Re: Isolation transformer

On Sat, 05 May 2007 09:54:23 -0400, default <default@xxxxxxxxxxxxx>
wrote:

On Sat, 05 May 2007 13:42:06 +0900, spamfree@xxxxxxxxxxx wrote:

I'm trying to find out why these are used as safety precautions in
servicing mains connected equipment. Seems to me that not being
electrically connected to the mains is a moot point. Surely the pole
transformer isolates me from the generating dynamo at the power
station, but my outlet can surely still kill me. Induced currents can
surely be as dangerous as directly conducted currents?

Wikipedia states under this heading:

"In electronics testing, troubleshooting and servicing, an isolation
transformer is a 1:1 power transformer which is used as a safety
precaution. Since the neutral wire of an outlet is directly connected
to ground, grounded objects near the device under test (desk, lamp,
concrete floor, oscilloscope ground lead, etc.) may be at a hazardous
potential difference with respect to that device. By using an
isolation transformer, the bonding is eliminated, and the shock hazard
is entirely contained within the device."


Why would things connected to the same ground have dangerous potential
differences from that ground?
Could some kind soul 'splain this to me, please?

jack

The wikipedia explanation is excellent, what part are you having
trouble understanding?

An isolation transformer makes electrocution less likely since there
are grounds all around and you are more likely to contact ground with
one part of the body while touching a live circuit in whatever you are
working on. You can still be electrocuted but it helps your chances
of staying alive.

But you haven't actually said HOW it helps, have you?
I'm trying to understand how an IT helps with grounded chassis
equipment and polarised three pin plugs to the mains. jack
.

Relevant Pages

  • Re: Isolation transformer
    ... electrically connected to the mains is a moot point. ... "In electronics testing, troubleshooting and servicing, an isolation ... transformer is a 1:1 power transformer which is used as a safety ... chassis of a TV, you will likely see sparks fly. ...
    (sci.electronics.basics)
  • Re: Isolation transformer
    ... "In electronics testing, troubleshooting and servicing, an isolation ... transformer is a 1:1 power transformer which is used as a safety ...
    (sci.electronics.basics)
  • Re: really dumb question re direct line powering and safety
    ... audio transformer per each jack so features such as FX loop and DI ... type tasks and are not up to the requirements of mains isolation. ... encase the amp in a plastic cabinet or something and take great care ...
    (alt.guitar.amps)
  • Re: Isolation transformer
    ... electrically connected to the mains is a moot point. ... "In electronics testing, troubleshooting and servicing, an isolation ... transformer is a 1:1 power transformer which is used as a safety ... you just won't get shocked by touching one hand to the chasis. ...
    (sci.electronics.basics)
  • Re: Powerstat and transformer for variable voltage output
    ... the mains. ... the transformer, you would need to connect the normally "Neutral" side ... of the Powerstat to the "Hot" side of the mains, ... I would not do this without an additional isolation ...
    (sci.electronics.design)
Quantcast