120 V or 240 V Mains - which voltage is better?

[psionl0]

In the US system, the same wires are used in the 120V and 240V parts of the system.

Are they literally the same set of wires (ie on the same fuse) as the 120V outlets or do the 240V parts of the system run on a different set of wires that have their own fuse at the meter box?

 

[Macgyver1968]

It's different .. voltage and current are 2 sides of the same coin (well, together with resistance) you can't have one without another. Gunpowder and bullet are just two things.

120V is safer for sure, but it's by no means 100% safe.

I realize it's not a perfect analogy, but the point I was trying to make is the way that phrase is worded, it might make someone who is unfamiliar with the nature of electricity think that voltage isn't dangerous...when in fact it is.

"hey look!! it says 'caution, high voltage' but you know the old saying...volts don't kill, so BZZZZZZZZZZ(crackle)BZZZZZZZZZZZ(crackle, crackle) (thud)(smoke)

 

[aleCcowaN]

PS: People who don't know what phase means in power provision shouldn't speak of it.

3 live to neutral voltages each 120 degrees out of phase relative to each other is 3 phase power.

But 2 live to neutral voltages both 180 degrees out of phase relative to each other is NOT 2 phase power. Got it.

LOL

Paraphrasing you: "three different people looking to each other are three people, but one person looking at himself in the mirror is NOT twins. Got it. "

Yes, I know you can't understand, but believe me psionl0, it's not twins.

That's what the group of "People who don't know what phase means in power provision shouldn't speak of it." was meant to do (basically with you in mind).

 

[Dabop]

Yes, I get that Oz is wired differently than the States,

Actually I would put it as 'the States wire differently to most of the rest of the world.....'

being the more accurate way of stating (hehe) it

irregardless, it is NOT the higher voltage 'requires' the larger cables used, but the way you lot use it for larger loads....

the fact remains that higher voltages do NOT need bigger wires, and in fact by doubling the voltage to 240vac, you actually halve the current needed compared to if you had stayed at the lower 110v for the same sized load....

 

[psionl0]

LOL

Paraphrasing you: "three different people looking to each other are three people, but one person looking at himself in the mirror is NOT twins. Got it. "

Yes, I know you can't understand, but believe me psionl0, it's not twins.

That's what the group of "People who don't know what phase means in power provision shouldn't speak of it." was meant to do (basically with you in mind).

Now you are trying to say this is a imaginary thing and not just a dictionary thing.

You can claim that the primary side of the transformer is supplied by single phase power but that doesn't mean that the split secondary side is not two phase power (unless you want to give it a different name).

ETA as far as the house is concerned, there is no difference between being supplied by a split secondary of a transformer and being supplied by two separate generators each exactly 180 degrees apart so this is not just "looking in the mirror".

 

[Dabop]

I realize it's not a perfect analogy, but the point I was trying to make is the way that phrase is worded, it might make someone who is unfamiliar with the nature of electricity think that voltage isn't dangerous...when in fact it is.

"hey look!! it says 'caution, high voltage' but you know the old saying...volts don't kill, so BZZZZZZZZZZ(crackle)BZZZZZZZZZZZ(crackle, crackle) (thud)(smoke)

You will find this amusing then- our 240vac single phase actually have 'danger- low voltage' warning signs on them, as 240v is classified under AS as being low voltage (under 60v is ELV or extra low voltage)

 

[aleCcowaN]

"hey look!! it says 'caution, high voltage' but you know the old saying...volts don't kill, so BZZZZZZZZZZ(crackle)BZZZZZZZZZZZ(crackle, crackle) (thud)(smoke)

Who told you to be so conductive?



--------------------------------------------------------

The current capable of interfere with nervous signals is 1mA. That's why, as human being are electrolytic conductors with an electric resistance of about 200 to 500 KiloOhms from one hand to another, it's almost as difficult to get electrocuted with 240V than with 110V. Difficult, but not impossible, and when it happens it's not quick.

 

[Dabop]

Scarily, when I first started my apprenticeship as an electrical fitter, multimeters were very uncommon (and VERY expensive), we had exactly ONE in the entire department (an AVO8)
We had 'test lights' but being incandescent bulbs, usually were lying in brokn pieces at the bottom of your toolbox...

DO NOT DO THIS!!!!

The way the oldtimers tested for live wires was to lick the back of their hand and then touch the BACK of their hand to the terminal to be tested...- keeping your head out of the way!!!

If it was live- your muscles would contract and your arm would violently swing away from the terminal (hence keeping your head out the road- I actually saw a guy punch himself in the face doing this!)

REPEAT DO NOT DO THIS!!!!

 

[aleCcowaN]

Now you are trying to say this is a imaginary thing and not just a dictionary thing.

You can claim that the primary side of the transformer is supplied by single phase power but that doesn't mean that the split secondary side is not two phase power (unless you want to give it a different name).

