Re: [TCML] Variac

[Yurtle Turtle <yurtle_t@xxxxxxxxx>]

If you don't need to go above 20 amps, you can find an ammeter that doesn't need a shunt or a CT. I have one, but don't want to part with it.

Adam

--- On Fri, 10/24/08, David%20Rieben <drieben@xxxxxxxxxxx> wrote:

> From: David%20Rieben <drieben@xxxxxxxxxxx>
> Subject: Re: [TCML] Variac
> To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
> Date: Friday, October 24, 2008, 12:07 PM
> Hi Jay, 
> 
> 
> 
> There's no need to try to "make" a current
> tansformer 
> 
> as they are quite available for a pretty reasonable price,
> 
> 
> especially when they show up on ebay. One thing to keep 
> 
> in mind is that they are nearly always rated at X:5,
> meaning 
> 
> that most AC ammeters that have a full scale deflection 
> 
> of more than 0 - 50 will require a MATCHING current 
> 
> transformer in order to give the correct current mea- 
> 
> surement - i.e. a 50:5 current transformer would be 
> 
> required for a 0 - 50 amp ammeter to give a correct 
> 
> measurement, a 150:5 current transformer for a 0 - 
> 
> 150 amp scaled meter, ect. Many higher current scaled 
> 
> AC ammeters will come with a matching current trans- 
> 
> former when purchased new and as far as I know, all 
> 
> AC ammeters that measure over 50 amps will have a 
> 
> 5 amp full scale deflection and therefore requre a cur- 
> 
> rent transformer to give a correct current measurement. 
> 
> 
> 
> David Rieben 
> 
> 
> 




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