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In an old building with widely spaced conductors, the three phase wiring was a big emf generator which caused problems. The wiring was in ventilated conduits probably about 8 by 6 inches. Ran right through some occupied rooms.
Greg
Two of three wires but only one of three phases.
Dear Androcles,
With any two phases of a 3 phase (or more) system and suitable transformers, I can generate the other phases. For example, if I have 2 phases of a 3 phase Y system (separated by 120 degrees) and a Y-Delta transformer bank, I can connect the two phases and neutral to two of the Y connections and the neutral point of the transformer bank and the 3 phase load to either the Y side or the delta side, as appropiate, and the transformer bank will supply the missing phase.
Please give me a schematic to generate 3 phases from my 2 phase (as you claim) 120V/240V Edison system in my house. Since you say I have 2 of the 3 phases, it must be possible.
I have a source of inexpensive machine tools I'd like to get, they are, however, all three phase equipment.
| >> >| > | > Usually there are two wires a plus (+) and a minus (-). | | >> >| > | | >> >| > | In the U.S., one swings between + and - (the "hot" wire), | and the | >> >| > other sits at zero voltage (the "common" wire). That is | because | >> >| > residential two-phase wiring here is AC, and therefore | there is no | >> >| > positive wire nor negative wire. I expect that the | same holds in the | >> >| > Netherlands. | >> >| >
| >> >| > Nope. | >> >| > Europe uses 415V 3-phase and neutral 50 Hz. Domestic is single phase and | >> >| > neutral, 230V. There is no 110V 60 Hz here. | >> >| | >> >| Which is the same as US residential distribution, except for the voltage | >> >| and frequency. | >> >| | >> >Not quite. | >> >In Europe each home gets one phase and grounded neutral from a large | >> >communal transformer, but in the US each home gets two phases and | >> >neutral from a smaller individual transformer and the two phases are not | >> >clearly identified by a colour code as they are in Europe. | >>
| >> In USA, homes generally get one phase of the 3 phases, not two. | >>
| >> Two 120V legs 180 degrees out of phase with each other comprise one | >> phase, not two. Two phases out of 3 are 120 degrees apart, not 180. | >>
| >> Just for giggles, there is such a thing (not common) as "2-phase". The | >> two phases there are 90 degrees apart. 2-phase and 3-phase can be | >> converted back and forth between each other with transformer arrangements. | >> -- | >> - Don Klipstein ( snipped-for-privacy@misty.com) | >
| >208 volts is frequently used within large complexes. Two of three | >phase. | >
| >Greg | | Two of three wires but only one of three phases. | You really should learn to count.
According to code in Canada , either a 2 pole breaker or two breakers which have their trip levers "ganged" are required. Panel layout facilitates this. Don Kelly cross out to reply
Begone troll. Hey, I actually ran into a Scott-T transformer configuration recently in a fairly large vacuum furnace. It does some 'interesting' things when not loaded in a balanced manner.
Best regards, Spehro Pefhany
-- "it's the network..." "The Journey is the reward" speff@interlog.com Info for manufacturers: http://www.trexon.com Embedded software/hardware/analog Info for designers: http://www.speff.com
On Wed, 18 May 2011 10:12:16 +0100, Androcles rearranged some electrons to say:
I'm glad that you finally admitted that you were wrong all along.
Have a shitty day!
Yeah, that's what I figured. Seems to me that much confusion is created when imprecise language is used. If Edison's DC had used V, ground, and -V it would still be DC, but a different DC to 2V, V and ground. Who puts a centre tap on a car battery and grounds it? What's the advantage of split phase when you need double pole instead of single pole switches to control it?
In the US, older installations will have two fuses, which cannot be ganged. Actually they are in a cartridge which removes both fuses at once so removing power (by removing the cartridge) removes all the power, but only one fuse blows at a time. Often symptoms in a dryer is the motor will run (it's 120V, one line to neutral) but the element won't heat (line to line with blown fuse).
Anything with circuit breakers will have ganged breakers.
1) Only 120V to anything grounded, safer. (Britian does/did something similar for construction equipment, 120V CT, center tap grounded. Safer in wet locations, only 60V to ground 120V items connected end to end) 2) Naturally balances toward low neutral current, while one end grounded would be completely unbalanced (all 120V circuits would be from the center tap to the grounded end tap, you wouldn't want to connect anything from 240V to 120V). Makes for less voltage drop to the house. One end grounded has max current on its neutral, the sum of everything.
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HEY CUT IT OUT! I KINDA LIKE ANDIE. HE'S NOT STUCK UP LIKE SOME OF YOU CHAP-PERRONES. TGITM
Pattycakes, it's considered extremely low form to alter other's writing and then "quote" them as if they were actually made.
