Re: Variac Help

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

Original poster: "Sean Taylor" <sstaylor-at-uiuc.edu> 

Comments interspersed . . .

 > Original poster: BunnyKiller <bunikllr-at-bellsouth-dot-net>
 >
 >
 >
 > Tesla list wrote:
 >
 > >Original poster: "EMMETT SECREST" <secrest2032-at-msn-dot-com>
 > >I am in need of help on wiring of a Technipower 30A Variac.  I purchased
 > >it used and there are no instructions. I don't want to toast it as it was
 > >a little on the expensive side so your assistance is appreciated.  It has
 > >five connection points in this order;
 > >
 > >1  5  3  2  4
 > >
 > >1 = one end of the coil
 > >5 = between connection 1 and the center tap
 > >3 = center point of coil
 > >2 = between the center point and the end of the coil, point 5
 > >5 = the other end of the coil
 > >

Where is the wiper (movable) terminal?  It doesn't seem like this "variac"
has one from the description . . . and which of the 5's is supposed to be a
4? I'm guessing the second one by the ordering first given.

 > >This is a 130 volt single phase model that mounts inside a cabinet of
some
 > >type and does not have it's own enclosure.. My question is which points
 > >does the 120V supply connect to and which points are the output. Also
 > >where would the safety ground connect.
 > >
 > >Thanks in advance for your help,
 > >
 > >Emmett
 > >
 > >_
 > >
 >
 > Hi Emmett
 >
 > there are 3 different ways to hook up that style of variac....
 >
 > setup #1
 > input power  -  120VAC white to #1 lug      120VAC black to #4 lug
 >     green to ground on item to be powered and to case of variac
 >
 > output to item to be powered     white on #1 to item     black from #3 to
 > item       green variac case to item ground
 > this produces 120VAC in  and 0-120VAC out  at 30 amps output

Lead #3 would go do the "item" if that was the wiper of the variac, as
described, it just sounds like it's a center tap.

 > setup #2
 >
 > input power - 120VAC  white to Lug #1    120VAC black to #2 lug
 > green to variac case and item to be powered ground
 >
 > output to item to be powered    white on #1 to item    black from #3 to
 > item     green from case to item
 > this produces 120VAC in and 0-140VAC out  at 26 amps output
 >
 > setup #3
 >
 > input power - 120VAC white to Lug #1   120VAC black to Lug #5     green to
 > variac case and to item to be powered
 >
 > output to item to be powered   white on #1 to item   black from #3 to
 > item    green from varaic case to item to be powered
 > this produces 120VAC in and 0- 280VAC out   at 40% of variacs current
 > rating   in other words   12 amps or so

Be careful with this!!! I would not hook up any earlier tap than the second
to last one (terminal 2) to the 120 hot, unless the variac is specifically
rated at 240 volts (or higher . . .).  If you just hook this up, you could
be asking for trouble from saturation in the core.  It will heat up a lot,
as well as draw a lot of current!

Sean