Hi Ed:
> First of all the "floating secondary ground" (if not connected
> directly to earth) should be treated as part of the secondary circuit
> which in many cases will require reinforced insulation to the primary
> circuit according to the working voltage measured.
There are two issues here:
(1) Is the secondary circuit, pole-to-pole, a hazardous
voltage?
(2) Is one pole of the secondary circuit accessible?
With respect to (1): In this case, see my paper:
http://www.ewh.ieee.org/soc/emcs/pstc/tech-spk.htm
This paper describes how to achieve protection against
electric shock due to the voltage of the secondary
circuit.
With respect to (2): In this case, protection against
electric shock *from the mains* must be provided by
reinforced insulation (or equivalent) between the primary
and secondary.
> Next, in most applications, the secondary circuitry can be cap coupled
> to earth ground and does not require basic insulation spacings for a
> primary circuit.
Agreed -- PROVIDED at least basic insulation is between
the mains and the secondary circuit. If not, then the
capacitor from the secondary to ground must be a Y cap.
Best regards,
Rich
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