Re: How are 240 VAC variacs made?

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: Finn Hammer <f-h-at-c.dk> 



Tesla list wrote:
>Original poster: "Hydrogen18" <hydrogen18-at-hydrogen18-dot-com>
>How are 240 VAC variacs made? Since the feed you get from your pole pig is
>240 VAC center tap, are they really 2 120 VAC variacs with linked shafts and
>aligned rotor contacts? I dont see how you get it to work if it wasnt
>because the rotor contact would be a potential to either side of the line
>but would really be pulling from only one half on the transformer and
>essentially feeding it with 120 VAC although it would be able to deliver
>0-240 VAC.
>---Eric
>

Eric

There are 2 popular ways to make these variac`s, one for the dumpster 
diver, another for the pro.

The pro just orders a 240/280volts variac, which has enough windings to 
sustain the voltage.

The scrounger hauls 2 120 volts variacs home and connects them like this:

            +----------9 <----------------
            |          9            ^
            |          9            |
            |          9            |
            |          9            |
            |          9          0-280V
     -------)----------9            |
    ^       |          9            |
    |       |          9            |
    |       |                       v
    |       +----------9 <-----------------
   240V                9
    |                  9
    |                  9
    |                  9
    v                  9
    -------------------9
                       9
                       9

The "9`s" are the windings.

If morale is high, he connects them on the same shaft, but this is not 
necessary.


Cheers, Finn Hammer