Your assumption that a kettle would boil twice as fast is based on an assum ption that the same size wire and so the same current capacity would be use d. I believe in the UK circuits can be typically 9 or 13 amps, so smaller than the 15 or 20 we typically use.
If we weren't going to save on the cost of wiring there is no real reason t o convert. Boiling water for tea faster is not a very compelling reason to worry with even thinking about which way to go. I suppose hotter room hea ters is another potential advantage, but they are already pretty dangerous now.
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You need two transformers or just two sets of secondaries, one set connected in delta feeding a 6 pulse rectifier and the other set of secondaries connected in wye feeding a separate 6 pulse rectifier. The DC supplies are then connected in series. Thanks to the phase shift between delta and wye, the combined DC ripple is greatly reduced in this 12 pulse configuration.
Using zigzag transformer secondaries, it is easy to make 18 pulse rectifiers.
The nasty thing about a simple 6 pulse rectifier is not so much the ripple but the low power factor, drawing large peak currents. For this reason, some form of power factor correction (PFC) may be needed.
However, if you have to use iron core step-up or step-down transformers, you could easily use a 12 or 18 pulse rectifier, which reduces ripple even further but most importantly increases the power factor, thus nearly sinusoidal current is drawn from the mains.
umption that the same size wire and so the same current capacity would be u sed. I believe in the UK circuits can be typically 9 or 13 amps, so smalle r than the 15 or 20 we typically use.
IDK what they do over there. But yes, I was assuming that we'd continue to use the same size minimum conductors, so a 15A circuit would then deliver twice the power.
to convert.
Who said anything about converting? I said if we were starting from scratch.
Boiling water for tea faster is not a very compelling reason to worry with even thinking about which way to go.
It's not just boiling tea faster. Many older homes have only one 15A circuit for the kitchen counters. Plug in one microwave, you've only got a few hundred watts left. Even in newer homes with two circuits, put a microwave or one of those new convection counter top widgets on it, that circuit is near tapped out. With 240V you could double the power with the same size conductors. I'm just saying that apparently people aren't killing themselves in Europe with 220 volts and it has clear advantages, so it would be logical, IMO, to go with 240V instead of 120V if we were starting from scratch.
On Friday, 1 November 2019 08:32:00 UTC-7, Rick C wrote: ...
umption that the same size wire and so the same current capacity would be u sed. I believe in the UK circuits can be typically 9 or 13 amps, so smalle r than the 15 or 20 we typically use. ...
Strictly speaking the circuits are usually 30Amp (wired as a ring main) wit h a local fuse inside the plug that depends upon the load. It can be up to
ssumption that the same size wire and so the same current capacity would be used. I believe in the UK circuits can be typically 9 or 13 amps, so smal ler than the 15 or 20 we typically use.
on to convert.
Either way. No point if it doesn't save money. That is the point of 3 pha se. While it makes many things more complex, it saves on copper costs.
th even thinking about which way to go.
Now you ARE talking about converting.
Anyone who suggests 240 volts is significantly more dangerous than 120 volt s AC is likely blustering. I haven't found any objective information about it.
I wouldn't have a problem with using 240 volts for common appliances. But the US sockets blow! The UK seems to have some decent ones and integrating a switch is a good idea along with the fuse in the plug. Meanwhile the be st we can do is to add shutters to prevent insertion of small metal probes.
I would support the addition to every outlet of a locking, non-conductive p lug that hangs on a leash so it's always there to be used.
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ssumption that the same size wire and so the same current capacity would be used. I believe in the UK circuits can be typically 9 or 13 amps, so smal ler than the 15 or 20 we typically use.
ith a local fuse inside the plug that depends upon the load. It can be up t o 13A.
So what gauge wire is required in the house? I would think something capab le of handling 30 amps. But that's a matter of how they run the wires real ly and not actually related to the voltage issue.
In the US we run a separate wire to each room or a few rooms (like bedrooms ) with a 15 amp fuse. Kitchens usually have a separate circuit and bathroo ms often have separate circuits because of being on a GFCI breaker. I thin k the UK calls these RCDs.
