Split phase power in North America (22 - Electricity Distribution)
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- čas přidán 4. 08. 2024
- What's the advantage of split phase power and why do they use it in North America? Learn how to distinguish the various wires on utility poles, and how a pole transformer works in split phase setups.
Full edX course with interspersed practice problems to help you learn:
www.edx.org/learn/electricity...
Aaron Danner is a professor in the Department of Electrical and Computer Engineering at the National University of Singapore.
www.ece.nus.edu.sg/stfpage/el...
Video filmed and edited by Cheryl Lim.
@randomcheryl
That is so different and interesting for someone who lived in Europe for his whole life. Here we don't use the split phase system at all. In most of the EU you get three phase 230/400V service. In old houses the service can be single phase 230V, or if you want to have very low power limit like 5kW to get cheaper service, you can also ask for just one phase. But even in that case they will give you 3-phase wiring up to your distribution board, so everything is 3-phase-ready if you ever wanted more power in the future. The transformers here are definitely more than meets the eye ☺ Most of them are huge and feed hundrets or thousands of houses, through a dedicated low voltage power lines. Thus no high voltage running along every street, those lines mostly run through fields in rural areas, and underground in cities. So when I watch videos with "transformer explosions" from the US I'm always with my jaws opened, as here you see arcing power lines very very very rare.
THIS HAS SOME MISTAKES, BUT I POSTED TO MY FB PAGE AS WE (PAHRUMP, NV) ARE HAVING TROUBLE (DIRTY POWER) IT DOES CONTAIN A LOT OF GOOD INFO.
great explanation! thanks
Thanks for explaining the primary side winding of a split phase distribution transformer! Hard to find information on it.
In France you can have 400V in your oven as the street grid is 230/400 and you can get a tree phase service !
If the two outer bushings on the secondary side are 180° out of phase relative to the centre tap means that whilst one is +ve 120V the other is -ve 120V and would result in potential difference of 0V. They would cancel each other out. We know that this is not the case because when we test the voltage we have 240V. Therefore the outer bushings are not 180° out of phase relative to the centre tap. By centre taping the secondary windings of a transformer what you are doing is taking a point on winding that divides the number of turns in half approximately. The result would be a potential difference of 120V between either outer bushing and the centre tap. Both of these voltages would be in phase thus single phase into and single phase out of the transformer. What is split is the voltage but the phase remains unshifted.
4:45 This information is not true for Europa. In Austria and Germany you get three phases to your house or flat. Four wires: 3 hot called L1, L2, L3 and neutral called N or PEN. Voltage phase to phase is 400 V. So you can run a 3-phase motor without any problem. Very handy for a workshop or a waterpump.
*UTILITY:* _"We're giving you single phase service."_
*CUSTOMER:* _"But I have 2 hot wires coming into my house."_
*UTILITY:* _"Yes. It's one single phase from the transformer, but's it's split."_
*CUSTOMER:* _"Oh, so it's just a Y-connection, and I have 2 of the same hot wires"_
*UTILITY:* _"No, each of your hot wires are 180 degrees out of phase with each other."_
*CUSTOMER:* _"Soooooo, in other words, I have TWO PHASES - which means I have TWO PHASE SERVICE."_
*UTILITY:* _"Well, I guess it's more like your single phase is not really split - it's more like two halves of a single phase."_
*CUSTOMER:* _"So, I have two half-phase single phase service??"_
*UTILITY:* _"Uhhhhh...... You're gonna have to call my supervisor."_
Pretty much sums up my thoughts on the matter perfectly.
8:29 I think it's a Fibre optic cable, not a static wire. It is used for communication between substations.
At 7:40 you say some customers get their service underground with a hot and neutral wire coming down the pole. Are these lines that come DOWN the pole going TO a transformer on the ground near the house, or are they emanating from the secondary winding of the pole transformer going directly into the house? Thanks.
@ 2:44 you call one of the primary bushings "a neutral" . Could you expound on this a bit. Is the term "neutral used for any return line, even if it's NOT a post-load line and it's at high voltage?
As you are a teacher, there is something I wish you would explain to your students. When you say that the split phase is 180 degrees out of phase, you must make sure that it is known “when viewed on an oscilloscope when neutral is connected to the common point on the scope” This condition does not truly exist. When you show the two sine waves for 120 volts, the resultant voltage would be zero volts. 120/240 volts is single phase. The connection points are not called phases until you are in multiple phases. They are Line1 and Line2.
