Single Phase?

[chris kennedy]

This has been tossed around on other Forums. If it has been here also, please hook me up to a thread link. I'm new.:D

Who came up with single phase for two ungrounded conductors and one grounded? I know there is an almost obsolete 2 phase system, yet have always wondered how 120/240 got that tag.

Thanks

[wtdoor67]

is because if you are talking about a 3 wire 120/240 secondary then it is because it is derived from a single phase primary system. Also it is only capable of operating single phase electrical motors in their normal mode.

Also Chris acquire a Kurtz book and read it cover to cover. It'll help.

Chris, a single phase primary is going to normally be derived from 2 wires. These 2 wires may be any 2 from a Wye system or a Delta system or 1 wire from a Wye plus the system neutral.

[returntotheeve]

When you say obsolete 2 phase system are you talking about delta primary? Delta primary you have 2 primary conductors for single phase. One more gives you your three phase. Three phases between three respective pairs of conductors, AB,BC,CA. As far as the tag of single phase for the secondary side it may be due to the fact that like the single Delta primary there isn't a reference for your "single" phase, in other words three phases in relation to rotation. Haven't thought about it as single phase secondary. Never called it that. Don't be afraid to ask. In fact ask about things you know or think you know. Never turn down info, that guy telling you something you've heard so many times before may ADD something you've never heard before. ALSO, (yes I have more) we had some out of town crews helping with a storm and had a crusty chief lineman, while working a Delta line, ask why we fuse our primary AND neutral. Always ask questions.

[johnbellamy]

Actually,
I believe Chris is talkin about ...SECONDARY voltage.

Maby I'm off base here. Shit, I'm just a Rat. I don't know nothin anyway...:rolleyes:

Single phase 124/240. Chris is a NB, I believe he is saying how can you call it single phase 120/240 when you have two phases on the secondary side each 120 v per leg. Single phase refers to a wye primary system, all though on a delta you require phase to phase, so maybe thats what he getting at. Let us know Chris.

[chris kennedy]

I'm asking about secondary, end user systems.

For example:

I have a 120/208 wye secondary. This supplies end user with 3 phase conductors and a grounded conductor. We call this 3 phase.

Residential 120/240 secondary gives end user 2 phase conductors and a grounded conductor. Yet we call this single phase.

[wtdoor67]

going to give it one more shot.

In the average American system, there is normally 3 phase and 1 phase. There are some other systems but these are what makes up 99.99% of American systems.

A 3 phase system can be defined as any primary or secondary that is capable of producing 3 phases of a nominal voltage that have 120 degrees of separation. Anything less is single phase.

3 phase systems can produce both single phase and three phase. Single phase systems can only produce single phase. There are special devices that can produce 3 phase from single phase systems. These are probably not the norm that most people think of when they speak of single phase.

As I said before, a single phase secondary is produced by only 2 wires. Any 2 wires of a 3 phase Wye or Delta, or the 2 wires consisting of a primary and neutral.

[PA BEN]

I'm asking about secondary, end user systems.

For example:

I have a 120/208 wye secondary. This supplies end user with 3 phase conductors and a grounded conductor. We call this 3 phase.

Residential 120/240 secondary gives the end user 2 phase conductors and a grounded conductor. Yet we call this single phase.
120/240 takes only one primary source to produce. 120/208 takes 3 phases of primary to produce. Or you can say 120/240 from a single pot will only produce single phase. Or it's single phase if only 2 secondary phases will do. Boy that was a mouth full.:eek:

[BigClive]

The 120/240 would suggest a single phase as opposed to two phases from a three phase system. It would suggest perhaps a single phase pot centre tapped to ground so that there was 120V either side to ground/neutral, but 240 across the full winding.

[Hemingray Insulators]

its is single phase because if you were to take an oscilliscope and look at the sine wave on either of the two 120v wires they would be in phase with each other they are not out of phses in relationship to each other, hence single phase. if you did the same for 3 phase you would see 3 waves ofset 120 degrees from each other. hopw that helps and is not confuseing.

