Power-hungry home appliances identified by MIT device

The device by a team from the Massachusetts Institute of Technology (MIT) is no bigger than a postage stamp. When attached to an incoming power line, the sensor can differentiate between various appliances based on their patterns of consumption and detect how much power is being consumed by each. It also spots any unusual patterns.

Information about every appliance in the house can be displayed via special software developed by the team.

"For a long time, the premise has been that if we could get access to better information about energy use, we would be able to create some significant savings," said Steven Leeb, Professor of Electrical Engineering at MIT and lead author of a paper published this week in the IEEE Sensors Journal.

Other teams have tried to solve this problem with different approaches in the past. However, the MIT solution offers several advantages. For example, in the past, each appliance would have to be connected to its own monitor. The system also doesn’t require any rewiring or disconnecting of cables and is completely self-calibrating.

Some teams in the past tried to use wireless sensors to pick up the very faint magnetic and electric fields near a wire, but such systems have required a complex alignment process since the fields in some places can cancel each other out.

The MIT device consists of an array of five sensors, each slightly offset from the others, and a calibration system that tracks the readings from each sensor and figures out which one is positioned to give the strongest signal.

The team has tested the system in various settings. An experiment at a military base revealed that large tents were being unnecessarily heated during winter months all day long, even though they were unoccupied for much of the time.

Another test installation in a domestic house found an anomalous voltage pattern that revealed a wiring flaw that caused some copper plumbing pipes to carry a potentially dangerous voltage.

The system is designed to protect the privacy of the occupants and not to disclose any information that could be used by third parties.

The software used to analyse the information allows users to focus on particular time segments that, for example, reveal when a refrigerator turns on and off and how often a water heater switches on and off during the day.

Once the system is developed into a commercial product it is thought it should only cost $25 to $30 per home.

"We're trying to lower the barriers to installation," said co-author John Donnal, adding that the non-contact sensor is easy enough to install by the users themselves. "It just goes on with a zip tie."