http://www.flashsense.com Energy, and simple things Sun, 20 Jun 2010 15:14:27 +0000 http://backend.userland.com/rss092 en Rather than re-invent the wheel, I thought there should be software out there that provides SCADA/HMI functionality for free. It is a commoditized activity by now.  After combing the web, I stumbled and settled on Mango, an open-source M2M solution. Mango is Java based that integrates with MySQL and runs ... http://www.flashsense.com/?p=684 I finally got around to spend some time on this and got everything on a perfboard . I also included a temperature sensor (LM35) along with a button to select the LCD display mode.  If I had to change one thing, I would chose different connectors so I can disconnect ... http://www.flashsense.com/?p=655 Modbus Well I got around to dabbling with how to best communicate with a host to implement a data historian. I started writing a extremely dumbed down protocol inspired by Modbus  After a day I realized that why settle for less and figured that pure Modbus would be better.  I could ... http://www.flashsense.com/?p=603 There is not much to this. A protoshield, the arduino, and a breadboard. Note the current transformer (donut). I have two of those to use in the panel. The first test was to plugging in a 60 W lamp to see what the measurement came too. I expected around 0.5 Amps ... http://www.flashsense.com/?p=553 Well I finally got around to get some code and test things out. Without known test loads and an oscilloscope, testing shall require some creativity.  Armed with a multimeter I began testing things out. Software The longer term plans include creating spot measurement devices  using the arduino and rather than slapping the ... http://www.flashsense.com/?p=498 Time to plan to interface to the  Arduino. The constraint is that the inputs can only be 0-5 volts.  So no negative voltages. Measuring the Line Voltage I am using a 9VAC 1.5A wall wart to step down the voltage. To shift voltage into a 0-5 range, I used the following circuit. ... http://www.flashsense.com/?p=385 Measuring Current There are two ways I am willing to entertain for measuring current. One is via a current transformer and the other vial hall effect. I combed the web to look for affordable devices in North America. It seems that Europe has access to cheaper current transformers.  I ended purchasing three  ... http://www.flashsense.com/?p=351 Earlier I spoke about modeling the math to simulate the calculations that I will be using in my home grown energy monitoring system. I think I have a good enough grasp on the math to come up with the algorithm to use in the software. Specifically, the computation of ... http://www.flashsense.com/?p=320 I used Excel to enter the power calculations on a simulated data set (voltage and current). I later wanted something more responsive to what-ifs and designed for mathematical computation. I stumbled on a MatLab like open source tool cal GNU-Octave. I decided to download and install the tool to ... http://www.flashsense.com/?p=261 I wanted to brush up on the theory before I jump to the implementation. So back to basic circuit analysis. Instantaneous Power In a steady state system, the voltage and current as a function of time consists of $latex v(t)=V_{max}cos(wt + \Theta_v) \qquad(1)&s=1$ $latex i(t)=I_{max}cos(wt + \Theta_i) \qquad(2)&s=1$ where $latex \Theta_x $ is is the phase ... http://www.flashsense.com/?p=43