Hmm, I think the wikipedia link touched on that; it's just measuring the VA (kWH) of both hot leads. More power makes the meter click faster, basically. The site "How Stuff Works" might have something for you in more detail. I don't pretend to know the cktry inside a meter but it seems to be rather simple. It's not meter design, which I don't seem to be able to find quickly, but it may help too:
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No. IME anyway, the phases are all 120 Vac but each is slightly out of phase (but not 180 degrees) from each other. A 208V ac system is shown here, comprised of the three 120Vac phases:
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As for 220, remember, our systems are different than yours. 240 (here) is "built" from two 120V lines from a center-tapped xfmr, being called 'split phase' since the phase shifting is done via the xfmr on the pole. There are several WYE and DELTA situations which, again, are easy to look up on Google or your favorite search engine. This is an advertisement, but with good information, all based on 220Vac sourced from 120V:
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In industrial buildings, you'll often find humongous wires coming from the xfmr to a quick disconnect and then splitting off to several panels, each panel meant for a separate part of the plant, and within those, heavier panels for the hi-curent equipment. Somewhere in the mix will be large capacitor banks used to correct for power factor and the meters are usually in that same vicinity IME. That's a generality of course, and things vary, but ... that's the gist of it.
I trust that helps a little. It's hard to explain some parts of these things without writing a book that duplicates what's already been written, which is why I use the links for references. You might want to look a tad further into some of the original links I provided you too; occasionally the meat of the info isn't onscreen when you open the page.
An interesting point there - 'large capacitor banks...'
Over here IME most power factor correction is done directly on the equipment so the power factor demand on the incoming supply will stay pretty much the same irrespective of load - which it would probably not in your instance.
UK plugs only recently had plugs mandatory fitted.
- Before then bare wires (perhaps with a bootlace ferrule) were the norm and a person had to wire a plug following instructions on a card pushed over the plug pins.
- Such plugs almost exclusively came supplied with a 13A fuse prefitted until relatively recently.
- Thus many appliances had a power cord which might not be sized correctly for a 13A fuse.
The EU mandated that all appliances be supplied with a pre-fitted plug. This was a way around supplying all appliances with a power cord sized to handle all fault currents which would be unwieldy for small table lamps or standard lamps with long power cords.
Yes some people do know there are 1 3 5 7 10 13A fuses available, however 1A are not for BS1363(/A) plugs - they were for dedicated clock plug/socket (you know, the b@stards with bare brass knurled terminals at the rear fed by bell wire that threw you across the room) and perhaps shaver adapters. However if you DID check the UK I am willing to bet over 90% have a 13A fuse in them - a) that came with the plug b) that was all they had left when the last 3A fuse was used up c) not knowing any different d) not paying =A33 for a pack of 3A or
5A e) assume the MCB will beat the fuse for disconnection of most faults f) can't remember the last time they had to replace a fuse.
A typical BS1362 cartridge fuse will disconnect at 7-10* In (where In is the fuse rating). Thus a 3A fuse will disconnect instantly at
21-30A and a 13A fuse will disconnect instantly at 91-130A. A Type-B circuit breaker will trip
- Before then bare wires (perhaps with a bootlace ferrule) were the norm and a person had to wire a plug following instructions on a card pushed over the plug pins.
- Such plugs almost exclusively came supplied with a 13A fuse prefitted until relatively recently.
- Thus many appliances had a power cord which might not be sized correctly for a 13A fuse.
The EU mandated that all appliances be supplied with a pre-fitted plug. This was a way around supplying all appliances with a power cord sized to handle all fault currents which would be unwieldy for small table lamps or standard lamps with long power cords.
Yes some people do know there are 1 3 5 7 10 13A fuses available, however 1A are not for BS1363(/A) plugs - they were for dedicated clock plug/socket (you know, the b@stards with bare brass knurled terminals at the rear fed by bell wire that threw you across the room) and perhaps shaver adapters. However if you DID check the UK I am willing to bet over 90% have a 13A fuse in them - a) that came with the plug b) that was all they had left when the last 3A fuse was used up c) not knowing any different d) not paying £3 for a pack of 3A or
5A e) assume the MCB will beat the fuse for disconnection of most faults f) can't remember the last time they had to replace a fuse.
A typical BS1362 cartridge fuse will disconnect at 7-10* In (where In is the fuse rating). Thus a 3A fuse will disconnect instantly at
21-30A and a 13A fuse will disconnect instantly at 91-130A. A Type-B circuit breaker will trip
This is the point that I started getting confused, what is so different about a 1 amp BS1362 fuse, as opposed to a 3amp BS1362 fuse (apart from the current rating of course), that I cannot put it into a BS1363 mains plug. They seem to be the same length, and diameter so they should fit, and they have the same voltage rating, maybe something to do with the disconnection time of current ? I remember fitting 1 amp fuses to plugs years ago. Farnell even have them for sale, see
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so what is the problem ?
I really am interested in this and I am not trying to start a Flame war !!!
Same here - all of my soldering irons have 1A fuses; I use 2, 3, 5, 7 10 and [a few] 13A as well. Been doing this for 30 years or more! Have I been lucky with the 1A?
Interesting. The CPC catalogue indicates that they are?
And thank you for those that now agree with me when others said you cannot use 1A BS1362 fuses in BS1363 plugs. I remember using them in the 60's and 70's!!!
That's interesting and makes a LOT of sense! I suppose that could be happening here, but I didn't come across it yet. I've been out of the business for a decade now so lots of things have changed. Who would do the approvals for such a piece of equipment that includes onboard PF correction? I'm familiar enough with a lot of the UK (which I assume "over here" refers to) and even some EU/ET etc. or whatever it's called these days, rules & regs to be able to compare them to our rules & regs. I'm thinking it would have to be the power company themselves, or the grid supplier maybe. Think I'll go look at some large industrial machines sales maybe. You got me real curious!
That's a pretty thorough, consice response; thanks much. A lot of our GFCI's, interestingly enough, will in fact trip if there is a Neutral/Earth fault as in a neutral short to earth ground or a miswire. I discovered this at:
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I wasn't aware of it. I forget the current differential a GFCI trips at, I -think- it's 5 mA, but the link above recommends using 7 mA for testing, which should always open the ckt. This one says 4-5 mA and 1/30 second:
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And if you're intrested at all, here's one that talks about both sides of the pond:
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I've learned a few things today; guess I can relax now!
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