Analogue Electricity Meters.
 

Split from this thread:-

https://www.vintage-radio.net/forum/...d.php?t=142920


I have seen somewhere (!) a vintage meter that runs on a sealed ball bearing system in which the more power that is used the more expensive is the power. The current being taken tilts the device holding the ball bearings putting another ball bearing in the collector/measuring device. The more current the more ball bearings fell.

Re: Analogue Electricity Meters.
 

I've heard of old electricity meters being fiddled by fixing a powerful magnet to them to slow down the rotating disc. Sometimes this would cause the meter to overload and cause a fire.

Re: Analogue Electricity Meters.
 

The wheels were aluminium in old meters so a magnet wouldn't affect them. I have seen devices consisting of a couple of turns of wire wrapped around the primary of a stripped down mains transformer. The extra winding was then placed with it's ends shoved up the outer meter connections. Connecting one way around stopped the wheel and connecting the other way around wound the wheel backwards.

I hope it's ok to mention this on here as afaik such analogue meters are well past their sell by date.

Re: Analogue Electricity Meters.
 

Yes, they would. Eddy currents are induced into the aluminium disc by the current-carrying coils of the meter. The permanent magnet that is part of the meter acts as a brake. Moving the permanent magnet outwards from the centre of the disc reduces the rotation.

Re: Analogue Electricity Meters.
 

Usually a reader rather than a writer but couldn't resist posting on this.

Magnets on the meter was an urban 'myth' which a flat full of skint students set out to prove or disprove half a lifetime ago. First PM speaker magnets, then rare earth mags. borrowed from the lab. Where should they go, what polar orientation, and most importantly what effect?
The result of this experimentation was more heat than light among the resident chemists mathematicians and lawyers. The difference was too negligible to settle a fundamemtal disagreement about whether the 10/- bit lasted longer each night or whether we were missing the shipping forecast as a consequence.

If I recall, there was, however a marginal difference on the load required to start the meter. But not enough to be significant with 6 in residence before the obsolescence of incandescent lamps.

R.

PS - ordinary electric meters are still common here.

Re: Analogue Electricity Meters.
 

How can a magnet "overload" the meter? Would it be saturation in the voltage coil magnetic core causing the voltage coil to take enough current to burn out?

Re: Analogue Electricity Meters.
 

The glass on the meter front prevents the effects of any magnet other than the internal braking permanent magnet, where the disc spins well between the poles.

But it won't've stopped people trying...

Re: Analogue Electricity Meters.
 

It's only a myth because it's actually (by design, probably) very difficult to get enough extra transverse magnetic field through the disc from outside the meter to have much effect on the speed of the disc. It is true that applying a suitable field across the disc will slow it down- that's exactly what the permanent magnets in the meter do so that the disc runs at a speed proportional to the load on the meter output terminals.

Re: Analogue Electricity Meters.
 

I assume the resistance caused by the magnet slowing things down generates enough heat to cause some damage.

I first heard of the magnet trick in an episode of Only Fools & Horses where the Trotter's lack of cash flow led them to stick a magnet on their meter to keep the bill down, but it ended up turning the readings backwards so much the electric board were getting suspicious.

Re: Analogue Electricity Meters.
 

My old friend Mike (still alive, as far as I know) used a big screw driven into the live side feed and a crocodile clip to bypass a pay meter.

Re: Analogue Electricity Meters.
 

What you really needed was a Radiographer to borrow a superconducting magnet off her MRI scanner.;)

Re: Analogue Electricity Meters.
 

Unfortunately, just the refrigeration system needed to keep the magnet superconducting consumes a continuous 7kW or so, plus even a small one weighs a few tonnes.

Two 4" nails and a loop of 16sqmm would be more practical (and probably safer)!

Re: Analogue Electricity Meters.
 

The power consumed by a meter is only 3W or so. Making the disc run slower won't change that or increase the heat input to the disc.

Does anyone have a definitive answer to the overheating possible cause?

Re: Analogue Electricity Meters.
 

I used to assemble these long ago. There are several ways to cheat, none of which I will impart. Magnets may figure but not in the way most folk think.
Main reason for meters overheating is loose connections, and not only where the cables terminate.
Overloading, mainly by using welders, causes vibration which can affect accuracy and shake internal shunt bars loose.

Re: Analogue Electricity Meters.
 

I always wondered whether it was possible to cheat the old card meters by duplicating the magnetic strip on a new card. I figured it should be possible by placing a length of video tape over the strip, heating it with a steam iron and letting the two cool down in contact with one another. Never actually dared try it for real, though .....

The Authorities would have known that the amount of electricity used would be more than the amount of cards I had paid for, and I really didn't fancy the idea of being banned by the electricity board.

Re: Analogue Electricity Meters.
 

Urban myth promulgated by the authorities perhaps?

Re: Analogue Electricity Meters.
 

I believe coaxial meter cables were used in some "problem" areas to thwart this.

Re: Analogue Electricity Meters.
 

Always a possibility.

"Mess with the meter and you may burn your house down" sort of thing.

Probably up there with your chances of being struck by lightning!

Re: Analogue Electricity Meters.
 

If that was a response to my post, I wasn't suggesting there was no danger in messing with your meter and head end. Far from it.

Flash burns. Very nasty.

Prior to the current Smart Meter exercise, customers were offered remote read
current clamp meters that the customer was supposed to install themselves.

Disturbing your meter tails, even with permission, might end badly if something was lose or exposed.

Re: Analogue Electricity Meters.
 

I can remember old electricity meters that would not register at all if the load was VERY small, less than about 10 watts IIRC.
I made a small and crude battery charger that would charge a 12 volt battery at a low enough rate that the consumption did not register.
I could get about half an amp into the battery without the meter registering.

If out all day with nothing else in use, a whole penny could be saved !