ETA as far as the house is concerned, there is no difference between being supplied by a split secondary of a transformer and being supplied by two separate generators each exactly 180 degrees apart so this is not just "looking in the mirror".

Good try!!! But yet wrong. There's no difference between twins and a person plus his image reflected in two mirrors, yet twins could do different things that a person and his reflection cannot.

You're ignorance in this matter is overwhelming. It won't matter to you that the system is called split-phase and not two-phase (because there are not two phases in it and there never will other but one single phase who is split into two lines) and that anyone with a minimal education and common sense can spot it. As usual, you will continue your spree of nonsense just out of pride, without realizing your fantasy of a two-phase system cannot construct other than the original only-phase with higher tension, while a real two-phase system with 120° spread allows to reconstruct a three-phase system with constant instant power, as much as a full three-phase system allows to generate any number of multiphase systems.

Foreseeing foolish retorts like yours is why I said above "an autotransformer is neither a two-or-more phase system". You don't have the slightest notion on how and why polyphase electricity exists yet who could keep you quiet.

 

[psionl0]

Foreseeing foolish retorts like yours is why I said above "an autotransformer is neither a two-or-more phase system". You don't have the slightest notion on how and why polyphase electricity exists yet who could keep you quiet.

You might be a legend in your own mind but you have no idea what I know about multi-phase electricity. Your attempted red herring about "two-phase system with 120° spread" is just a massive fail.

Why don't you address what I actually posted instead of attacking the arguer?

 

[Modified]

Good try!!! But yet wrong. There's no difference between twins and a person plus his image reflected in two mirrors, yet twins could do different things that a person and his reflection cannot.

You're ignorance in this matter is overwhelming. It won't matter to you that the system is called split-phase and not two-phase (because there are not two phases in it and there never will other but one single phase who is split into two lines) and that anyone with a minimal education and common sense can spot it. As usual, you will continue your spree of nonsense just out of pride, without realizing your fantasy of a two-phase system cannot construct other than the original only-phase with higher tension, while a real two-phase system with 120° spread allows to reconstruct a three-phase system with constant instant power, as much as a full three-phase system allows to generate any number of multiphase systems.

Foreseeing foolish retorts like yours is why I said above "an autotransformer is neither a two-or-more phase system". You don't have the slightest notion on how and why polyphase electricity exists yet who could keep you quiet.

Semantics.

 

[Dabop]

Good try!!! But yet wrong. There's no difference between twins and a person plus his image reflected in two mirrors, yet twins could do different things that a person and his reflection cannot.

You're ignorance in this matter is overwhelming. It won't matter to you that the system is called split-phase and not two-phase (because there are not two phases in it and there never will other but one single phase who is split into two lines) and that anyone with a minimal education and common sense can spot it. As usual, you will continue your spree of nonsense just out of pride, without realizing your fantasy of a two-phase system cannot construct other than the original only-phase with higher tension, while a real two-phase system with 120° spread allows to reconstruct a three-phase system with constant instant power, as much as a full three-phase system allows to generate any number of multiphase systems.

Foreseeing foolish retorts like yours is why I said above "an autotransformer is neither a two-or-more phase system". You don't have the slightest notion on how and why polyphase electricity exists yet who could keep you quiet.

edit again lost the original post in editing...
180 deg 2 phase systems were (are still are in remote rural areas) called 2 phases here in Oz

edit to add

http://www.aussiefrogs.com/forum/te...ats-difference-between-1-2-3-phase-power.html

this explains the various rural supplies and the various ways they could be configured as found in Oz
edit again again- there it is....


Hate to disagree again (esp in the one thread) but 180 deg phases in oz were indeed called 2 phase power....

 

[psionl0]

Semantics.

Essentially but aleC was trying to justify it (and show how clever he is) by pointing out that unlike the case with 3 phase power, you can't add voltages that are in phase or anti-phase in any proportions and produce a third voltage with a different phase angle. Unfortunately, he gave himself away when he called the transformer that supplies power to the house an "autotransformer".

 

[Dabop]

I suspect he is trying to shoehorn theory into a practical discussion lol

As far as it went here- it could come from a 2,3 or twenty phase supply- didnt care as long as that single phase was 240v that you could plug your tv or whatever into

(in some industrial configurations, they had weird and very dangerous to work on 6 phase installations that had to be very carefully worked on - basically 2 independent 3 phase 415 volt systems that could be if incorrectly wired, capable of melting /arcing through the standard insulation on the cables if laid side by side in the same wiring tray)

 

[jsfisher]

Are they literally the same set of wires (ie on the same fuse) as the 120V outlets or do the 240V parts of the system run on a different set of wires that have their own fuse at the meter box?