[chris kennedy]

its is single phase because if you were to take an oscilliscope and look at the sine wave on either of the two 120v wires they would be in phase with each other they are not out of phses in relationship to each other

I thought they were 180 degrees out.

As for the tag "single phase" the single primary thing makes sense.

Thanks all!

[wtdoor67]

Lineman to Grunt. "Hey Joe, send me up the oscilloscope."

Grunt. "That S.O.B. is messing with me again." "Where is it?"

Lineman. "It's in the bin next to those Jonny balls."

Grunt. "What's it for?"

Lineman. "I got to see if this is single phase or 3 phase."

Grunt. "Oh here it is." (Sends it up on the handline.)

Shortly. Big flash. Kaboom!!!!!!

Lineman. "You dumb ass. You sent me the low voltage oscilloscope. Now it's trashed. That's gonna come out of your check."

Brian, I don't think too many people have a high voltage oscilloscope on their truck. Lordy!

Chris, fess up. Are you really in linework?

[chris kennedy]

Chris, fess up. Are you really in linework?

Never said I was. See my profile.

Here's the PM I sent Tracey before I started posting here. From what I understand she is the only Mod here. If I'm stepping on anyones toes, let me know and I'm history.


Hi Tracey

Greg tells me your the only Mod here. I want to let you know my position before I get my head bit off by the members.

I'm a licensed J-man in Broward County.(non-union) I found this forum while researching last weeks event here. I have an interest in MV and HV applications and installs.

I have a great deal of respect for the FPL troops I work around. I do 2-3 large governmental changes(gen-set transfer switches) a year and work side by side with these guys. I have very little respect for FPL's management.

I am a member of other electrical forums but there are few if any linemen that can answer my MV/HV questions.

So should I bow out now, or do you feel my questions will be welcome?

Thanks for your time.

Be well, play safe
Chris

[chris kennedy]

I have also added a signature to avoid any further confusion.

[wtdoor67]

harm buddy. I just thought you were some apprentice who is to lazy to crack a book. Ask any question you feel like.

Seriously, if you will go to your local library and check out the "Linemans and Cablemans Handbook", it will answer many of your questions.

In the mean time ask away.

However, as an electrician I'm surprised you don't know that there are 120 degrees separation of phases in a 3 phase system. Secondary or primary, no matter the voltage that is the way the stuff works.

[500 KVA]

The two 120 volt phases of a single phase transformer are 180 degrees apart. That is what an oscilliscope would show you.

Hemmingrey, try putting those two wires together and see what happens. They are not the same phase!

[chris kennedy]

However, as an electrician I'm surprised you don't know that there are 120 degrees separation of phases in a 3 phase system. Secondary or primary, no matter the voltage that is the way the stuff works.

Sure, I thought I understood this but there are some threads running on other Forums that have the EE's twisting what we take for granted. If anyone has an interest PM me.

[BigClive]

I have also added a signature to avoid any further confusion.

Hey! Drop the scab bit. The term the big macho linemen prefer to describe us technical guys is "narrowback". :D

Clive the broadbacked narrowback.

[chris kennedy]

Hey! Drop the scab bit. The term the big macho linemen prefer to describe us technical guys is "narrowback". :D

Clive the broadbacked narrowback.

Thanks for the thought my friend, but in the good ole USA I'm a scab.

[johnbellamy]

:D
Hey! Drop the scab bit. The term the big macho linemen prefer to describe us technical guys is "narrowback". :D

Clive the broadbacked narrowback.

Nope.... no complex here? :D

[johnbellamy]

Thanks for the thought my friend, but in the good ole USA I'm a scab.

Chris thanks for lettin me know who I am talking to. Don't pay swamprat no nevermind, he thinks this "SWAMPRAT.COM" but it isn't.

