creativecars
Well-known member
Bull, yeah, this is pathetic.
In a regular classroom there is a Text, 1 Chief, and lots of Indians.
Here, there is...*&^%$#^&^%$^&&&%$^^
I use the net and a basic book, it has worked so far.
Can we stop calling it 220?
- Thread starter mrb
- Start date
Bull, yeah, this is pathetic.
In a regular classroom there is a Text, 1 Chief, and lots of Indians.
Here, there is...*&^%$#^&^%$^&&&%$^^
I use the net and a basic book, it has worked so far.
wuck
Active member
OK, then let's ignore the voltages for a moment. Use two current probes and an oscilloscope. You'll find only one phase of current, not two inverted current phases.
Now, back to the voltage. You see two inverted voltage waveforms due to the reference point chosen, the center tap. With the right equipment (a differential scope), you can't see any phase difference anywhere, it doesn't exist.
Delete that center tap, and ground one leg. Now, you're in the UK with a single phase 240 volt system. What's the difference? The reference point (Center tap or one leg), not the number of phases.
With the center tap chosen as a reference point, the voltages are going to adjust obeying Kirchoff's laws. In other words, with a current flowing through the transformer secondary the voltages at the opposing legs have to develop oppose polarity (Relative to the center tap) to cancel each other around the loop.
Pat
hofferwood
Well-known member
MWBC= Multiwire Branch Circuit
Fer the folks that want to know
Chuck
Fer the folks that want to know
Chuck
9C1
Well-known member
I have worked for 42 years for an electric utility -- some transmission operating, but mostly distribution operations.
I don't have enough posts on this board to insult anyone by offering the facts. Good luck to all of you.
Terry
I don't have enough posts on this board to insult anyone by offering the facts. Good luck to all of you.
Terry
And if you place the leads from the 'A' leg to the 'B' leg you will see one waveform. Call it whatever you want but the NEC and everyone else calls it single phase power.
Having 10,000 posts doesn't make you right.
. electricians arguing over "who has the biggest wire...."ddawg16
Well-known member
I'm a bit confused here.....your quoting me....but then again, I don't have anything close to 10,000 posts....so maybe your not directing it to me?
So....help us out here....what point were you trying to make?
I am making the point, the number of posts you have, has nothing to do with wether you are right or not. You busted the guys balls cause he had 100 posts.
Hurricane_Whisperer
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I have worked for 42 years for an electric utility -- some transmission operating, but mostly distribution operations.
I don't have enough posts on this board to insult anyone by offering the facts. Good luck to all of you.
Terry
And this is an absolutely brilliant post.
Please feel free to "insult" with facts me anytime you wish. I can handle it or prove you wrong depending on who get the right info. This is known as progress and knowledge developement.
There was a mud engineer on that BP platform out in the Gulf who wasn't allowed to "insult" anyone with facts. Look what happened. Oil Volcano.
Hurricane_Whisperer
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You have stated that residential power is two phases. So a motor wired for 230V is not connected across what you are calling two phases?
You are using a device to try to prove that the single phase power of a residential system is two phases. The instrument measures the voltage in the circuit with respect to time.
I am using a device (electric motor) to prove that you are wrong. Same current that you are measuring with a device is following through the motor that I am using. The electric motor can be connected 120V or 240V and it won't start unless it has a special starting circuit.
A three phase motor or a motor operated on an obsolete two phase system will start without the special starting circuit.
Ever hear a three phase motor when it single phases? This can happen if the relay on the three phase power is burnt up and only a single phase comes across. It sits and hums and doesn't turn even if there is no load on it.
There is only a single phase. There is no way for you to hook up a motor without a starting circuit and get it to run. No definition will change that.
They actually make a device called a phase converter for use on single phase circuits so you could use a 3 phase motor on it.
Hurricane_Whisperer
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Amen.
12 years utility experience. Inside a single phase transformer there is one highside coil and 2 coils on the secondary side of the transformer connected in series. Coils are 120 volt coils connected in series.... At Neutral bushing the coils are connected together. So when you are measuring from one hot leg to the neutral you are just measuring 1 coil and when you measure from the other hot leg to the neutral you are measuring the other 120 volt coil. When measuring from hot leg to hot leg you are measuring the voltage of both coils in series of a single phase. So whats delivered is single phase 240 with the center of the winding tapped. Its referred to as split phase and all to often mistaken for 2 phase. It just splits the secondary coil (use less coils of a transformer to produce different voltages. If you have the ability you can get tap the coil any where and the voltage would be proportional to the primary windings to the secondary windings. Find some schematics of a single phase transformer would clear it up.... This may help also but maybe not.
http://www.3phasepower.org/2phasesystems.htm
http://www.3phasepower.org/2phasesystems.htm
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Steve from Socal
Well-known member
I want some of these transformers that create phases, why did i ever bother with phase converters!