The 120V circuits are wired completely separate from the 240V ones. Most 120V circuits are for outlets and lighting, so a single 120V circuit may provide service to multiple outlets and/or lights.

 

[psionl0]

As far as it went here- it could come from a 2,3 or twenty phase supply- didnt care as long as that single phase was 240v that you could plug your tv or whatever into

And that is probably the case with the typical American household too (apart from their 240V ovens etc).

However, 3 phase electricity has the unique advantage that the total instantaneous power consumed by a 3 phase appliance is constant (instead of cycling at twice the mains frequency). You can imagine how that would save on armature stress on a heavy duty motor.

This is mainly an industrial issue but 3 phase motors (and similar appliances) also have advantages in some households as well. That is why I wondered about US households that wanted a genuine 3 phase power in the OP (no problem for the rest of the world of course).

 

[aleCcowaN]

You might be a legend in your own mind but you have no idea what I know about multi-phase electricity. Your attempted red herring about "two-phase system with 120° spread" is just a massive fail.

Why don't you address what I actually posted instead of attacking the arguer?

Essentially but aleC was trying to justify it (and show how clever he is) by pointing out that unlike the case with 3 phase power, you can't add voltages that are in phase or anti-phase in any proportions and produce a third voltage with a different phase angle. Unfortunately, he gave himself away when he called the transformer that supplies power to the house an "autotransformer".

Load of tosh in red. Try at least to seed some notion that can't be proved false just by reading what is already posted here. The "he said what I want him to have said" doesn't work in written media, though you'll try it just because someone may leave the debate.

Unlike some other words, there's no "semantics" here but essentials. How folks call any system in Oz is just folklore. The link provided by Dabop includes some factual evidence on that: «Thus if you have two active wires and a neutral wire you have two lots of single phase or "two phase"»

It's you psionl0 who doesn't know about power supply but as John Citizen knows it. Now you're looking a few things you might understand in Wiki. Good for you. The bit about "autotransformer" you wrote gives that away, as you couldn't know how to deal with that concept within this discussion, then you threw the fable above.

Anyway, you're browsing wasn't totally useless, as you now can understand why taking 240V and using progressive isolation through steel cores to generate a "240-phase system" of an assortment of voltages averaging 1 volt would be splitting further and not polyphasing.

And charming as it is the people from Oz -except a few-, call a split-phase system that way and avoid using two-phase in a more international setting, like this one.

Certainly here there's someone who tried to take the "two-phase" bit and built it into an electric theory. And, guess who? it was you, psionl0, who'll never budge no matter how wrong he is.

 

[Dabop]

And that is probably the case with the typical American household too (apart from their 240V ovens etc).

However, 3 phase electricity has the unique advantage that the total instantaneous power consumed by a 3 phase appliance is constant (instead of cycling at twice the mains frequency). You can imagine how that would save on armature stress on a heavy duty motor.

This is mainly an industrial issue but 3 phase motors (and similar appliances) also have advantages in some households as well. That is why I wondered about US households that wanted a genuine 3 phase power in the OP (no problem for the rest of the world of course).

yes, hence my reference in an earlier post to solid versus floating neutrals, this is one of the advantages of balanced 3 phase loads - delta wound versus star, all these debates (and the dis/advantages of each for its applications) seems lost in the us model of power supply- even little things like reversing a motors direction of rotation, all seem just that little bit harder using the 110/220v system

 

[ceptimus]

It used to be difficult to run a three phase motor when you only had a single phase supply. You could rig something up with capacitors - but the capacitors had to be carefully chosen to suit the motor and even then it wasn't very good.

One way of doing it was to use a universal single phase motor mechanically coupled to a three phase motor used as a generator - that worked if you could get the thing to run at the right speed, or you weren't very concerned about the frequency of the three phase that you were generating.

I think there was a sort of hybrid rotary converter that had a commutator one end of the shaft and slip rings at the other with at least some of the windings connected to both. I know they were used to convert AC to DC and vice-versa but I'm unsure whether they could directly convert single phase to multi phase without needing additional windings or slip rings.

Of course, nowadays with microcontroller driven solid state inverters, it's pretty simple to drive a three phase motor from a single phase - providing, of course, that the single phase supply is capable of delivering the required amount of power. Three phase motors are often now driven by inverters even when three phase supply is available - the advantages of being able to vary the running speed and provide soft-start and similar often outweigh the extra cost of the inverter.

 

[aleCcowaN]

However, 3 phase electricity has the unique advantage that the total instantaneous power consumed by a 3 phase appliance is constant (instead of cycling at twice the mains frequency). You can imagine how that would save on armature stress on a heavy duty motor.

Good. Wikipedia will make you wise if you stick to what it says. Constant power is not an "unique" advantage (direct current motors, to name the simplest, have the same advantage). The problem isn't "armature stress" either, but smooth operation.