Re: [TCML] Variac Problem!

[dave pierson <dave_p@xxxxxxxxxxx>]

> I am using two 40 Amp variacs, one to limit the current and one as
> voltage control. I have wired them up as follows: The current control
> variac is in series with the input of the voltage variac (this variac
> has been cut to act as a variable inductor, 0.4 to 27.8mH) and the
> other end of the voltage variac is connected to the neutral; the brush
> is the output to my transformer. The problem is that when I turn on
> the mains, the voltage variac makes a buzzing sound (obviously mains
> frequency) and the ammeter is reading 10 Amps.

   Which ammeter, where?
   How is the 'variable inductor' set?
   What load, if any on the 'voltage variac'?
 
> I think that the core is saturating.
   Which core?  The 'voltage variac'?

> However, if I remove the current control variac and
> connect the input of the voltage variac to another variac controlled
> power supply, so that the input to the variac in question is supplied
> via the brush output of the power supply variac
   How is the 'power supply' variac set?

> there is only a quiet hum from the variac
   Which 'the variac'?

> and the ammeter is reading about 0.5 Amps.
   Which 'the ammeter', where?

> What is wrong and how do I fix the problem?
   Is anything 'wrong'?
 
   (Yes: thats a lot of questions.  It can be hard to
   troubleshoot by text, without diagrams.)

   Might try using the 40 A 'inductor variac'
   
   A 40A variac has a lowish 'impedance' (since its
   designed for high current.).  It may not be
   limiting as anticipated.

best
 dwp
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