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    Weird measurements

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    corndog71

    Posts : 444
    Join date : 2013-03-19
    Location : It can get windy here

    Weird measurements

    Post by corndog71 on Fri Jun 10, 2016 9:48 pm

    So I finally got a Kill-a-watt and it's pretty cool.  My main rig is drawing around 2.6 amps at idle.  

    One thing that surprised me was that with my fluke 77 meter I would typically measure 125vac from the wall.  Tonight the KAW shows 118vac.  I double checked it from my meter and it shows 120vac (L-N).

    My ST120 is on a variac and I wanted to confirm the output of it so I initially checked from L-Ground and got 146vac!  I kinda freaked and turned it down to 117vac.  Then I checked from L-N and only measured 47vac.  Then I looked at the amp and noticed the filaments were barely glowing so I turned it back up to 117vac (L-N).  I went back to measure L- ground and now show 155vac!  Fascinating.  

    I also plugged one of those polarity checkers into the wall and my assortment of filtered power strips and they all checked out correctly wired however when I plugged it into the variac I just get the red led lit.  scratch  I guess this is just how a variac works.

    Kentley

    Posts : 295
    Join date : 2015-03-06
    Age : 64
    Location : Worcester, MA

    Re: Weird measurements

    Post by Kentley on Sat Jun 11, 2016 12:58 am

    Sounds like your variac is very-ac. As in cooked.
    The Fluke is likely the steadiest measure, providing its batteries are full, and leads clean.
    If your incoming AC is above 118 VAC you might try a rectifier switch. See other threads for advice.
    When you have multiple devices "regulating" your power, and they disagree, best to simplify. Maybe it's just the wind...

    10-E-C

    Posts : 75
    Join date : 2014-02-12
    Age : 62
    Location : upper east tn

    Re: Weird measurements

    Post by 10-E-C on Sat Jun 11, 2016 6:14 am

    You may get different readings from G - L and N - L if the ground is isolated from neutral in your equipment. I saw this all the time in old equipment (47vac) where where the neutral isn't bonded to ground.

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