By the way; a three phase motor WILL run on two legs IF it loses the third once running, there is an industry of current sensors made just for this event.
Steve
By the way; a three phase motor WILL run on two legs IF it loses the third once running, there is an industry of current sensors made just for this event.
Steve
hofferwood
Well-known member
But--------Do you know "WHY" it humms????????????????
Cause it Don't know the words
And there was Pace Warehouse before Sam's Club
Chuck
Cause it Don't know the words
And there was Pace Warehouse before Sam's Club
Chuck
Greatbear
Well-known member
I have a transformer with five separate secondaries, and a single primary. I do not end up with five phases.
I don't have any exeperience with them, other then knowing they exist. There is a cost, probably not as efficient either. But if you didn't ask the cost when you were considering 3 phase, they probably didn't tell you.
Its a way to get 3 phase in rural areas. If you are in town, its probably better to just get 3 phase. Its probably easier for the utility to just give you three phase.
ddawg16
Well-known member
??????????????????????????????????????????????????????????????????
??????????????????????????????????????????????????????????????????
??????????????????????????????????????????????????????????????????
??????????????????????????????????????????????????????????????????
Want to try that again?
Hurricane_Whisperer
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Yes.
Static devices do not create phases.
So let it be written. So let it be done.
csargents1546
Well-known member
Like our faucets, red is hot and blue is cold. Basic science says that the hotter of the two colors is blue. Go to europe, the faucets seem backwards to the us.
At the time, it made sense to someone, they passed it on and it just kept on growing.
At the time, it made sense to someone, they passed it on and it just kept on growing.
Open delta is one type, I am not up on all the ways to do it, or the advantages.
Steve from Socal
Well-known member
Coping the text of a post on PM regarding corner grounded delta three phase, the transformer does NOT create a phase. Posted by Peter H an EE who worked for DWP
"Grounded B-phase distribution was popular many moons ago. It is applicable to premesis wiring which is three-phase only.
This system can distribute three-phase, using a conventional 120/240 panelboard.
However, the breakers are required to be special "Delta Breakers", which have a much greater interrupting capacity.
Square-D still makes these breakers, although no new panelboards are approved for new installations, as the NEC hasn't allowed grounded Delta for decades.
In grounded Delta, you still run the B-phase wire, except that it is at ground potential and is tied to the B-phase grounding bar.
You also run the green, grounding wire, too, and that is tied to the protective ground grounding bar."
Steve
"Grounded B-phase distribution was popular many moons ago. It is applicable to premesis wiring which is three-phase only.
This system can distribute three-phase, using a conventional 120/240 panelboard.
However, the breakers are required to be special "Delta Breakers", which have a much greater interrupting capacity.
Square-D still makes these breakers, although no new panelboards are approved for new installations, as the NEC hasn't allowed grounded Delta for decades.
In grounded Delta, you still run the B-phase wire, except that it is at ground potential and is tied to the B-phase grounding bar.
You also run the green, grounding wire, too, and that is tied to the protective ground grounding bar."
Steve
A "delta breaker" a special purpose item that has been prohibited by the NEC since 1978.
Here are a couple of links from the Mike Holt forum & Electrical Contractor about the very subject.
http://forums.mikeholt.com/showthread.php/87215-Delta-circuit-breaker
This one has pics.
http://www.electrical-contractor.ne...ubb/showflat/Number/152376/page/16#Post152376
Steve from Socal
Well-known member
I am going to add a link to the thread I quoted, it has some good info on open delta, corner grounded three phase and Scott T transformers.
Steve
http://www.practicalmachinist.com/v...rs-vfd/three-phase-only-two-wires-wtf-103191/
Steve
http://www.practicalmachinist.com/v...rs-vfd/three-phase-only-two-wires-wtf-103191/
ddawg16
Well-known member
This was your first response to Steve's tongue and cheek comment
'Almost' everyone knows that you can NOT create a 3phase sytem from a single phase using just a transformer....that is why Steve's comment was so obviously 'tongue and cheek'.
You are right about one thing.....your "not up on all the ways to do it". There is NO way to do it....with transformers....Delta or Wye
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Grumpy365
Well-known member
I find this thread funny especially in the light of this previous post calling for using " correct terminology"
http://www.garagejournal.com/forum/showthread.php?t=91993&referrerid=47711
The correct terminology is single phase, per NEC and common practice.
