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Energy Saving Devices?

  1. Mar 8, 2010 #1
    Dear Experts,

    I would like to solicit your comments about energy saving devices (electric consumption reducer) which is being advertised in malls, streets, tv, etc.

    Here’s my story:

    Recently I’ve attended a Science Fair Competition and there’s a man claiming that the device he made can save electric energy consumption. The instruments he showed to us are power source (ac), home electric meter (dial type), a blower, and, the claimed energy saving device. At first, he connects the blower into the electric meter which is connected to a power source. The disc of the electric meter rotates at constant speed (I think about 4 sec/turn). But when he plugged the blower to his energy saving device, the disc rotation suddenly slowed down and at a certain time, it stops! The blower still operates at good. He just showed us what’s inside the energy saving device and it’s composed of an IC circuit, capacitors, diodes, etc.

    My questions are:

    1. Is it true that there are certain device can stop the rotation of the disc?
    2. Are all these energy saving device truly saves your electric energy consumption? and
    3. Is there no harmful effects in your appliances, etc.?
  2. jcsd
  3. Mar 8, 2010 #2


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    Science Advisor
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    2017 Award

    Sounds like theft to me. That's assuming it actually works. I guess liquid nitrogen or dry ice could gum up the works of a rotating disc meter. I wonder what this "blower" was supposed to be blowing into the meter.
  4. Mar 8, 2010 #3
    The only household "energy saving" circuit I have ever seen that worked is a power-factor corrector circuit for induction motors (like in refrigerator). A lightly-loaded induction motor has a low power factor. The power factor can be increased by reducing the motor ac voltage using a triac. When the reactive current is reduced by reducing the ac voltage, the I2R losses in the motor windings are reduced, with only a small reduction in RPM. I built one, and determined that after a few seconds, the refrigerator ac voltage dropped from 120 volts to ~90 volts (on a 1966 vintage refrigerator). If the power factor was increased more, the motor began to draw more current. (This might not work on new refrigerators with microprocessors).

    A good lab (or home) experiment is to plug a 1/4-HP induction motor (with no load) into a Variac, and find the voltage that minimizes the wall-plug real power.

    Bob S
  5. Mar 8, 2010 #4
    One of the things that I learned in college, is << illegal activity info deleted by berkeman >>
    Last edited by a moderator: Mar 8, 2010
  6. Mar 8, 2010 #5


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    Staff: Mentor

    Let's all remember that illegal activities are not discussed here on the PF.
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