As I said, this discussion is no place for retards playing ghost. Why don't you run along? Roy needs some good lovin'.
BTW why do you always misspell your name? You know it's "Pattycakes".
"Androcles" wrote in message news:qhZAp.639$ snipped-for-privacy@newsfe24.ams...
| Ok, I see what you are saying. You don't connect the delta because | you connect the centre taps, whereas I was reading it as connecting | the delta and not connecting the centre taps. I'm still uncomfortable | with two unidentified hot wires and one cold being called single | phase, even if it is, technically. I knew of a clothes dryer I was asked | to look at (I didn't really want the job) and I put an ohmmeter on it. | One phase was open circuit, the other was resistive to ground. | That made no sense to me, so I told her to call a technician. | It turned out that a Kirby grip had found its way into the heating | element and welded itself to one side and ground, the other side | having parted company. Had it been open circuit neutral I would | have diagnosed it, although I had no replacement element so it really | didn't matter. In my mind if one line was open they should both be, | I couldn't imagine a breaker that only opened one line when two | were hot. Oh well, can't win 'em all. | | According to code in Canada , either a 2 pole breaker or two breakers which | have their trip levers "ganged" are required. Panel layout facilitates this.
Yeah, that's what I figured. Seems to me that much confusion is created when imprecise language is used. If Edison's DC had used V, ground, and -V it would still be DC, but a different DC to 2V, V and ground. Who puts a centre tap on a car battery and grounds it? What's the advantage of split phase when you need double pole instead of single pole switches to control it?
---------------------------------- The advantage occurs when most of the load is 120V. This load is split so that half the 120V circuits are from A to N and the others from B to N Each circuit requires only a 1 pole breaker. A--------N---------B Heavier loads such as the dryer or an oven are connected A to B for 240V service.(The dryer element may have two heat settings (full element at 240V and half at 120V (using a centre tap) A two pole breaker is then needed. In my house, I have 1-2pole 30A 240A breaker for the dryer, 1-2pole 40A
240V breaker for a stove (not in use as my present stove is gas) and 18 single pole breakers 15A breakers for 120V circuits. 3 of these are ganged as 2 pole because kitchen duplex outlets must have the two outlets on different circuits to eliminate the nuisance involved in running a 1200W toaster and a 1500Watt kettle on the same circuit at the same time. The panel has room for more breakers, if needed and has a 2 pole 200A main breaker.Don Kelly cross out to reply
WHAT A LOAD OF MINDLESS USELESS TROLL DROOL. TGITM
The kettle alone is 3 kW.
One socket was on a spur going outside for the electric lawn mower. Ten sockets were for her computer and peripherals. Another ring main for the living room and utility room and another for all the upstairs bedrooms. The shower is on a separate circuit, that's 10 kW and the IEEE regulations for bathrooms is strict.
Everything you've said looks like a disadvantage to me, I asked what the advantage was. :-)
The kettle alone is 3 kW.
One socket was on a spur going outside for the electric lawn mower. Ten sockets were for her computer and peripherals. Another ring main for the living room and utility room and another for all the upstairs bedrooms. The shower is on a separate circuit, that's 10 kW and the IEEE regulations for bathrooms is strict.
Everything you've said looks like a disadvantage to me, I asked what the advantage was. :-)
------------------------------ You can't wire for a balanced load so the best you can do is put half the
15A circuits on one leg and half on the other leg (phase to you). Each of these circuits will need 2 wires, live and neutral although in recent years the code requires a 3rd "ground" wire of smaller gauge which does not normally carry current. Panel construction interleaves the legs so that 2 adjacent breakers are on different legs so there is really no big choice to be made by the electrician (it also facilitates the use of 2 pole breakers). This is similar to UK usage except that the ground and neutral are tied together at the main panel (and to ground there). Only in the case of kitchen duplex outlets will there be 2 hot wires- other duplex outlets have only one hot wire. 120V appliances are limited to 15A- vs 7.5A for the corresponding 240V appliance. Certainly a UK kettle at 3KW will heat up a lot faster than a US kettle at 1.5KW so there is a disadvantage. However the appliances requiring 3KW will be designed for and fed 240V and typically will be on a dedicated circuit so it isn't a big deal. Definitely not a cause for disaster.The ring main approach requires fused appliance outlets. The North American system is radial- each 15A circuit may have several outlets on the same circuit- the disadvantage is that if the breaker is tripped, all the outlets on that circuit are dead. On the other hand, wiring and outlets are simpler- no fuses on outlets and generally no switches on them. I have an outside circuit on on a GFI breaker and any outlets in bathrooms are also on GFI
Why the UK went one way and North America another way is something that is conjecture. Possibly the Edison DC system set the direction in North America. The problem is that once a region goes down a given path, it is very difficult to make a radical change (and it would be radical). Safety-no big advantage one way or the other- as an old prof of mine (from the UK) said 'you can make something fool proof but you can't make it damn-fool proof".
