Why do Arc-Welders cause the Wheels of old House-Meters, to Spin Backwards ?

[gyulasun]

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As I see it, under certain circumstances an Arc welder might just create a current large enough in opposition to the incoming current and this is what is seen.
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Yes and as an addition I think that the negative resistance created by the electric arcs (a characteristic in their VI curve) may cause oscillations in the welding transformer and this can transform back to the mains through the primary coil. These oscillations my occasionaly exceed the mains voltage amplitude and behaving as a voltage source overriding the mains incoming amplitude, thus causing the large enough 'backwards' current flow.

Gyula

[allcanadian]

@Grumage

As I see it, under certain circumstances an Arc welder might just create a current large enough in opposition to the incoming current and this is what is seen. With the phasing out of electromechanical meters being implemented more and more this phenomenon will become the stuff of legend.

I would agree, few understand that we are not actually connected to the grid, we are connected to a fairly large line transformer which is connected to the grid. If a large enough disturbance of sufficient quality coupled to the line transformer secondary and the line capacitance then any number of supposedly strange things might occur.


I read of one instance where an induction motor acting as a generator could supposedly generate full power at under 1/4 of the rated RPM. As we know an induction generator uses reactive power from the grid at 60 Hz to energize the stator coils and the armature must be above this frequency to produce a phase differential to generate power. It was theorized the induction generator may have coupled to the line transformer forming an LCL circuit allowing it to operate at a very much lower RPM while still generating full power.


AC

[Turbo]

If your wall voltage is 120 V, and you raise the voltage on your side to 200 V then, from the meters perspective, it will look as if the power is running back into the 'grid'.
I say look as if because it's a trick, the power comes from the same source, it's just switched in a different manner(unless you have your own source like solar, of course),there are devices that charge up capacitors in parallel just to discharge them in series back into the source, just to fool the meter.
Of course the same can be achieved with inductive equipment like for example welders.

[Magluvin]

If your wall voltage is 120 V, and you raise the voltage on your side to 200 V then, from the meters perspective, it will look as if the power is running back into the 'grid'.
I say look as if because it's a trick, the power comes from the same source, it's just switched in a different manner(unless you have your own source like solar, of course),there are devices that charge up capacitors in parallel just to discharge them in series back into the source, just to fool the meter.
Of course the same can be achieved with inductive equipment like for example welders.

Just seems odd. If one phase of AC is pushing current in and the other phase pulling current out, and the meter flows the same direction for each, how would the wheel determine whether current is going in or out in order to reverse direction?

Going to read the pdf

Mag

[minnie]

   YouTube "Three phase meter running backwards".