Re: Staco variac rating differences

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

Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>

Tesla list wrote:

> I've recently aquired another variac. I have two Staco variacs,
> 2510s, rated at 140v -at- 25 amps,120v input and has 5 terminals.

> The third, type 033-6565, the one I just got, is rated at 20
> Amps 0-180V, input 120V but has only 3 terminals. ???????

	Not uncommon.
	As noted previously, some devices provide two terminals
	at the same point for ease of wiring.  Others, specifically
	variac type, tap the coil a bit in from oneor both  ends,
	this allows them to provide outputs above the input.

> huh?

> Some physical characteristics:
 
> -The wire size is the same for all 3 variacs, #12.
> -All have the same brush, interchangable, with no apparent
> differences in size or shape. Totally alike.

> -The winding of the 033-6565 is about 3/4" taller than the
> 2510s but has the same diameter.

	This makes sense, as the 03306565 has the higher current
	rating, right?  If so, it would need a 'thicker' (larger
	cross section) hence 'higher' core.  There is enough
	margin in the wire and brush ratings to allow use of common
	bits in both designs.

> -The mounting hole "footprint" is also identical for the 2510
> and 033-6565.
> -Shaft sizes are alike at 1/2" diameter. The lengths are the
> same.

> I have several questions:
> 
> 1) How can the 033-6565 have 120 input and 180 out with only 3
> terminals? Or am I reading this the wrong way?

	Thats a puzzler.  No.  Wait.  If the 'hot END' is not
	brought out, yeah.  That Works:

                )
                )<-------160_____
        120_____)
                )
                )
                )
                )
                )
                )
        0/N_____)_________0_______

	(if my sketch survives)

	One terminal at the tap, nominal 120 in.
	One for the wiper. 0 to 180 out.
	One for neutral/0 in and out.

	Needs to be checked by inspection and ohmmeter!

> 2) Will the 033-6565 also handle 25 amps if kept to 120 volts?

	I'd think so.
 
> 3) Anyone know a good place to get brushes for Staco variacs?

	dunno...

	best
	dwp