I need to clarify one thing I said below. That doesn't mean adding a variac set
up as a choke to the secondary HV side, it means to use a regular choke. I
don't think I'd want to handle a variac with 3000 Vac on it.
Best,
Will
*********** REPLY SEPARATOR ***********
On 3/5/06 at 11:11 PM Will Matney wrote:
>Bill,
>
>It's according to how you hook it up. If you connect one end of the
>variacs winding to the line, and the output to the wiper (going to the
>load), leaving the other side of the variacs winding unconnected, you have
>a variable choke. All it is, is a round iron core toroid, with magnet wire
>wrapped around it, and a wiper running across the bare magnet wire on the
>back side. If you use both ends of the coil (both to the line), and the
>wiper as out, you have a variable autotransformer. It will work either
>way. Generally, I always use them as a variable choke, and have ran
>several motors that way by converting the output AC to DC with rectifiers,
>and hooking that to a DC PM motor. All you have then is a big variable
>voltage DC supply. The old Hobart mig wire feeders worked the same way.
>That's how I powered my winding lathe too, and worked like a charm. In his
>case, he could use a choke to drop the line voltage some, however it will
>raise the current in the primary. He can use it o
> n the secondary side too providing the wire and paper in the choke can
>stand up to the HV (if it's insulated enough). Last he could buck the HV
>winding with a transformer that has a secondary of the right value. I
>personally don't like that route though because of the expense. A choke or
>variac is most likely cheaper than a transformer.
>
>Best,
>
>Will
>
>*********** REPLY SEPARATOR ***********
>
>On 3/5/06 at 7:49 PM Bill Turner wrote:
>
>>ORIGINAL MESSAGE:
>>
>>At 04:45 PM 3/5/2006, Will Matney wrote:
>>>That or a choke with enough inductive reactance to drop the voltage
>>>as that's all a variac is.
>>
>>~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>Can't believe you said that, Will.
>>
>>A variac is a transformer, not a choke. With a choke, the amount of
>>voltage drop depends on the amount of current drawn, while with a
>>variac it does not.
>>
>>73, Bill W6WRT
>>
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>
>
>
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