On 240 volts single phase the amperage could be about 8 with smaller gauge wiring.
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n) with a local fuse inside the plug that depends upon the load. It can be up to 13A.
apable of handling 30 amps. But >that's a matter of how they run the wires really and not actually related to the voltage issue.
is provided by two paths. A 30A fuse or 32A CB protects the circuit.
I've never been a believer in the redundancy thing if you can't verify that the redundancy has not been compromised. once a connection opens up or de velops a high resistance, the two paths are separated and no more redundanc y with no way to detect it. Such redundancy is fine for things that can be properly inspected. For hidden features it would seem to provide a false sense of security.
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One significant advantage is that you easily get a rotating field, so a 3 phase motor is simple, no need for special arrangements to get the motor started. Before VFDs became common, this was an important issue.
One significant problem especially in the US is the low voltages (120/240 V) and hence large currents. This means that the distribution transformer (pole pig) must be very close to the load, which requires a dense medium voltage (14 kV?) network.
The low voltages can be blamed on Edison and his incandesce lamps that initially had a low voltage rating. Later versions could handle voltages over 200 V, so the rest of the world adapted 220-240 V for lamp loads.
Lets speculate what the distribution would look today, if designed from scratch.
Now that the incandesce lamps are gone, a much higher voltage could be selected.
These days a 750 to 1500 Vdc distribution voltage could be selected. If 3 phase is needed for some motors, a VFD from +/-350 Vdc could be used to generate 230/400 V with low distortion. With a DC feed no need for a PFC. For small loads simple DC/DC converters could be used. These would be simpler than current inverters, since there would be no need to generate a sine voltage.
Sorry, I am not reading the whole thread so it may have been said.
The main thing in residential is 110, which is now 125.There are usually on ly a few 220 lines in a US house.
Businesses are another story, they might have three phase. But many now use a delta wye configuration and that provides a 110 line.
Remember even though the might pour fifty tons of steel a day the still hav e an office.
That 75 watts is lees than an amp even at 110, so you don't need a dedicate d circuit or number eight wire or any of that shit.
My considered advice is to go with 110. Even if all you have is 220, in thi s country it is balanced so you can just take of one side and the neutral a nd you got it. In fact you could make a special cord for that real cheap.
Now if you are dealing with three phase that is not delta wye then you need a transformer. I don't know where you are at but it should be cheap in the UK and other 220/240 places. So what you do is get these transformers whic h will be a secondary rated for 240, but you want higher than what it says because it is only 208. It works out to something like 87%. So you choose o ne with a secondary that much higher. And there is no safety issue at all r unning it below its ratings. And none of this shit will be expensive if you only need about an amp.
citors were available for big transmitters. They were large, oil filled wit h ceramic insulators. Some weighed several hundred pounds, but were still i n daily service over 50 years later. Phase correction capacitors used in po wer distribution were similar but usually lower capacitance.
nk a 12 pulse 6-phase rectifier is ~1% ripple
I have never seen that configuration in any transmitter, and I worked on so me that drew over 200KW for the final tubes. Capacitors are cheaper than th e additional components, and they help filter out line transients that extr a diodes don't.
On Nov 1, 2019, snipped-for-privacy@downunder.com wrote (in article):
True.
.
Possibly.
.
Not true.
total cost of a local DC generator feeding a bunch of lighting circuits, where multiple incandescent lamps in parallel were the only load. Electric lights were the killer app for electricity. He was optimizing the whole thing, not just the lamps. The economic optimum was broad, centered around
100 volts.
I have not seen the analyses from Europe when they settled on 220 V (versus
wiring plant weighed more heavily in their calculations. Small electric motors may have also entered into the analysis. Also, retrofitting power wires in existing masonry and stuccoed structures is easier if the wires are small and flexible, suited to being grouted into grooves chiseled into solid masonry walls.
War story: I lived in Sweden in the mid 1970s, designing circuitry for a small company. Prototyping (vector board, tinned solid wire, axial-leaded components) involved a lot of hand soldering, and the smoke gave me raging headaches, so I asked my business partner if he had a fan with speed control that I could use to blow the smoke away. He said yes, and disappeared into the sub-basement of the large apartment block in Stockholm where we were located, and came back with this beautiful old enameled iron and brass desk fan, which a built-in rheostat speed control It had not been used in decades, so I cleaned and oiled it, and then tested it. It just hummed a bit and the blades moved slowly. Hmm. Then it hit me - why was this beautiful fan in the dusty sub-basement? And the iron was not laminated. Looked at its nameplate - Gleichstrom! It was made in the days when utility power was DC, but it was too well made (and expensive) to be thrown away. Sweden converted to AC power circa 1920, so that beautiful fan had lain in storage for almost sixty years. Anyway, the march of technology saved the day. I made a four-diode full wave rectifier bridge from some 1N4005 diodes and heat-shrink tubing, and installed the bridge in the fan base. Bingo! I used that fan from then on.
Epilog: In 2017, I visited my now retired business partner (now in his mid eighties). He still has that fan, and it still works perfectly. Must be at least a century old by now.
assumption that the same size wire and so the same current capacity would be used. I believe in the UK circuits can be typically 9 or 13 amps, so sm aller than the 15 or 20 we typically use.
ason to convert.
hase. While it makes many things more complex, it saves on copper costs.
with even thinking about which way to go.
Geez, you want to argue about everything. First you claim I was talking about converting. I clearly said I was not. Now you're claiming I'm taking about it again. Nothing in the above says anything about converting. Modern kitchen appliances use more power, eg microwaves and kitchens have more of them. If we used
240V, it makes it easier and less expensive to deliver that power. Nothing there about converting what is already there, it's beyond ridiculous to even be thinking about that.
lts AC is likely blustering. I haven't found any objective information abo ut it.
t the US sockets blow! The UK seems to have some decent ones and integrati ng a switch is a good idea along with the fuse in the plug. Meanwhile the best we can do is to add shutters to prevent insertion of small metal probe s.
plug that hangs on a leash so it's always there to be used.
You want them, you buy them and install them. Leave me and my receptacles alone.
On Friday, November 1, 2019 at 2:52:04 PM UTC-4, snipped-for-privacy@downunder.com wro te:
n assumption that the same size wire and so the same current capacity would be used. I believe in the UK circuits can be typically 9 or 13 amps, so s maller than the 15 or 20 we typically use.
eason to convert.
phase. While it makes many things more complex, it saves on copper costs.
You're advocating 750 to 1500 volts going into homes, small businesses, etc?
ssumption that the same size wire and so the same current capacity would be used. I believe in the UK circuits can be typically 9 or 13 amps, so smal ler than the 15 or 20 we typically use.
ith a local fuse inside the plug that depends upon the load. It can be up t o 13A.
So, instead of conductors being smaller than what is typically used in the US where we have 15a or 20a, the conductors are actually larger. Higher voltage and higher current. Thanks for clearing that up.
No, we have soclialism to build. Currently the price of 1MWh is 168PLN on the wholesale market, 500-600 PLN for end users. The difference is made of multiple taxes and other "quality fees".
It's actually 120/240 and has been for more than half a century in the USA, at least in any places that matter.
Delta wye? There is delta and there is wye. Wye give you 120 volts as one option. Delta would give you 208. But again, if he's talking about some mass market widget, the largest market for a 75W plug-in widget is 120V.
Much of the electric hardware is certified for the whole Low Voltage Directive (LVD, max 1000 Vac, 1500 Vdc) range. The wiring practices would not need radical changes.
The problem would be some of the Far-East import, which is not compatible even wish 230 Vac (creepage distances etc. :-)
The idea behind the old UK ring mains system is that a single feed is zigzagging through all rooms and this will reduce the amount of cables required compared to individual cabling from the distribution point with individual cables to each room as used in most countries.
Due to the long zigzagging cable, the voltage loss would be large in the far end. To reduce the losses, the far end of the cable is returned back to the feed point.
Of course there must be fuses at both ends of the ring. Even if one fuse is blown, current would be flowing from the opposite end with larger voltage drops. Of course, if the short is still persisting, it will also blow the other fuse.
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