In article ,
Eric wrote:


"Doug Miller" wrote in message ...

On 9/5/2011 4:00 PM, Eric wrote:


"m II" wrote in message ...

Dougy gets different water out of his garden hose than he puts in too! LOL

Need some basic electrical theory there Dougy or STFU.
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"Doug Miller" wrote in message ...
Inductive loads such as those presented by electric motors put the
return current slightly out of phase with the supply current. If the
amplitude of the phase difference exceeds 20mA, the GFCI trips.

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I would be sure Doug Miller was using an analogy and doesn't actually
believe currents could be different in a series circuit. Most electrical
people
should know better than that.

Cut the guy some slack.


There *is* a slight phase delay when the circuit supplies an inductive
load -- which means that during a time window measured in milliseconds
the currents *are* different. That can be enough to trip a GFCI.

Obviously, over anything but an extremely brief time period, the
currents are exactly the same.

Equally obviously, "m II" is in my killfile for good and valid reasons. :-)

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Sorry, but that "delay" theory is not correct.

"Those of you who think you know it all, are very annoying those who do."

You may have this confused with inductance where an inductive coil
electrical component exhibits a reluctance to current change.

Remember "current" flows through an inductive component and never into one
without returning to the source.

You know not that of which you speak.

There *is* energy in the magnetic field surrounding the inductor.
Just _where_ do you think that energy came from?

When power was applied some electricity went _into+ the device that did
_NOT_ come out as electricity *at*that*time*.

Similarly, when power is removed, some electricity comes out _after_ the
switch is opened. Just _where_ do you think that energy comes from?

hint, it is *stored* in the electromagnetic field.

There will never be a difference in current
in and out due to an inductive component or any component in an electrical
circuit.

*snicker*
Just where do you think the 'back emf' comes from when power is suddenly
removed from an inductor?

A changing voltage may create a phase lagged current through an inductor
(coil) but not a current phase lagged to itself, whereby current enters a
component but does not leave at. That would be impossible.

'Male bovine excrement' applies. You even stated one situation you call
'impossible'. To wit: 'A changing voltage through an inductor, may create a
phase-lagged current.' If you measure the *instantaneous* current _before_
and after the 'phase-shifting' device You *will* see different values.
Draw a sine-wave, measure the instantaneous (not 'peak', or 'mean) amplitude
at any given point during full cycle. Now measure the instantaneous amplitude
at a slightly different phase of the waveform. Unless the two points you
chose are symmetric around a maxima or minima of the waveform the
*INSTANTANEOUS* amplitude _will_ be different.

This is not what makes GFCI units trip from fan motors. Current leakage
faults to ground or other conductors causing a current "differential" (ANSI
Standard C37.2 - 87) is the only trigger.

And a *transient* phase-shift within a device _can_ cause a sufficient
'instantaneous' current difference (measured on opposite sides of the
phase-shift) to trip an old-style GFCI.