If you would like, I can link you to videos explaining why 180 degrees out of phase is very much incorrect in the real world. Respectfully, Kevin
Yes. I would greatly appreciate any videos that clearly explain WHY the 2 hot lines are 180 degrees out of phase. Thanks for your input.
I hope this instructor doesn't try to display in-phase waveforms on a scope unless he has an isolated scope. Otherwise, kiss your front end goodbye.
@@Festus2022 Watch the video made by Dave Gordon named 120/240 V In-Phase or Out of Phase
Great explanation, we just wondering how many household that 1 transformer feed?
How they connect?
On your demotrated figure, it feeds 2 houses , we guessed:-)
What about if it is a 100 House community? We need 50 transformers?
Thanks for all inspirational videos👍👍👍👍
One minute into the video my observation is ( this is the European method). Build with hindsight after North America.
Why do we have 120 volts to ground systems in the US? Easy answer, politics and money. Thomas Edison the inventor of the light bulb, made his lights to work on 120 volts DC. And was installing 120 volt DC power systems to homes. Tesla was working with AC systems and decided it was better to power homes at 240 volts AC. As things always happen a Standards group had been formed and they were so inclined to decide that 120 volts to ground would be the standard. BTW, most of the Standards group were friends of Edison.
Tesla did not decide that, it was one of the engineers as Westington that made a working generator out of the general ideas Tesla had.
Edison didn't invent the light bulb, he was the man who got the first commercial success. The reason for the split phase is that Edison couldn't find any generator making more than 120V when he started the electrification campaign, but with a "common neutral" two generators could share the neutral cable saving 25% copper, while making load balancing between the generators easier. Adding a centre tap to the transformator winding allowed existing DC systems to shift seamlessly to AC instead.
The channel "Kathy loves physics and history" have an excellent series of videos that covers the whole development from Voltas battery and the early experimentation to the European three-phase system now used globally.
“Multi point grounding system” “Neutral to Earth Voltage”
It is not that it is 180 degree out of phase.
In phase when measure consecutively from either L1 to L2 or L2 to L1. Single phase.
I don’t understand because u do realize u just showed a primary hot wire directly to a neutral that’s tied to ground on ur primary side and I think you should double check ur book
Probably less likely to get killed. Not withstanding the remarkable amount of flim-flam in that statement alone, 'probably', 'less likey', no except in edge cases. Universally accepted real world scenario tests have shown 120VAC systems to be just as fatal as 240VAC systems. The simple proof of this is in countries with similar levels of refinement of electrical standards, as a proportion of population the USA has a high rate of shocks and electrocutions compared to those countries using 220-250VAC. If 120VAC was safer it would be reasonable for the situation to be reversed or at least have similar rates per population.
I really wish this myth would go away. It wasn't an accurate statement decades ago and it's even less accurate these days with many countries requiring RCD (GFCI) or at least have implemented regulations that push installations towards having them over time. If you want a marked step in intrinsic safety you need to go quite a bit below 120VAC. For example the UK has a 120VAC-ish standard for use in building sites where the 120VAC supply is centre tap earthed to ensure that should a person come into contact with one of the 'live' legs they will only be exposed to approx 60VAC.
The real reason the USA has 120/240 is backward compatible historical supply arrangements.
Haha yes if someone dies from electrocution at one voltage, it is then hard for someone else to be "more dead". Accidental electrocutions at household voltages are so rare to begin with that I'm not surprised if the overall death rates are similar though. The lethality trend would probably be clearer if comparing 12 kV to 120 V.
@@adanner if anything, electrical caused fires should be more common in the split-phase countries, all else being the same, as any bad connection would have the heat dissipation squared since the current is the double compared to the rest of the world.
Split phase is NOT 180 degrees out of phase. It's a single phase. The hot to neutral voltage is half of the phase.
Higher amps would be more dangerous than lower
Amps is not dangerous, when you start your car it draw 300 to 600 amp, but it's still 12V
Amps is the dangerous part.....voltage does not matter its the amps
And at that DC and ac amps is different study electricity before you comment
@@brandonharris305 DC and AC is not the matter "the AC VS DC" war is over they both kill. I don't talk about HF (skin effect). The current flowing in your body when it become a part of a circuit is a function of the voltage, so the higher the voltage is, the higher the current will be. As the body is a "little" load, the size of the power supply don't change anything, If you press the tip of a non insulated screwdrivers on a 120 V thousand amps capable busbar or on the live wire in a 120V house plug you'll get the exact same shock .
@@lapub. ok
I like the video. But your terminology is making it sound like you have two phases in the home. You have one phase. There are two legs of that single phase in the home.
To je ale debilní systém. 230V/400V je lepší...