www.delorie.com/electronics/powermeter/   search  
Power Meter

The purpose of this project is to monitor power usage in common residential circuit breaker boxes. Each board can monitor up to 16 circuits using common "current sense" transformers, and the power can come from common doorbell transformers (most homes already have one of these). Data is sent out via UDP (ethernet), providing an electrically isolated interface. The USB port is for programming the board.

Finally got a chance to hook up the prototype (two channels populated) to my panel box, on the refrigerator and septic pump circuits (see graph). For the fridge, note that the ice maker is running most of the time, except for the blip at 17:10 when I shut off the circuit breaker for a few seconds to make sure the meter was properly reading "zero". The tiny blips are when the door was opened and the light came on. The steps at 16:47 and 17:30 are when it runs the compressor. For the septic pump, you can see that the pump uses less electricity as the level of the effluent decreases. The Y axis is approximately "watts".

Current sense transformers I'm using:

R8C Programming Info
FTDI D2XX drivers


  webmaster   donations   bookstore     delorie software   privacy  
  Copyright 2011   by DJ Delorie     Updated Aug 2011