Horst: thank you very much for your answer. I'd like to comment it a
little.
1) From figure 5A on page 79c, I deduced I need an operational
insulation between two primary circuits, if they exist. But your
interpretation is possible. So, you have a operational insulation
between phase and neutral conductors, but bridging components between
them, like X capacitors, shall comply with stronger requirements than
those one for operational insulation. Well, I can accept it, although I
don't understand it very well. Moreover, I believe you also think that
no weaker requirement is accepted after the fuse.
2) I know the mentioned paragraphs of the standard, but I believe
it is not so clear the answer to my question. It seems like you agree
that working voltage in a transformer is depending on the phase. But
that may have a very expensive consequences. And I'm afraid nobody
thought in it while they wrote the standard.
3) I can read that # 2.3.5 deals with connection of SELV to other
circuits but please, try to think what it means and compare it with the
old fourth method for SELV circuits. Anyway that is only a comment, no
problem is in it.
4) I completely agree with you. "Earth is safe to touch. SELV is
safe to touch. Why shall there be any need for an insulation to protect
against electric shock?" But I'm afraid it is not written in the
standard. In fact, if a SELV circuit doesn't use the third method in a
class 1 equipment, I think that double or reinforce insulation is
necessary between primary and secondary through any way not including
the Protection Earth. But it is impossible to measure the electric
strength in those ways if you don't cut the Protection Earth way. In my
opinion, if I don't miss something, here we have a dark point in the
standard.
5)
Best regards
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De: Horst Dierich[SMTP:[email protected]]
Enviado el: domingo 26 de octubre de 1997 20:29
Para: [email protected]
Cc: EMC & Product Safety Forum
Asunto: Re: Questions about IEC/EN 60950
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