Mr Mark will even admit NEC considers the common residential service single phase.
And if any one who got sucked into the theoretical debate PLEASE relize that if you go to an electrical supply house, talk to an inspector, or talk to an electrician, you will look like a full fledged, card carrying, idiot if you ever refer to 220 as 2 phase.
Stupid stuff like this gives engineers a bad name and labels them as being too intellectual, egotistical or arrogant. ( see previous " Contractor" thread
http://www.garagejournal.com/forum/showthread.php?t=98053&referrerid=47711)
http://www.garagejournal.com/forum/showthread.php?t=91993&referrerid=47711
The correct terminology is single phase, per NEC and common practice.
Mr Mark will even admit NEC considers the common residential service single phase.
And if any one who got sucked into the theoretical debate PLEASE relize that if you go to an electrical supply house, talk to an inspector, or talk to an electrician, you will look like a full fledged, card carrying, idiot if you ever refer to 220 as 2 phase.
Stupid stuff like this gives engineers a bad name and labels them as being too intellectual, egotistical or arrogant. ( see previous " Contractor" thread
http://www.garagejournal.com/forum/showthread.php?t=98053&referrerid=47711)
56nash
Well-known member
WOW, I have had these same fights with marketing guys who can't wrap their heads around wye vs. delta power systems and why when they ordered a wye device they cannot tell the installer just to cut off the white wire and all is good when installed on a delta system. Or why there are power anomalies when you use a delta load on a wye system. I love the engineers don't know anything stuff going on here. I guess education and understanding the concept is trumped by "well I call it...." so now it is changed.
Hurricane_Whisperer
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Which guy is an engineer and trying to call residential 240 two phase?
Never say never, unless you got the answer in your pocket.
If only there was a world wide web of information at our figer tips.
You could have googled open delta.
Open Delta Connection:
The open delta transformer connection can be made with only two transformers instead of three (figure 1-8). This connection is often used when the amount of three phase power needed is not excessive, such as a small business. It should be noted that the output power of an open delta connection is only 87% of the rated power of the two transformers. For example, assume two transformers, each having a capacity of 25 kVA, are connected in an open delta connection. The total output power of this connection is 43.5 kVA (50 kVA x 0.87 = 43.5 kVA).
Another figure given for this calculation is 58%. This percentage assumes a closed delta bank containing 3 transformers. If three 25 kVA transformers were connected to form a closed delta connection, the total output would be 75 kVA (3 x 25 = 75 kVA). If one of these transformers were removed and the transformer bank operated as an open delta connection, the output power would be reduced to 58% of its original capacity of 75 kVA. The output capacity of the open delta bank is 43.5 kVA (75 kVA x .58% = 43.5 kVA).
The voltage and current values of an open delta connection are computed in the same manner as a standard delta-delta connection when three transformers are employed. The voltage and current rules for a delta connection must be used when determining line and phase values of voltage current.
http://www.elec-toolbox.com/usefulinfo/xfmr-3ph.htm
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Alchymist
Well-known member
Yesterday i couldn't spell enginere, today I are one. And so what if I am too intellectual, egotistical or arrogant.? I like it.
We still have them in our substations. You don't need a breaker. We use fused disconnects for lots of stuff. New installations are breaker, ac and dc.
Alchymist
Well-known member
I agree it does not make 3 phase, but you can run 3 phase equipment. One guy said if something like that exists, why did I bother getting 3 phase then. I told him my idea, then was told I know nothing, then things just snowball.
Alot of his here do this for aliving. And ya we are probably saying about the other guy, thats scary. Lot of arrogant people here, again we probably say that about each other.
Another thing that happens, in an effort for people to show how much code knowledge or other knowledge they have they say no thats not possible, when in the world you can do it.
Alot of his here do this for aliving. And ya we are probably saying about the other guy, thats scary. Lot of arrogant people here, again we probably say that about each other.
Another thing that happens, in an effort for people to show how much code knowledge or other knowledge they have they say no thats not possible, when in the world you can do it.
Falcon67
Well-known member
I read the whole thread and decided that I'm going to keep saying "220" because I like it.
open delta is three phase.
when we say 'you cant do that' its not to show off our code knowledge. I could really care less what a bunch of people on the internet think I know or dont know. The idea is to help people get their work done in a safe code complient fashion so they dont hurt themselves, someone else, their property value, or start a fire.