DC current through a domestic supply meter

[terryS]

These questions came up through some discussion on another technically/
scientifically unrelated news group ................... ?

1) What happens if a DC current** flows through a domestic/residence
supply meter?

2) Would it be any different if the meter was the older 'spinning
disc' type or the more modern 'digital' display type?

........................................................................................................................

1) Meter might register impulses of current in one direction only?
Also since current flow would be only during a half cycle only half
the energy would be transferred? AC motors would not work and anything
with a transformer would output a weird waveform of half voltage or
less?

2) Unknown?

PS. ** Hard to understand in what context the question was based!
Gather that in fact the current 'might' be a 'mixture' of domestic AC
and some DC (e.g. welding, without an interposing transformer ???). So
that an AC current could have a DC bias in one direction or
other?????
All very puzzling!

 

[whit3rd]

On Dec 13, 8:16 am, terryS <tsanf...@nf.sympatico.ca> wrote:

These questions came up through some discussion on another technically/
scientifically unrelated news group ................... ?

1) What happens if a DC current** flows through a domestic/residence
supply meter?

It gets measured, and you pay for it. The pole-pig transformer that
connects to your house always outputs zero DC voltage, but
that doesn't stop your house's appliances from sucking more
current on the positive side of the AC wave, i.e. DC current.

2) Would it be any different if the meter was the older 'spinning
disc' type or the more modern 'digital' display type?

No. The display notwithstanding, both meter types do a true
power measurement.

 

[Bob Masta]

On Sun, 13 Dec 2009 13:46:46 -0800 (PST), whit3rd
<whit3rd@gmail.com> wrote:

On Dec 13, 8:16=A0am, terryS <tsanf...@nf.sympatico.ca> wrote:
These questions came up through some discussion on another technically/
scientifically unrelated news group ................... ?

1) What happens if a DC current** flows through a domestic/residence
supply meter?

It gets measured, and you pay for it. The pole-pig transformer that
connects to your house always outputs zero DC voltage, but
that doesn't stop your house's appliances from sucking more
current on the positive side of the AC wave, i.e. DC current.

2) Would it be any different if the meter was the older 'spinning
disc' type or the more modern 'digital' display type?

No. The display notwithstanding, both meter types do a true
power measurement.

The electromechanical "spinning disc" uses
induction to produce eddy currents in the disc. I
don't think it would spin at all with DC applied.

See http://en.wikipedia.org/wiki/Electricity_meter

Best regards,
Bob Masta

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[Phil Allison]

"Bob Masta"

The electromechanical "spinning disc" uses
induction to produce eddy currents in the disc. I
don't think it would spin at all with DC applied.

** Such use two inputs - voltage AND current.

No matter what load is applied, the voltage always remains AC.

I doubt the instrument will be out by much if someone uses a diode in series
with the load.



....... Phil

 

[Jasen Betts]

On 2009-12-14, Bob Masta <N0Spam@daqarta.com> wrote:

On Sun, 13 Dec 2009 13:46:46 -0800 (PST), whit3rd
whit3rd@gmail.com> wrote:

On Dec 13, 8:16=A0am, terryS <tsanf...@nf.sympatico.ca> wrote:
These questions came up through some discussion on another technically/
scientifically unrelated news group ................... ?

1) What happens if a DC current** flows through a domestic/residence
supply meter?

It gets measured, and you pay for it. The pole-pig transformer that
connects to your house always outputs zero DC voltage, but
that doesn't stop your house's appliances from sucking more
current on the positive side of the AC wave, i.e. DC current.

2) Would it be any different if the meter was the older 'spinning
disc' type or the more modern 'digital' display type?

No. The display notwithstanding, both meter types do a true
power measurement.

The electromechanical "spinning disc" uses
induction to produce eddy currents in the disc. I
don't think it would spin at all with DC applied.

some use eddy currents to drive the disc (like the one on wikipedia)

others use a motor to drive the disc and a
permanent magnet to brake the disc. (voltage provides the field,
current flows through the rotor)