My name is John Bellamy and I am a Union Journeyman lineman. I like that you can poke a little fun at yourself, and I think you are ok with who are as a ground hugger. I do not think you have a lineman complex, so enjoy the site, and if you are good at what you do, think about becoming a union member. It pays better, has better benifits, better training and you can be apart brotherhood that wants better conditions for you and your family.

Don't let swamprat , "THE HIRED GUN" :cool: give you any shit, he posts on everything, and I mean everything.......:D

[johnbellamy]

:eek: :eek: :eek: :eek:
This "Scab" thing has been discussed many times on this board.
Looks to me... like it's a nominclature thing.

In other words..."WHAT the FU$K is a SCAB??"

OK...Let's start it again. A Scab...Ain't a narrowback. That's a given.

To ME.... A Scab,.. is a Union Worker, who crosses a picket line. THAT's a Low life SOB. AND... a SCAB.

A RAT, on the other hand... which I...personally am...
is a "gun for hire".

But...I don't cross Picket lines.

So...
What's Ya'lls Defination of the word "SCAB"?

Your opinion is not how everbody feels, Scab, Rat, Works for me "DUDE":

[T-Saw]

Around here the term rat doesn't get used very often. We just generally say " non-union contractors" The only time I have heard the term scab though, was when someone was discussing the possibilty of someone crossing a picket line.
I would have a hard time cutting someone down behind their back ( i.e. calling them a rat ) and then trying to convince them to organize . I'm sure that would be a nice conversation.....
" Hey RAT... why don't you join the union".....
I know if I went to a Ford dealership and they said
" Hey Dodge rat( or whatever name you want here) , why don't you buy a real car, a Ford .."
I would be less than likely to buy one.

[PA BEN]

This "Scab" thing has been discussed many times on this board.
Looks to me... like it's a nominclature thing.

In other words..."WHAT the FU$K is a SCAB??"

OK...Let's start it again. A Scab...Ain't a narrowback. That's a given.

To ME.... A Scab,.. is a Union Worker, who crosses a picket line. THAT's a Low life SOB. AND... a SCAB.

A RAT, on the other hand... which I...personally am...
is a "gun for hire".

But...I don't cross Picket lines.

So...
What's Ya'lls Defination of the word "SCAB"?

A scab is anybody that crosses a picket line.

[johnbellamy]

Around here the term rat doesn't get used very often. We just generally say " non-union contractors" The only time I have heard the term scab though, was when someone was discussing the possibilty of someone crossing a picket line.
I would have a hard time cutting someone down behind their back ( i.e. calling them a rat ) and then trying to convince them to organize . I'm sure that would be a nice conversation.....
" Hey RAT... why don't you join the union".....
I know if I went to a Ford dealership and they said
" Hey Dodge rat( or whatever name you want here) , why don't you buy a real car, a Ford .."
I would be less than likely to buy one.

First of all I call a rat a rat, swamprat is a "PROUD RAT", and I don't do it behind thier back. T- SAW, a question, who crosses picket lines when unions strike, other union lineman, I don't think so, when Union lineman take a stand for better working conditions, who says we will do the work, other union lineman? I don't think so. So who is doing the work then? "GUNS FOR HIRE" :eek: sometimes companies pay these "GUNS FOR HIRE":D alot of money to "GIT ER DONE" for them to brake Unions right. If any so-called union member crosses, then guess what, he is black balled which now makes him a "RAT OR SCAB" a non union " GUN FOR HIRE".:p

Now you know the benifits of organized labor, rats benifit from it, or trust me, no matter what you think, Rat owners would pay you minimum wage if they could, so please tell me the benifits of working rat, sell me on why rat is better for the best interest of the line trade, better for all lineman.

I am not selling anything, I know that the IBEW BROTHERHOOD, and organized labor in general, is about doing what is right for the working man, letting owners know that we have a voice on working conditions, and barganing power, we don't just have to say thanks, we will take what ever you will give us.

[wtdoor67]

I thought they were 180 degrees out.

