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Wireless smart meter measures your electricity use

Posting in Design

Smart appliances are supposed to help you save money by measuring the amount of electricity you use and then helping you reduce it. But a smart fridge, which can also keep track of your perishables, can cost well over $3,000 – that’s at least double the cost of a regular old one.

So Carnegie Mellon engineers designed a cheap wireless device that can monitor the power consumption of your appliances -- and it doesn't even need plugging in. New Scientist reports.

Plug-in electricity monitors exist, but can be tricky to install on large appliances; you don't even need to pull the dishwasher out from the wall to install this new one.

This smart meter runs for years on two AA batteries and uses electromagnetic waves to monitor the electric current flowing through the wires that plug your appliances into the wall.

  • Every time an appliance changes the amount of power it uses by turning on or off, the sensors pick up the corresponding fluctuations in the electromagnetic field (EMF) around the wire supplying the electricity.
  • The sensors use a wireless network to send this information back to a central power-monitoring system for the whole house.
  • This measures the increase in power use and links it to the appliance that tripped the EMF sensor.

The team installed the system in a family home and used it to monitor an LCD TV, washing machine, toaster oven, air-conditioning unit, laser printer, refrigerator, and iron. When compared with results form plug-in meters, this set-up measured the total power to 98 percent accuracy. (It did better with heavy power-use appliances like fridges than with small, intermittent devices like printers.)

The device was presented at the International Conference on Cyber-Physical Systems in Philly this week. The work was partly funded by Samsung Electronics.

[Via New Scientist]

Image: Samsung

— By on April 8, 2013, 3:00 PM PST

Janet Fang

Contributing Editor

Janet Fang has written for Nature, Discover and the Point Reyes Light. She is currently a lab technician at Lamont-Doherty Earth Observatory. She holds degrees from the University of California, Berkeley and Columbia University. She is based in New York. Follow her on Twitter. Disclosure