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More efficient lighting thanks to magnetic energy recovery switch

Sept. 24, 2010
A power factor control circuit from the University of Tokyo boosts the efficiency of lighting at a U.S. Naval facility.

The Office of Naval Research branch in Tokyo has worked with researchers from the Tokyo Institute of Technology to install what's called a Magnetic Energy Recovery Switch (MERS) that saves on light bills.

A presentation on the basics of the MERS device, http://www.ryutu.inpit.go.jp/seminar_a/2010/pdf/25/A2/A2-02.pdf

The MERS is basically a four-transistor active snubber circuit that effectively synthesizes a tunable capacitor. When hooked up with an external inductor, one of the uses of the device is to adjust circuit power factor. When used with fluorescent lamps, the MERS can function as a dimmer.

ONR Global funded a series of experiments at Tokyo's Hardy Barracks Installation earlier this year to evaluate how well the MERS lighting controller saved energy. Tests used overhead fluorescent lights. Installing the MERS circuits resulted in a 39% savings in energy in the best case. Though the details of the tests are sketchy, it looks as though they involved fluorescent lights with magnetic ballasts, so the variable capacitance of the MERS interacts with the light ballast inductance to form a sort of variable tank circuit. It is not clear whether or not the MERS device would work the same way with an electronic lamp ballast.

The Navy wants to run the same experiment in the entire Hardy Barracks Installation so that it extends into areas that include a break room, printing press room, laundry room, gymnasium and several offices.

More info:

MERSTech, http://www.merstech.com/en/technology.html

ONL announcement of the MERS experiement, http://www.onr.navy.mil/Media-Center/Press-Releases/2010/Magnetic-Energy-Recovery-MERS.aspx

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