As for the tag "single phase" the single primary thing makes sense.

Thanks all!

To my way of thinking the 2 phases of a 120'240 volt house transformer would be 120 degrees out of phase and the mid-point neutral connection would be 60 degrees separated from either 120 volt leg.

Guess I'm gonna have to put this one on Swampgas. He's real technical.

[Hemingray Insulators]

The two 120 volt phases of a single phase transformer are 180 degrees apart. That is what an oscilliscope would show you.

Hemmingrey, try putting those two wires together and see what happens. They are not the same phase!

a POTENTIAL diference does not necisarrily mean a PHASEING difference. you are right you are gonna get some light if you connect those 2 wires but they are NOT 180* apart. what if you had a voltage difernce of 5 volts say one is 120 to ground and one is 125 to ground? multi tap transformer (dont jump on me about it being an unreal situation, its just and example) are you really gonna tell me that because there is a 5 volt difference in this situation they are of different phases?

[Hemingray Insulators]

Lineman to Grunt. "Hey Joe, send me up the oscilloscope."

Grunt. "That S.O.B. is messing with me again." "Where is it?"

Lineman. "It's in the bin next to those Jonny balls."

Grunt. "What's it for?"

Lineman. "I got to see if this is single phase or 3 phase."

Grunt. "Oh here it is." (Sends it up on the handline.)

Shortly. Big flash. Kaboom!!!!!!

Lineman. "You dumb ass. You sent me the low voltage oscilloscope. Now it's trashed. That's gonna come out of your check."

Brian, I don't think too many people have a high voltage oscilloscope on their truck. Lordy!

Chris, fess up. Are you really in linework?

haha thats funny, you are right, i was useing it to try and make a point, because i suspect most linemen at least if they are union had a DC Theory part of their apprenticeship and that hopefully what i said would help them understand better what i was trying to say lol.

[chris kennedy]

Also Chris acquire a Kurtz book and read it cover to cover. It'll help.



I Googled this. There must be more to the title.

[Hemingray Insulators]

I Googled this. There must be more to the title.

kurtz is the name of one of the authors. the name of the book is :the "linemans and cablemans handbook" it think they are on what? the 11th edition?? it was first published in 1928 i belive. its a really good book to have...........i've read it twice already, theres a LOT of things that can be learned about different systems and practices and such.

[wtdoor67]

a POTENTIAL diference does not necisarrily mean a PHASEING difference. you are right you are gonna get some light if you connect those 2 wires but they are NOT 180* apart. what if you had a voltage difernce of 5 volts say one is 120 to ground and one is 125 to ground? multi tap transformer (dont jump on me about it being an unreal situation, its just and example) are you really gonna tell me that because there is a 5 volt difference in this situation they are of different phases?

a potential difference does mean a phasing difference. It just means the farther you get out of phase the larger the potential difference.

For example if placing 2 phases together, if the degrees of difference increases then the amount of volts difference will increase which will be noted by an increase of voltage in your reading. Now the average lineman is going to be using a volt meter to accertain phasing potential. I have never heard anyone state a rule of thumb for going together with a couple of secondary phases. I once asked a meterman, when they were paralleling 2 circuits of 12470 together what they used and he stated they would not put it together if it had more than 6 degrees difference. On secondary we never worried about it if you could see the pots but sometimes when we used a voltmeter there might be a 4 or 5 volt difference but outside of a good sparkle it was no problem. However if there was a 10 or more volt difference with 120/240 I believe you better look things over.

[chris kennedy]

I'm guessing this is it but the name Kurtz isn't on it.

1245

[chris kennedy]

Thanks Greg, yes that is a must have. Here is part of my $700 order this year. I twist tools every day but can't keep my nose out of the books. I'm ordering the Kurtz so I don't need you people.:D

1248

[BigClive]

:D

Nope.... no complex here? :D

Oh dear. Well at least you're using upper and lower case letters this time and not going completely psycho. :confused: