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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 10 days ago.

I designed these boards based on a schematic documented by Christopher McNally (copy can be found 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.

1. What the system will do?

The primary function of this system is to monitor power consumption in a home, business, or appliance/equipment. The device works on anything that uses AC power, and can monitor certain aspects of the function of a device or many devices simultaneously. This system, with the proper setup, is also capable of detecting ground faults and soil moisture levels.

When reading the power consumption of many devices, such as being hooked to the incoming mains of a home, the system should be able to interpret when an 'event' has occurred and be able to interpret the nature of the event.

2. Who are the users of the software?

This devices is intended to be used by business owners/operators, those in the agricultural industries, home owners, and marine applications. Essentially, this device is intended for use by anyone using AC power that either needs a better feedback loop than the 30 days that is provided by power companies through the billing cycle, or anyone that needs near real-time feedback of the power-state of a machine or multiple machines.

3. What are the business rules?


System Design Considerations:

Right now the only hard requirement is that there is a LAN network present. Each node in this system should be able to function independently, or as a part of a larger system. For example, if an Internet connection is present then the power monitor is capable of pushing data to allowing the user to view their data through that service, and if so desired a custom application could be built that pulls the data from the xively service, but if an Internet connection is not available then it is possible to push data straight to a user defined database, a pre-built system such as emoncms ( ), or a solution such as ( ).

That said, there should be a system defined configuration page that allows for a user defined formatting of the data string and a system setup selection with the previously mentioned options.

The only other option that I am aware of that parallels my project is the openEnergyMonitor ( ), however, there are a number of proprietary and open source home automation projects. The primary difference between my system and other systems is the 'base station', or lack of one. As stated previously this system is intended to work at a minimum with out any external appliances, only requiring an Internet connection. The proposed consumer system however would be a wireless b/n/g router with Ethernet hub and computer preferably built into the same box, this is intended to be used as the base station to communicate with all sensors (This is not a system requirement though, any home with a computer and a LAN setup should be able to install the software and build the system). This would allow anyone using the project to essentially be able to implement a 'plug and play' setup.

Another primary design consideration is to keep the system 'hackable' and open source. Design specifications for the computer/router are as follows:

- (currently using MySQL, phant needs to be tested)

- The unit is to be treated as a headless appliance with a web interface

- Programmed in python, interface uses flask and

- Router using dd-wrt or openWRT (havn't used yet)

- All data manipulations are done on the computer, sensors only report data

- The computer/router is an appliance that could be used as if a product in and of itself without external sensors

- Sensors are 'modules' allowing easy installation and incorporation for system expansion, as well as intuitive implemented use of custom user defined sensors

Sensor Design Considerations:

Power Monitor:

- Capture Temperature

- Capture Humidity

- Capture RMS Amperage

- Capture RMS Voltage

- Capture Instantaneous Amperage

- Capture Instantaneous Voltage

- Remotely Programmable

- Selection of Output String Formatting

- Selection of Output String Destination

Other board features:...

Read more »

  • 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
  • Hadoop

    10 days ago • 0 comments

    I spent a good part of the afternoon watching videos from this udacity course ( ). From the examples that they showed for using hadoop for sorting through logs I think that this might be a good tool to sort through my apache logs, and my xbmc/kodi logs and provide updates, as well as the inputs from various devices. There is going to be some learning curve, it looks like I will have to use hadoop, mapreduce, and I am not sure which, hive or impalla or both, and sqoop.

    If I get it to work I am hoping that I can use old computers as we generate them to break the throwaway cycle.

  • Current Rate

    12 days ago • 0 comments

    At the current rate I am posting data from one input at the rate of every 2-3s, and it looks like this will equate to ~3.5GB/yr.

  • A little more to show for the effort.

    16 days ago • 0 comments



    The data is static right now, but hopefully I will have it loading dynamically soon. I am going with a different node concept than what emoncms uses. Here, all nodes are virtual devices that provide an output based on processed information from a real device, and after creation are treated as a real device.

    Other than handling inputs this is all still 'smoke and mirrors' after this gets further along I will create it's own project page.

View all 31 project logs


J Groff wrote 8 months ago 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 8 months ago 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 9 months ago point
A MASSIVE amount of work on power monitoring has been done at OpenEnergyMonitor. Check it out.

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jlbrian7 wrote 9 months ago point
already seen that thanks

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Adam Fabio wrote 10 months ago 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 9 months ago 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 11 months ago 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 11 months ago point
the 150ohm resistor that ties the two lines together is the load

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jlbrian7 wrote 11 months ago 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 11 months ago point
You could also list 'em on Tindie. Seems like the appropriate place for that kind of thing.

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jlbrian7 wrote 11 months ago point
I will look into it.

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ucasano wrote 11 months ago point
How do I reach the github page?

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perez.ernesto.j wrote 11 months ago 1 point
just let me know ebay link, ill gladly support by buying at least one of the shields

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jlbrian7 wrote 11 months ago point
Will do. It should be up soon.

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