOR, TRUE RMS.

Thanks for your great help.
asmboy



Joined: 20 Nov 2007
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Location: albany ny

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PostPosted: Fri Mar 02, 2012 3:47 pm     Reply with quote

Quote:

I want to read the following, VOLTAGE, CURRENT, APPARENT POWER, REAL POWER, POWER FACTOR,TRUE RMS


thats a pretty broad spec- and really this is a CODE forum -
not a basic circuit design discussion group.

i've done designs in that area - but pretty universally people get what they pay for when i do their design work.

do you want a concept and circuit thats YOURS or R U happy to have somebody else do the research for you ?

Another thing i i've noticed - copying the ideas of an original circuit designer can be dangerous to YOUR happiness - as that is the EZ way to produce something you don't really understand.
temtronic



Joined: 01 Jul 2010
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PostPosted: Fri Mar 02, 2012 6:36 pm     Reply with quote

You might just buy one of the 'kill-a-watt' energy devices,yank out their micro and start from the 'already working front end'...put a PIC inthere and get what you want.

I used that approach to get FCC type approval for telecom equipment,used a premade PC modem card,added my 16F877, sold the 'repackaged' product.
aaronik19



Joined: 25 Apr 2011
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PostPosted: Sat Mar 03, 2012 4:04 am     Reply with quote

thanks for your replies. Which kill-a-watt' energy devices you used? How you interfaced the PIC with this device? It has any output port?
temtronic



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PostPosted: Sat Mar 03, 2012 6:06 am     Reply with quote

model P4400..if my memory is still good.I only paid $30 for it.

I reverse-engineered their product to reconfigure for my PIC16F877.I 'split' the analog section away from their digital section.

Yes.Analog side has voltage as well as current outputs.
aaronik19



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PostPosted: Sat Mar 03, 2012 6:41 am     Reply with quote

ok I found it. So you opened the device and changed the design? Do you have any photos?
temtronic



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PostPosted: Sat Mar 03, 2012 7:43 am     Reply with quote

Yes, reverse-engineering means open it up, figure out what chip does what, then cut and hack to get what you need.

photos ? No, heck back then(10-15 years) I didn't even own a digital camera ! It was one of those 'bet-you-can't-do-this-in-less-than- a-week' bets and I won the 'coffee and donut' prize.The PIC16F877 talked to a laptop that I still have and it's 29 years old.

R-E is not magic, just a few hours of looking,recording,measuring, researching and basic R&D procedures.With today's free tools, what took me a week might only take a day or 2.
gpsmikey



Joined: 16 Nov 2010
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PostPosted: Sat Mar 03, 2012 10:14 am     Reply with quote

BUT --- do be careful poking around inside there - your standard house voltages are wandering around in there. Make sure you don't connect the 110v out to your PC or something - you can let the magic smoke out :-)

As Elmer Fudd used to say "be vewy vewy careful" :-)

mikey
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mikey
-- you can't have too many gadgets or too much disk space !
old engineering saying: 1+1 = 3 for sufficiently large values of 1 or small values of 3
Mike Walne



Joined: 19 Feb 2004
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What are you wanting to do?
PostPosted: Sun Mar 04, 2012 9:38 am     Reply with quote

Is this a pure learning exercise or the preliminary to a world's best product?

We need more detail to be able to help at all.

Your question is just too vague.

If you do not need isolation; all you require is a few resistors (maybe an OPA) a UART (or LCD) and loads of time to do software.

Mike
curt2go



Joined: 21 Nov 2003
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PostPosted: Sun Mar 04, 2012 8:30 pm     Reply with quote

I basically just did this.. All I did was used a hall effect chip ASC712 for the current sensing and just put a diode in for half wave rectifier and voltage divider into the A2D. Then you have to write a whole bunch of softare to track everything. The hardest was to get the power factor but it can be done by taking the zero crossing of the voltage waveform and then find out how long before the current gets there.. Its a VERY tough exersise. But if you are looking for metering precision that you will be charging for then this may not be the best. I did compare it to a Kill a Watt and it tracked the same.... You do have to run the pic at high speed to get the accuracy on reading the waveforms... I am running at 64 MHz on a 18F65K22....

Not sure if any of that helps.. But.. Smile TTY

here is the datasheet
http://search.digikey.com/ca/en/products/ACS712ELCTR-05B-T/620-1189-2-ND/1284593
Mike Walne



Joined: 19 Feb 2004
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No no no
PostPosted: Mon Mar 05, 2012 6:32 pm     Reply with quote

Quote:

I basically just did this.. All I did was used a hall effect chip ASC712 for the current sensing and just put a diode in for half wave rectifier and voltage divider into the A2D.

Not necessary. Simply provide a Vref/2 offset to two analogue inputs, pot down the voltage, and resistor sense the current, (with or without an OPA). A simple diode half wave rectifier throws away half your data, and introduces significant errors.
Quote:

The hardest was to get the power factor but it can be done by taking the zero crossing of the voltage waveform and then find out how long before the current gets there..

Power factor is NOT the same as cos( phase angle ). Yes I KNOW that's what you get from loads of text books, but it's just a SPECIAL case. Power factor is defined as the ratio of real power to apparent power. You can get both by processing the current and voltage data over an integer number of complete cycles. Here in the UK most electronic products HAVE to be power factor corrected, NOT to restore phase angle which is a capacitor job for inductive loads, but to compensate for the waveform distortion introduced by bridge-rectifier / capacitor ac to dc conversion.

Back in the 80's I did a reverse engineering job on a power analyser with respectable real time performance. They were using a good old 4MHz Z80 with 32k RAM & ROM. No need for a super performance processor either. Oh, AND it did an FFT on the current!

You can do a pure learning exercise for little cost in materials, and loads of programming effort. AFTER you've done that, you'll be in a postion to make much more intelligent decisions about hardware for your project.

Best wishes

Mike
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