Check the actual papers.[1][2] For single-phase meters, which covers most residential uses, this is a non-problem: "No deviation beyond the specification could be observed; no influence of interference due to interfering or distorted voltage, and no influence caused by interfering currents were observed." All the problems were seen with 3-phase meters, usually found only in industrial and commercial environments.
Figure 3 of [1] is puzzling. They claim to be testing a 3-phase meter, but the circuit shown is single-phase. Are they testing 3-phase meters with only one phase connected? That's way out of balance; 3-phase systems normally have at least roughly equal loads on each phase. While a 3-phase meter with an wildly asymmetrical load ought to measure accurately, that's not a normal condition.
In most parts of Europe 3-phase is the standard. Neither high-leg delta nor split phase have significant deployment outside North America.
That being said, in household use the per-household balancing between the phases is usually very poor (e.g. all lightning on one phase). Overall the balancing turns out ok across the grid, but the meter doesn't see that. So this is a very relevant condition for household meters.
Ah. That's helpful. US utility residential practice, for those outside the US, is that pole transformers take in 3 phase at a few KV, at 60Hz, and output 120/240 VAC single phase with a shared neutral. That's what most houses get, supplied over 3 wires, with a 3-wire single phase meter.
Pole-mounted transformers usually serve about 7 houses or so.
Even in apartment buildings, each apartment has its own meter, almost always single phase.
I'm interested in what area the overhead lines are only 1.1 kV. From what I have seen the high-side voltages are much higher, in the range of 7 kV or 14.4 kV line to ground.
Also, most overhead transformers I have seen are entirely single phase. Often you will see a bank of 3 single-phase transformers if a customer requires 3 phase service. Larger customers are connected to a pad-mounted 3-phase transformer connected to the primary overhead service through an underground dip from the pole.
Yeah, you are right. I think what they were trying to say is that the transformers are fed on the high side by one of three phases (as is typical), and that the residential step-down is a split phase 120/240.
Yes - we had a power cut recently and when I went outside you could see it was affecting every third house, i.e. just a single phase had gone. Reported it and it was fixed promptly.
Most new apartment buildings in Poland have 3 phases connected to all apartments. Since there's municipal central heating, there's no point in connecting natural gas to those buildings, so you're forced to use induction stovetops. And those are much more efficient with 3 phases.
I'm no electrician but I'm sure 3-phase meters are a norm in Estonia. You would usually have devices with high power requirement like electric water heaters and ovens connected to separate phases. And they are often sitting idle as well.
In the US, devices with high power requirements are generally connected "between" phases -- the phase-to-neutral voltage is(depending on your transformer configuration) generally 120v, with some configurations generating 208v from 1 of the 3 phases to neutral. Phase-to-phase voltage is generally 220-240v.
Loads that span all 3 phases are generally motor loads that will benefit from the rotating magnetic field that 3-phase service provides -- such as pumps and compressors.
Three phase power has three hot conductors, 120 degrees out of phase to each other. In the US it can be delivered at a bunch of different voltages, depending on what transformer the customer installs, but generally I worked with 277/480. (277V hot to neutral, 480V hot to hot. Generally all commercial lighting runs on 277V.)
And to be specific, three phase is primarily useful because motors that use it are self-starting, you don't need to capacitor-and-switch arrangement single phase motors use, which frequently break. Less important now that most big motors use VFDs. Also, supposedly due to some frequency voodoo you don't need to use as much cable when running three phrase transmission cable.
Thanks for the clarification and much more detailed explanation. I was aware of the split-phase nuance and have been hit by 277 a couple of not-so-fun times.
As to the benefit to motors, it was my understanding that using split-phase or a single phase and a capacitor creates a less-than-optimal magnetic field which results in more noise/vibration and wear on the motor as opposed to 3 phase.
There also exists 120/208 three phase in the US. 120V phase to neutral, 208V phase to phase. It's very common in commercial buildings that don't have big loads.
