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Kill-a-Watt fun

Discussion in 'Home Power and Microgeneration' started by [email protected], May 8, 2007.

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  1. Guest

    Power factor correction caps at 120 volts:

    PF .5 .6 .7 .8
    watts

    100 31.9 24.6 18.8 13.8
    200 63.8 49.1 37.6 27.6
    300 95.7 73.7 56.4 41.4
    400 127.6 98.2 75.2 55.3
    500 159.5 122.8 94 69.1
    600 191.4 147.4 112.8 82.9
    700 223.3 171.9 131.5 96.7
    800 255.2 196.5 150.3 110.5
    900 287.1 221 169.1 124.3
    1000 319 245.6 187.9 138.2
    ^ m i c r o f a r a d s ^

    Power factor correction caps at 277 volts:

    PF .5 .6 .7 .8 (uncorrected)
    watts

    100 6 4.6 3.5 2.6
    200 12 9.2 7.1 5.2
    300 18 13.8 10.6 7.8
    400 24 18.4 14.1 10.4
    500 29.9 23 17.6 13
    600 35.9 27.7 21.2 15.6
    700 41.9 32.3 24.7 18.1
    800 47.9 36.9 28.2 20.7
    900 53.9 41.5 31.7 23.3
    1000 59.9 46.1 35.3 25.9
    ^ m i c r o f a r a d s ^

    C = 2653xPxsqrt(1-PF^2)/(V^2*PF) microfarads

    Cap values are proportional to power. For instance, the table above shows
    2.6 uF for 100 watts with a 0.8 power factor before correction and about
    26 uF for 1000 watts with a 0.8 power factor before correction.

    The $199 TES 3079K clamp-on meter from Optimum Energy works
    up to 600 V and 600 kW and also measures capacitance...

    Nick
     
  2. Guest

    Sure. C = 2653x800xsqrt(1-0.6^2)/(120^2*0.6) = 196.5 microfarads
    You might parallel smaller caps. This won't save much residential
    grid-tie money.
    You might want to shoot for a bit less than 1, since that makes resonance.
    One Sprague engineer said he thought that would not be a problem.
    A series choke might lessen worries about fusing switch contacts.
    Hey, try it :) Then move your swamp cooler indoors and turn it on
    with a room temp thermostat when the indoor temp reaches 80 F and
    turn on a small exhaust fan when the indoor RH reaches 56% :)

    Nick
     
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