Re: [TCML] Variac

["Phillip Slawinski" <pslawinski@xxxxxxxxx>]

I also agree with David on this.  The variac will take 23A all day long, no
problem.  I can say from experience that if you try and push two or three
times rated current through a variac it will not be too 'happy'.  My variac
can attest to this, the enamel on the wire is charred and cracking in some
places from when I ran 4kVA throuh it without any sort of cooling [Variac is
a 2kVA unit].  The variac still works perfectly, but I'm sure if I kept
pushing that much through it, the unit would have failed.

On Thu, Oct 30, 2008 at 07:48, bunnykiller <bunnikillr@xxxxxxx> wrote:

> Hey David...
>
> You are correct about running the 23 amps but I did forewarn him that more
> than 23 amps will be a problem ;)
>
> Scot D
>
>
> David Rieben wrote:
>
>  Hi Scot,
>>
>> You wrote:
>>
>>
>>  Hey Jay..
>>>
>>
>>
>>  The unit is rated for 22.5 amps current capacity, in other words it will
>>> handle a current of 22.5 amps max thru it to the load it is supplying. If
>>> you were to put a load on the variac that can draw more than 23 amps, the
>>> Variac will overheat and smoke and eventually die...  most of the times,
>>> variac failure occurs where the wiper ( brush) is in contact with the
>>> windings, either the brush arcs out or the windings melt and break.
>>>
>>
>>
>> In principle, this is definitely true. However, in reality, since variacs
>> are
>> typically rated very conservatively at a 100% duty cycle, I would ima-
>> gine that it would take a really looong time to cause a 22.5 amp "rated"
>> variac to fail by running 23 amps continuously through it. :^) It
>> certainly
>> should not fail running this current level through the relatively short
>> runs
>> of coil firing.
>>
>>
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