Norway is a different case from most of the rest of the world, we run what's called an IT network earthing system where there is no neutral lead. Everything is connected between two phases getting 240v, and the earth wire is tapped from an actual metal rod dug into the earth.
This setup is pretty much a mess, and can wreak havoc on laboratory setups, so e.g. at universities all the lab rooms are laid out with TN (the standard everyone else uses). This means you can mess stuff up in the lab by running an extension cord from the adjacent non-lab room (e.g. get large ground voltage differences, all sorts of wanky stuff).
I'm in EU too. We had recently a blown fuse or something in the entire 5 story building, the result was sort of weird: lights were ok in the entire house, half of the power sockets in the flat were ok, half of the power sockets were without power. That's when I realized that each of these 230V circuits are probably connected to a different phase. (Perhaps so that the load gets distributed evenly)
All the places I've lived in (UK) used a 32A 240V radial spur with a dedicated breaker with the appliance hardwired, or a regular wall socket on the kitchen ring main, 13A 240V, with a shared breaker (lower power portable appliance). Never seen 2-phase wiring for domestic use.
I thought, but I could be wrong, that UK cookers use a radial spur with a dedicated breaker, and that sometimes those breakers also include a standard regular wall socket, but this socket (and the cooker) are still on their own radial spur.
The cooker should never be connected to a normal kitchen ring main.
> Q1.18 Appendix 15 of BS 7671: 2008 gives advice on ring final circuits and sharing/spreading the load around the circuit. Item (iii) suggests that cookers, ovens and hobs over 2 kW should be on their own dedicated circuit. Why can’t ovens of less than 3 kW be connected to a ring final circuit via a suitable connection point such as a socket-outlet or fused connection unit?
> Appendix 15 is intended to give guidance only. Such connection is not prohibited, provided that no part of the ring final circuit will be overloaded as a result.
> Regulation number(s)
> 433.1.5
So, not forbidden, but if you have new wiring the electrician is going to give the cooker its own circuit.
Just checked in my new-ish flat where I have an electric oven only (gas hob). It's a 13A square pin standard wall socket, but does have a dedicated breaker, so it is indeed not on the ring main for the other wall sockets. It has a 32A MCB in the consumer unit (same as on the two main rings). Not sure if it's ring or radial without removing the socket.
One phase is the standard in UK and Spain too. You don't get the same amount of Watts outs of a hob wired with one phase, and most hobs seem to be possible to wire either way.
I'm trying to google a diagram, but I only find a bunch of forum posts that explain. For Neff stuff (the one we have), the connectors are numbered 1, 2, 3, 4 and 5.
1-2-3 would be separate phases in a 3-phase home and joined together for a single phase.
I know nothing about spain but the UK is the exception to all rules, particularly electricity wise. It evennused to have its own color coding and circuit design.
> Most European transformers are three-phase and on the order of 300 to 1000 kVA, much larger than typical North American 25- or 50-kVA single-phase units.
Electric stoves in Germany are usually hooked up to a special 3 phase wire in the kitchen, but thats the only exception in can think of, at least for apartments.
bjelkeman-again is referring to kVA- a unit of power rather than voltage.
Systems which run a higher consumer voltage (e.g. 230V) will tend to use higher kVA transformers compared to the American system (~110V).
I believe this is because it is feasible to run longer cables when using higher voltage (higher voltage -> lower current -> lower thermal losses per metre of cable), hence it is economical to use fewer, larger transformers in a higher voltage system vs. a lower voltage system.
Figure 3 of [1] is puzzling. They claim to be testing a 3-phase meter, but the circuit shown is single-phase. Are they testing 3-phase meters with only one phase connected? That's way out of balance; 3-phase systems normally have at least roughly equal loads on each phase. While a 3-phase meter with an wildly asymmetrical load ought to measure accurately, that's not a normal condition.
[1] http://doc.utwente.nl/102016/1/Runaway_energy_Meters.pdf [2] http://ieeexplore.ieee.org/document/7866234/