Just so.
I do not know what the US conventions are, but here the term "double
insulated" is used to describe equipment that has the ac line (what we call
phase and neutral) applied to the motor, transformer or whatever, while the
case is of non conducting material that cannot become live even if there is
what we call an "earth fault"
I have built TX ht supplies using this philosophy. No metal chassis. Build
on wood, box with wood, albeit wood with plastic skin so that it looks
suitably technical.
73
end
Barry Kirkwood PhD ZL1DD
Signal Hill
66 Cory Road
Palm Beach
Waiheke Island 1240
NEW ZEALAND
www.waiheke.co.nz/signal.htm
end
Barry Kirkwood PhD ZL1DD
Signal Hill
66 Cory Road
Palm Beach
Waiheke Island 1240
NEW ZEALAND
www.waiheke.co.nz/signal.htm
----- Original Message -----
From: <i4jmy@iol.it>
To: <amps@contesting.com>
Sent: Wednesday, 03 January, 2001 11:08 PM
Subject: [AMPS] 3phases & Alpha
>
> A transformer doesn't care if an AC current is obtained by one leg of a
> 380V 3phase to neutral or in another way because the primary and
> secondary windings are electrically isolated.
> When a conflict occur it's because a circuit that's connected to the AC
> line is not isolated from it (or by original design or because of a
> failure) and a virtual zero point stops to be that a new path is
> created. In such situation, an extra separation transformer can fix the
> problem althoug when the involved power is rather big such solution is
> a bit bulky and finally not very cheap.
> Actually, to avoid GND/Neutral conflicts and for safety reasons, a
> circuit that's not isolated from the AC line (like most of domestic
> electrical appliances) should be at least isolated from ground
> (including the circuit virtual GND points) and confined inside a
> protected enclosure.
> A metal cabinet like that of an amplifier (that's also connected to
> antennas) must always be connected to GND and never connected to the AC
> line through a virtual zero point or directly to a neutral wire.
>
> 73,
> Mauri I4JMY
>
>
>
> --
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> Problems: owner-amps@contesting.com
>
>
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