Hi Pierre:
You did not state whether or not your secondary circuit
is intended to be SELV or not. This is critical to your
choice of capacitor. However, you did ask whether the
circuit is equivalent to reinforced insulation, so I
assume that your secondary circuit is SELV.
By definition (IEC 60384), an X capacitor is "of a type
suitable for use in situations where failure of the
capacitor... would not lead to danger of electric shock."
A Y capacitor is "of a type suitable for use in situations
where failure of the capacitor could lead to danger of
electric shock."
So, if your secondary circuit is not SELV, then you can
use an X capacitor (or any other suitable capacitor). The
advantage of X capacitors over other capacitors is that
X capacitors are specifically designed to withstand
impulse voltages superimposed on the mains voltage.
If your secondary circuit is SELV, then you MUST use a
Y capacitor.
There are 4 classes of Y capacitors:
Y1 (250 V rms, 8 kV impulse) is equivalent to double
or reinforced insulation.
Y2 (250 V rms, 5 kV impulse) is equivalent to basic
insulation.
Y3 (250 V rms, 0 kV impulse) is equivalent to basic
or supplementary insulation.
Y4 (150 V rms, 2.5 kV impulse) is equivalent to basic
or supplementary insulation.
You can use 1 Y1 cap or 2 Y2 caps in series between mains
and SELV.
Best wishes for the New Year!
Rich
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