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Legacy and recent electricity supply and metering.

 
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Catweazle



Joined: 17 Feb 2008
Posts: 2550
Location: Little England, over the hills

PostPosted: Wed Jun 17, 2020 9:17 pm    Post subject: Reply with quote

adam2 wrote:
Take great care, dangerous voltages and dangerous moving parts are involved.
Think very carefully indeed before connecting else to this crude AC supply.


Don't worry Adam, I'm a time-served electrician, it was a long time ago but electricity remains unchanged Laughing
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adam2
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Joined: 02 Jul 2007
Posts: 8065
Location: North Somerset

PostPosted: Thu Jun 25, 2020 3:14 pm    Post subject: Reply with quote

Catweazle wrote:
adam2 wrote:
Take great care, dangerous voltages and dangerous moving parts are involved.
Think very carefully indeed before connecting else to this crude AC supply.


Don't worry Adam, I'm a time-served electrician, it was a long time ago but electricity remains unchanged Laughing


Electricity has changed a lot.
Fresh electricity is red, and used up electricity being returned for recycling is black. This used to be reflected in the colours of the wires, but not anymore.
Electricity has get much more dangerous, hence the increasingly complex regulations to protect us from this danger.
The insulating qualities of air have declined very significantly, new electric railways now require much greater clearances than used decades ago.
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Catweazle



Joined: 17 Feb 2008
Posts: 2550
Location: Little England, over the hills

PostPosted: Thu Jun 25, 2020 3:31 pm    Post subject: Reply with quote

adam2 wrote:
Catweazle wrote:
adam2 wrote:
Take great care, dangerous voltages and dangerous moving parts are involved.
Think very carefully indeed before connecting else to this crude AC supply.


Don't worry Adam, I'm a time-served electrician, it was a long time ago but electricity remains unchanged Laughing


Electricity has changed a lot.
Fresh electricity is red, and used up electricity being returned for recycling is black. This used to be reflected in the colours of the wires, but not anymore.
Electricity has get much more dangerous, hence the increasingly complex regulations to protect us from this danger.
The insulating qualities of air have declined very significantly, new electric railways now require much greater clearances than used decades ago.


Some farmers around here tip the used electricity straight into the ground to reduce wear-and-tear on the electricity meters.
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adam2
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Joined: 02 Jul 2007
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Location: North Somerset

PostPosted: Thu Jun 25, 2020 5:52 pm    Post subject: Reply with quote

With a standard UK supply system, nothing is gained by returning the used up electricity directly to the ground.
The electricity meter measures the current in the live wire and does not "know" what happens to it afterwards.

In France however some supply systems had BOTH sides of the supply live, but the meter only registered the current in ONE wire.
Free electricity could be obtained between the unmetered live and earth.

The earth leakage circuit breaker was allegedly invented by French utilities to stop this sort of thing.
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kenneal - lagger
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Location: Newbury, Berkshire

PostPosted: Sat Jun 27, 2020 3:32 pm    Post subject: Reply with quote

I vaguely remember my genny generating at +115V and minus 115V on the positive and negative sides to give a 230V supply.
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adam2
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Location: North Somerset

PostPosted: Sat Jun 27, 2020 4:01 pm    Post subject: Reply with quote

kenneal - lagger wrote:
I vaguely remember my genny generating at +115V and minus 115V on the positive and negative sides to give a 230V supply.


Yes, not strictly positive and negative unless it was direct current, but many smaller generators use a single 230 volt winding with a center tap so as to give a choice of 115 volts or 230 volts.

Historically, many parts of Europe used a 3 phase, 4 wire system with 127 volts phase to neutral and 220 volts phase to phase.
A few such supplies probably remain in use, but most will have been changed to 220 volts phase to neutral and 380 volts between phases.

Dishonest persons with a 220 volt supply derived from a 127/220 volt system found that the KWH meter only measured the current in ONE of the supply wires. Free electricity could be obtained by connecting between the unmetered side of the supply and an earth rod, or metal fence.
This stolen electricity would only be at 127 volts, but still useful.
Sales of 125 volt lamps were substantial in some areas despite consumers having 220 volt supplies.

No advantage whatsoever will be gained on any standard UK supply by such tricks.
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fuzzy



Joined: 29 Nov 2013
Posts: 1356
Location: The Marches, UK

PostPosted: Sun Jun 28, 2020 1:12 pm    Post subject: Reply with quote

You can make a UK standard electric meter run back with a 'bucking' transformer. You need a few 100 watt normal transformer - more easily with side by side secondary/primary windings because you need to remove the secondary copper and wind a few turns of heavy copper wire around the laminate instead of the secondary. This then connects across the meter live in and out. AFAIK, the only illegal part is making one connection before the meter. The primary runs just like a normal mains primary, live to neutral eg a 3 pin plug. The secondary needs to be 1 way round - to give a slightly higher voltage after the meter reducing current through the sense coil.

No one should try this of course.
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Catweazle



Joined: 17 Feb 2008
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Location: Little England, over the hills

PostPosted: Sun Jun 28, 2020 2:40 pm    Post subject: Reply with quote

No idea how or if it works, farmers are a superstitious lot. They mostly have 3 phases direct from a pole mounted transformer.

I have 3 electricity meters myself, in different buildings, I wonder if they're on different phases. Not that I need 3 phase, I use inverters to convert single to 3 phase to run machinery.
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kenneal - lagger
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Joined: 20 Sep 2006
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Location: Newbury, Berkshire

PostPosted: Sun Jun 28, 2020 8:39 pm    Post subject: Reply with quote

fuzzy wrote:
You can make a UK standard electric meter run back with a 'bucking' transformer. You need a few 100 watt normal transformer - more easily with side by side secondary/primary windings because you need to remove the secondary copper and wind a few turns of heavy copper wire around the laminate instead of the secondary. This then connects across the meter live in and out. AFAIK, the only illegal part is making one connection before the meter. The primary runs just like a normal mains primary, live to neutral eg a 3 pin plug. The secondary needs to be 1 way round - to give a slightly higher voltage after the meter reducing current through the sense coil.

No one should try this of course.


I thought I was getting lost in LJ's jargon until I read that above!!! And I did OND Engineering, oh 55 years ago now! Maybe that's why it is all so baffling!
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fuzzy



Joined: 29 Nov 2013
Posts: 1356
Location: The Marches, UK

PostPosted: Mon Jun 29, 2020 2:05 pm    Post subject: Reply with quote

Basically the few turns of copper suck the current past the meter like a salmon run on a river weir. Because there is probably ~ 1volt more after your meter ie in your house wiring, than the supply going into the meter live, the meter counts back. ie it normally expects your house voltage to be a slightly lower voltage than the meter input, not higher. The transformer doesn't supply the 230V of household mains - that would require enormous output - just +1 volt extra [approx guess]
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kenneal - lagger
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PostPosted: Tue Jul 07, 2020 3:04 pm    Post subject: Reply with quote

This flywheel in Scotland is being touted as an answer to the problem of too little spinning mass.
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