[Test-Equipment] Mains protection for work bench test equipment?

[Brooke Clarke]

Hi John:

I think the prior post that mentioned Sola transformers was intended to refer 
to their ferro resonant type.  These have an extra winding that has a capacitor 
across it and resonates at the line frequency.  It's acting as a narrow pass 
filter, voltage regulator and does suppress spikes.  It also fills in small 
dropouts or brownouts.

For the basic Ferro Reasonant transformer see patent 
http://www.google.com/patents?id=gAsCAAAAEBAJ&pg=PP1&dq=2143745
by Joseph Sola
and for one that also includes a spike suppression circuit around the capacitor 
see: http://www.google.com/patents?id=gAsCAAAAEBAJ&pg=PP1&dq=3938033

Have Fun,

Brooke Clarke
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J Forster wrote:
> Isolation transformers, with ultra low primary to secondary caacitance, will
> help a lot with common mode spikes, but all transformers just pass differential
> mode spikes. Core saturation does not help  because the the VdT integral is not
> large enough in most spikes to saturate the core.
> 
> Best,
> -John