You have probably answered this time and time again so please be gentle
with me and my first post. <G>
I have a generator that I want to power my 220 VAC Mig welder with and
I believe I have the wirig down pat with the black of my 10 guage
(stranded) to the X terminal ...and the white to the Y terminal ,,,and
green to the ground plug,, Is this correct??
Another "BIG concern" is earth grounding the generator while using it
as I want to keep it portable, on a small trailer as well as the Mig
welder, for welding on the run.. The generator says it has a "floating
neutral" and my concerns are not to burn up the Mig with the floating
ground and unclean power source.. What say yea gentlemen??
Let's first differentiate between a floating Neutral and a loose Neutral. A
loose Neutral is where there is no solid connection between the star-point
of the supply and the star-point of the load. Please note we said 'not
solid', and not "disconnected". 'Not solid' or 'loose' means any Neutral
that is not bonded with at least 2x phase and through this can lead to
imbalance on the load side.
A floating Neutral (star-point not bonded to Earth) is actually a floating
supply i.e. the whole supply can, as an entity, float from Earth. But we
need to cover one very important fact first.
Neutral can no longer be called Neutral! The term is given to this current
carrying conductor through it being 'neutralised' with Earth (and finally
Ground). As it can no longer hold on to Earth, it can no longer hold on to
the name usually given it. We therefore have to revert to the place where
this conductor is connected, this being the star-point of the transformer -
and we call it such.
There are two inherent 'dangers' with floating systems, although neither
'danger' damages equipment operating on the floating supply. As is, ships
have used this form of supply system very successfully for quite some time
now! But first,...
On 3-phase systems there is a tendency for the star-point and Phases to want
to 'balance out' based on the ratio of leakage on each Phase to Earth. The
star-point will remain close to 0V depending on the distribution of the load
and subsequent leakage (higher load on a phase usually means higher
If the supply is single phase then it is not uncommon to find the two
current carrying conductors balancing out at about half-supply voltage each
(on 230V this would mean 125V on both). Investigating leakage currents will
show that, if anything, a floating supply significantly reduces leakage
currents and therefore minimises damage to equipment through leakage via
On to the 'dangers'.
The first 'danger' is; Should a Live-Earth fault occur then it is highly
likely that NO protection will trip as there is no return for the fault
currents. The star-point will no longer be 0V and will now rise to 230V. The
second 'danger' is now present as only on a second fault will any protection
operate. This danger increases with 3-phase in that a Phase-Earth fault will
cause not only the star-point to rise to 230V, but the other phases will now
reach 400V. Should the second fault occur then this will occur at the said
400V rather than the 'designed for' 230V.
Equipment designed for 230V can usually withstand the 400V from Phase to
Earth without the danger of flash-over (note, not 'Phase-Neutral' which
still remains 230V). It may stress the insulation a little, but nothing is
likely to come of it (modern design specifications ensure that desigers are
aware of what's required).
Based on the above, it is safe to say that a floating 'Neutral' is not the
common cause of the equipment failure. Such damage is more attributable to
the fact that gen-sets are not clean sources of energy, and it was probably
one of a range of factors from high peak voltages to just simple overvoltage
or something similar. Or, simply, that someone forgot to connect the
Thanks for the quick reply as it is greatly appreciated...
Well then it sounds like I'm back to the drawing board if I want to use
the Mig welder with the gen. But it ain't worth frying a Linclon
175Plus MIG for the sake of mobility unless there is protection for
over and under voltage built into the unit..
Is there a reasonable way of cleaning/regulaiting the AC to keep from
over and or under voltage?? Just a stab in the dark my friend as I
have never been accused of not thinking. ;?)
I emailed Lincoln Electric with my question of using their MIG welder
with portable generator and they replied "You sure can. You will need
as much as 30 amps of 230 volt power."
Well if you see smoke coming from NW IL. then you know what happened..
trike Mike wrote:
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