Is that a colorful way of saying one is serial and the other parallel? If so, then you have it. If not... well, I am just trying to figure out what 234v is; never ever heard that before.Originally Posted by Tom Deutsch
Member
Is that a colorful way of saying one is serial and the other parallel? If so, then you have it. If not... well, I am just trying to figure out what 234v is; never ever heard that before.
Member
Yes, that will work! If you really want to put current through your ground. Or you could run it to a copper water pipe; that would work also. (no, you can't do any those things)
Contributor
I think he was specifying 117 volts (rather than 120V) for the hot to neutral and then doubling it for the hot to hot.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
Moderator
Split-phase is a better term to use.
Two-phase is whole 'nuther beast although I understand some Niagra Falls generating plant was initially running two-phase and some buildings in Philadelphia are still using a two-phase system today. Wild stuff.
Member
It puts a small imbalance on the motor windings but not the main feed. The current will be the same in both of the two wires unless the motor has a ground fault.
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.
Member
It has nothing to do with ground. The two winding sections are acting as a voltage divider to provide half voltage to the light.
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.
Member
I guess the real question is do you have your own stamp or not? That is what makes you an "expert!"
[QUOTE=Mike Henderson;2463039]Sorry, not right. What you are doing in your thinking is looking at the voltages in each hot wire to ground (or neutral). But ground (or neutral) is not involved in the circuit. All you have is two wires with 240 volts across them. One sinusoidal voltage between two wires.
If we really want to split hairs, each wire has its own sine wave, and the sine wave from one is offset 180 degrees from the other. Since voltage is all about potential difference in amplitude between the two conductors' sine waves, we get double the voltage difference between the first line (sin) and the second line (sin +180 deg) as they are mirror images of each other as we do in simply comparing either one of the lines versus ground. Residential "split phase" 240 volts is really two-phase. However, it is NOT identical to two phases out of a three-phase system, as the phases in three-phase are offset by 120, not 180 degrees. This leads to a different potential difference between any two leads vs. in a two-phase/split-phase system. If we have the voltage difference between any one line and ground be 120 volts, then in a two-phase/split phase setup, the difference between two hot lines will be twice that, or 240 volts. In a three-phase setup, it will sqrt(3) times that, or 208 volts since the sine waves are not complete "opposites" at 120 degrees offset like they are at 180 degrees offset.
That is incorrect, see the above. Split-phase 240 volts in the US is really is two-phase. That's why there are two hot wires and no neutral. A single sinusoid would have only one hot wire and would have a neutral. We do not have one-hot-and-a-neutral 240 volts in the U.S. They do in Britain, but not here. >120 volt true single-phase here in the U.S. is 277 volts (one leg of 480Y 3-phase), and in Canada it's 347 volts (one leg of 600Y volt 3-phase)Your view is a common misconception about power in a residential application. People seem to think of it as some kind of two "phase" system, with 120 volts for each "phase". That's completely wrong. There are only two wires delivering power to the motor and there is only one phase (or sinusoid) across those two wires.
Mike
You can also find 230 volt "rest of the world" lightbulbs online as well. They cost a few bucks is all. Screw one of them into the fixture, wire the motor for 240 volts, and go with it. Just do NOT forget what you did and put a 120 volt bulb in there someday.
Last edited by Phillip Gregory; 09-03-2015 at 9:09 PM.
Member
Munching on the popcorn.... I figured if I spent the time it took to ready this thread actually working, I'd be financially ahead running it either way. Jesse who's trying to figure out 3 phs convertors, why 3 pole breakers are so expensive, and how many times I have to get lit up before I learn to turn off the electricity before "wiring something real quick" instead of wiring hot.
Only one life will soon be past
Only whats done for Christ will last
Member
I must be a wimp but I always shut off the breaker and use the multimeter to make sure it's actually off before I wire anything. I have seen people who have been "lit up" with a variety of voltages and it's not fun. I don't wish to be in their (sometimes melted) shoes.
Contributor
Please see my comments below: Your misconceptions are common but incorrect.
[QUOTE=Phillip Gregory;2463107]I guess the real question is do you have your own stamp or not? That is what makes you an "expert!"
A very small amount of research on the Internet - even Wikipedia - will demonstrate that the US residential service is single phase.
Mike
[Look here. A quote taken from the article: "...a split single-phase is not a two-phase system."]
Last edited by Mike Henderson; 09-03-2015 at 9:57 PM.
Go into the world and do well. But more importantly, go into the world and do good.
Member
If your are serious, please don't post about things you don't understand; you could get someone hurt.
The poster was suggesting that one of the hots could be run through the lamp to ground instead of to the non-existent neutral. It has nothing to do with the windings. One leg will have a bit more current on it because it is feeding the light.
Last edited by Wade Lippman; 09-03-2015 at 10:47 PM.
Contributor
David does understand what he is saying, although I wouldn't recommend what he suggested. Let me explain it another way.
Suppose you had a load that consisted of two 1 Ohm resistors in series and a 2 volt voltage source. If you measured the voltage across each resistor, it would be 1 volt. (two volts across the two resistors)
Now, suppose you had an LED bulb that required 1 volt and you connected it across one of the resistors. The LED would light.
But the LED has some resistance so you now have a lower net resistance where you use to have 1 Ohm. The 2 volts will still drop completely across the load, but a bit more will drop across the 1 Ohm that doesn't have the LED in parallel with it - let's just say 1.1 volt. That means that 0.9 volts is dropped across the other resistance which is in parallel with the LED.
Basically, for his suggestion, replace each resistance with one coil of the motor. And replace the LED with an incandescent bulb. And make the input voltage 240V. Before you attach the bulb, 120V will drop across each coil. Afterwards, a bit more will drop across the coil without the bulb.
I hope that explains it. While it would work, I would not recommend it.
Mike
[The reason I wouldn't recommend it to most people is that there's a danger if the parallel load is too big (low resistance). In that case, the total load impedance is significantly reduced (increasing the current) and a lot of the voltage gets dropped across the coil that does not have the parallel load. So the net is that what David suggested will work - and is used (as he pointed out) for the starter coil - but could be a problem if the system is not well understood and the parallel load limited.]
Last edited by Mike Henderson; 09-04-2015 at 2:42 PM.
Go into the world and do well. But more importantly, go into the world and do good.
Member
You must have misread the post Wade. He did not say to connect anything to ground. What he said wasAgain, the motor windings are in series and each winding has half the total applied voltage. if you connect a small load (light bulb) in parallel with one of the windings it will then see slightly less than half the total applied voltage. The winding with no parallel load will see slightly more than half. There's no connection to ground.
Edit: Mike, I see you put up a better explanation before I was able to get mine done. For the record, the lamp was Malcolm's point, I was just trying to clarify the connections.
Actually this concept is used all the time to provide half voltage to the start winding when a dual voltage motor is wired for high voltage. That is, the main windings act as a voltage divider (actually an autotransformer because of their mutual inductance) for the start winding when it's connected in parallel with one of them.
Last edited by David L Morse; 09-03-2015 at 10:37 PM.
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.
Member
I apologize; I actually misunderstood the post rather than misread it. The idea of putting a light bulb in parallel to one winding wasn't anything I was prepared to see suggested. In the past people have suggested using the ground as a neutral for small load, so I read it that way.
You were a good sport to take it as calmly as you did.
Contributor
Quite right. Otherwise, the start winding would have to be some complex thing. Wiring it the way you described means the start winding is much simpler and always uses 120V.
Mike
Go into the world and do well. But more importantly, go into the world and do good.
Posting Permissions
Reply With Quote
