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Power Monitor

Non-intrusive feedback loop for electrical systems.

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This project was created on 05/14/2014 and last updated a month ago.

I designed these boards based on a schematic in the pdf by Christopher McNally on my github page.

This board monitors the temperature and humidity of a room with the DHT22, and uses the current transformers to monitor amperage going through the main lines.

Each datapoint for the current readings in the Xively screen shot is the Peak RMS for each reading.

I have been using this board at home to monitor the electrical consumption in the house, but the board also can sense ground faults, and be used to detect soil moisture levels.

See PDF on github page.

There are many aspects of this circuit that I have not verified yet, however it has been serving it's purpose so far.

The use for this board thus far was to monitor the temperature in my Aunt's basement because she had become sick last year and unable to live at home.  I could see that the heater was working by current draw  and that the temperature was above freezing.  The board has remained in use all winter and worked flawlessly. Additionally I could see when someone was in the house because of the lights being turned on and off (this proved useful at one time because it provided the exact time of an incident).

I just got the go ahead to put this board in a heat treatment/annealing furnace and start collecting data in an industrial setting.  What I am hoping to accomplish here is to be able to see when the heating coils or igniter begin to fail so that they can be replaced before causing down time or loss of product.  

As the project progresses I plan on monitoring voltage to provide true power readings, as well as other sensors and control boards as necessary.

What I hope to provide for home use is a box that can be installed by an electrician and monitor power consumption and provide feedback for automation systems.    

  • 1 × DHT22 Temperature and Humidity Sensor
  • 1 × LM358N Amplifier and Linear ICs / Operational Amplifiers
  • 2 × 3000:1 Current Transformer or 2000:1 Current Transformer
  • 1 × Arduino

Project logs
  • Links

    a month ago • 0 comments

    This isn't really an update. I am just listing links I have come across while trying to figure out how I am going to deal with the data.

  • Water Meter Sensor

    3 months ago • 0 comments

    Spent some time playing with this in various configurations, but it is inconsistent at best due to the weak magnetic signal from the meter.  I want to order a few different Hall Effect sensors and log the data, but I will also try a photo reflective sensor.


  • Pics for Stack Question

    5 months ago • 0 comments


    Here you can see the copper around the GND pins.  I took this out so that the GND here looked like that of AREF and 13, but I ran wires on the top and bottom of the board.

    Here I was concerned about the white space, but since I did not have any trouble with this board version that did not have a copper pour I left it as it is.

View all 24 project logs


J Groff wrote 5 months ago null point

I wonder if you can pot these in urethane such that the sensors are not obscured, for ruggedization.

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jlbrian7 wrote 5 months ago null point

Conforma coat ...

and as far as that goes I thought if it ever came to it the board could be put in a watertight box and use amphenol or seacon connectors to mate with the electrical interfaces, but this would have to be a very specific situation.

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diysciborg wrote 5 months ago null point

A MASSIVE amount of work on power monitoring has been done at OpenEnergyMonitor. Check it out.

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jlbrian7 wrote 5 months ago null point

already seen that thanks

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Adam Fabio wrote 6 months ago null point

Looking good so far! Thanks for submitting your power monitor to The Hackaday Prize! Don't forget to upload some videos of the monitor doing it's thing - I really like the ground fault detection feature!

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jlbrian7 wrote 6 months ago null point

I should have a couple of video's up within the week. I have to build a box to induce a ground fault.

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arre_diels wrote 7 months ago null point

For an AC power monitor, you are missing a power-factor calculation, no? Just measuring the current will only do for resistive loads. (or am I missing the voltage measurement somewhere?)
Otherwise cool project though

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jlbrian7 wrote 7 months ago null point

the 150ohm resistor that ties the two lines together is the load

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jlbrian7 wrote 7 months ago null point

Sorry I misunderstood. You are correct I am not taking voltage measurements right now. So this only measures apparent power not true power.

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Jeff wrote 7 months ago null point

You could also list 'em on Tindie. Seems like the appropriate place for that kind of thing.

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jlbrian7 wrote 7 months ago null point

I will look into it.

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ucasano wrote 7 months ago null point

How do I reach the github page?

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perez.ernesto.j wrote 7 months ago null point

just let me know ebay link, ill gladly support by buying at least one of the shields

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jlbrian7 wrote 7 months ago null point

Will do. It should be up soon.

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