Yes there are advantages to the UK system but there are cost advantages to the American system- on average less copper and simpler outlets and plugs. The trade off is often in the mind of the user -what he is used to dealing with is best.
Don Kelly cross out to reply
Our domestic circuits are 30 amp, 230 V RMS. 15 amps just doesn't cut it. Balancing is left to the supply company by distributing 3 phase and neutral among different houses. Since the primary side the transformer has the same balance problem on both sides of the Atlantic, what is the advantage of centre taps and an addition wire on the secondary side?
| The ring main approach requires fused appliance outlets. The North American | system is radial- each 15A circuit may have several outlets on the same | circuit- the disadvantage is that if the breaker is tripped, all the outlets | on that circuit are dead. On the other hand, wiring and outlets are | simpler- no fuses on outlets and generally no switches on them.
I don't agree that double pole switches are simpler than single pole. I certainly don't agree that two fuses in one circuit is simpler. Blow one and the potential is still present from the other. Along comes the electrician looking for a fault, sticks his neon screwdriver on the "return" wire and finds it is live through the appliance, even though the fuse carrier has been removed.
| I have an outside circuit on on a GFI breaker and any outlets in bathrooms | are also on GFI | | Why the UK went one way and North America another way is something that is | conjecture. Possibly the Edison DC system set the direction in North | America. | The problem is that once a region goes down a given path, it is very | difficult to make a radical change (and it would be radical).
Yep. That's the real issue; once a standard, always a standard. We are stuck with our big square plugs, even though my phone charger has a plastic ground pin and a USB cable that can also charge the phone from the 5V DC of my computer.
| Safety-no big advantage one way or the other- as an old prof of mine (from | the UK) said 'you can make something fool proof but you can't make it | damn-fool proof". | | Yes there are advantages to the UK system but there are cost advantages to | the American system- on average less copper and simpler outlets and plugs.
Surely you mean MORE copper on average? You need to carry twice the current at half the voltage for the same power. That's twice as much copper per house.
| The trade off is often in the mind of the user -what he is used to dealing | with is best. | That too. I'm more inclined toward Americans being paranoid about electricity, scared by Edison building an electric chair for execution. Hence 110V.
The nation has been at 120 Volts for more than half a century, idiot.
240 Volt, center tapped secondaries feed homes here.Since you appear thick on math or history or both, half that is 120 Volts.
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PANDORCULOS, YOU HAVE TO STOP RESPONDING TO DONKEY KONG. TGITM
While I do not quite understand the point of having a ring mains, having a fuse in each plug with the amperage ratings set according to the load makes sense. In this case, the extension wire loop resistance is only required to blow this plug fuse (2-13 A).
In a normal radial 230 V system with 10 or 16 A fuses in each leg, the total loop resistance including the longest fixed wire part plus any long extension cord(s) feeding he load, must be so low that in a short/ground fault, the current must be so large (50-100 A) that it will blow the fuse in a very short time (less than a second). Thus the total loop resistance (live+neutral/protective ground) must be in the order of 1-2 ohms
For this reason, the grounded extension cords of any significant length, must have at least 1.5 mm2 conductors, even if the nominal load for the device would be less than 1 A.
| >
In the diagram there are six pairs of outlets for a total of 12. Imagine this were two spurs, 6 on each spur. The maximum current on each spur is 15 amps so the breaker to protect it is a 15 amp breaker or fuse. Now the whole point of having socket outlets is that you can connect and disconnect different appliances. You plug in the food mixer, mix the food, unplug it and put away again. But suppose one spur is already carrying 12 amps for the dishwasher and the food mixer needs 5. You pop the breaker at
17 amps. Reset it and plug the mixer on the other spur, a different socket. But by closing the ring (i.e. connecting the ends of the spur together) your current carrying capacity is 15 amps in BOTH spurs, so you can protect it with a 30 amp breaker and plug your food mixer in any socket without popping the breaker. A ring main doubles the current carrying capacity of every socket.| having a fuse in each plug with the amperage ratings set according to | the load makes sense. In this case, the extension wire loop resistance | is only required to blow this plug fuse (2-13 A). | | In a normal radial 230 V system with 10 or 16 A fuses in each leg, the | total loop resistance including the longest fixed wire part plus any | long extension cord(s) feeding he load, must be so low that in a | short/ground fault, the current must be so large (50-100 A) that it | will blow the fuse in a very short time (less than a second). Thus the | total loop resistance (live+neutral/protective ground) must be in the | order of 1-2 ohms | | For this reason, the grounded extension cords of any significant | length, must have at least 1.5 mm2 conductors, even if the nominal | load for the device would be less than 1 A. |
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