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aaronik19
Joined: 25 Apr 2011 Posts: 297
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Energy Meter |
Posted: Fri Mar 02, 2012 3:18 pm |
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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. |
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asmboy
Joined: 20 Nov 2007 Posts: 2128 Location: albany ny
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Posted: Fri Mar 02, 2012 3:47 pm |
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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. |
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temtronic
Joined: 01 Jul 2010 Posts: 9171 Location: Greensville,Ontario
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Posted: Fri Mar 02, 2012 6:36 pm |
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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. |
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aaronik19
Joined: 25 Apr 2011 Posts: 297
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Posted: Sat Mar 03, 2012 4:04 am |
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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? |
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temtronic
Joined: 01 Jul 2010 Posts: 9171 Location: Greensville,Ontario
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Posted: Sat Mar 03, 2012 6:06 am |
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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. |
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aaronik19
Joined: 25 Apr 2011 Posts: 297
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Posted: Sat Mar 03, 2012 6:41 am |
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ok I found it. So you opened the device and changed the design? Do you have any photos? |
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temtronic
Joined: 01 Jul 2010 Posts: 9171 Location: Greensville,Ontario
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Posted: Sat Mar 03, 2012 7:43 am |
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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. |
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gpsmikey
Joined: 16 Nov 2010 Posts: 588 Location: Kirkland, WA
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Posted: Sat Mar 03, 2012 10:14 am |
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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 _________________ 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 |
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Mike Walne
Joined: 19 Feb 2004 Posts: 1785 Location: Boston Spa UK
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What are you wanting to do? |
Posted: Sun Mar 04, 2012 9:38 am |
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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 |
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curt2go
Joined: 21 Nov 2003 Posts: 200
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Posted: Sun Mar 04, 2012 8:30 pm |
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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.. TTY
here is the datasheet
http://search.digikey.com/ca/en/products/ACS712ELCTR-05B-T/620-1189-2-ND/1284593 |
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Mike Walne
Joined: 19 Feb 2004 Posts: 1785 Location: Boston Spa UK
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No no no |
Posted: Mon Mar 05, 2012 6:32 pm |
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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.
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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.
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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..
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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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