RE: [CAD_CAM_EDM_DRO] Re: Remember Mr. Bill's servo lite?

Hi Henrik:

I get that, but I do think that many(if not most) circuits do ground one side of the power supply, after it passes through the transformer.

And others will ground the center tap of the transformer.

Especially when you are talking high voltages, it may not be true that grabbing one side of a transformer winding that has no ground reference will not zap you. That is, after all, the reason that we DO ground the power mains. If it is not referenced to ground, you really have no idea where it is with relation to ground. Which is NOT the same thing as saying it will not hurt you if you touch it.


Andy


-----Original Message-----
From: CAD_CAM_EDM_DRO@yahoogroups.com [mailto:CAD_CAM_EDM_DRO@yahoogroups.com] On Behalf Of Henrik Olsson
Sent: Saturday, January 14, 2012 3:16 PM
To: CAD_CAM_EDM_DRO@yahoogroups.com
Subject: Re: [CAD_CAM_EDM_DRO] Re: Remember Mr. Bill's servo lite?

Hi Andy,
1) If you stand on the concrete floor or anything that's "ground" and grab
the wire which happens to be 120VAC you get buzzed.
2) If you stand on the concrete floor or anything that's "ground" and grab
one of the wires here (doesn't matter which one) nothing happens because
it's isolated from ground. You'd have grab *both* wires in order to get any
current flowing thru your body.

I don't know why you would ground one leg of the secondary of your isolation
transformer - if you do it's not isolated anymore...

Hope that makes at least a little bit of sense.

/Henrik.
_____

---Original message---


That;s what I don't get, and nobody seems capable of explaining it-they just
say "it is".

Take 2 scenarios:

1) A couple of wires plugged in to an AC outlet at 120VAC. One wire will be
"grounded", while the other wil be at 120VAC above ground.

2) A 120VAC isolation transformer, with the primary plugged in to the same
AC outlet, and the wires attached to the secondary.

Why is #1 necessarily more dangerous? I could think up scenarios, especially
if one side of the secondary is NOT grounded, where #2 would give more
chance of a dangerous electrical shock. But let's assume one side of the
secondary is #2 IS grounded. Why is it safer to have the isolation
transformer?

Andy Wander






[Non-text portions of this message have been removed]



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