Can we stop calling it 220?

[Alchymist]

Wouldn't you also need a few capacitors? Otherwise you would only delay the current. We didn't really cover delay lines that much in class though. The wavelenght of 10GHz should be just over an inch I know 1/4 wavelength is a short and 1/2 is an open but I'm not really sure what happens on longer cables. I would think that every 1/4 and 3/4 would look like a short and 1/2 and 1 would look like an open but I'm not sure. I know there are lab setups with a piece of waveguide that was slotted so you could move a detector back and forth to measure the standing wave but I never got to use one.

I would like to take a RF class with a lab. The class I had was only theory. I don't understand RF all that much but the little I did grasp from that class certainly helped with other classes. Especially amps and why you get max power when the impedances match.

I am starting my BSEE in the fall and hope to finish before I retire.

Wouldn't you also need a few capacitors? Otherwise you would only delay the current
Capacitor in one leg could replace inductors. If using all inductors, one must be long enough to delay the waveform by 120 deg, and another to delay it by 240 deg. If using capacitors, one capacitor to shift + 120 deg and one inductor to shift it - 120 degrees. Problem arises when you introduce the load, which can be resistive, inductive, or capacitive, or any combination thereof, thus throwing your network out of balance. Changing the inductor and capacitor to bring it back in balance works for that load. Change the load values,and you have to rebalance.

When you get to higher frequencies, inductive circuits have stray capacitance, and capacitive circuits have stray inductance that you have to contend with. Murphys law. Really come into play in electronics: Amplifiers oscillate and oscillators amplify.

If you really want to understand phase, spend a few months learning the intricacies of one of these:
http://oakbluffclassifieds.com/Funn...0C-system-w-s-parameter-test-set-sweeper.aspx

By the time you get to Smith charts and polar display on one of these babies, you are either quite knowledgeable or hairless, one or the other.

 

[Sr. WiNdTeCh]

I couldn't read all 11 pages but if you must know the voltage comming to your house isn't 110 or 120.... your looking at the RMS voltage... the "usable" voltage... you are most likely getting around 160-170....

Sorry I had to do it! (please let me know if this was already said!)

 

[Alchymist]

I couldn't read all 11 pages but if you must know the voltage comming to your house isn't 110 or 120.... your looking at the RMS voltage... the "usable" voltage... you are most likely getting around 160-170....

Sorry I had to do it! (please let me know if this was already said!)

1.414 X RMS = peak, X 2= peak to peak voltage, true of any sinusoidal waveform. And ? The RMS value is used because that's what does the work; used in power calculations.

 

[Zeke]

Hey, I bet as a total novice, I can clear this up. 3 phase is dependent on each phase to operate. Single is not.

So, how did I do?

 

[Alchymist]

Hey, I bet as a total novice, I can clear this up. 3 phase is dependent on each phase to operate. Single is not.

So, how did I do?

Close, no cigar. Lose one phase from 3 phase, no go. Lose one phase from single phase, no go.

 

[Sr. WiNdTeCh]

1.414 X RMS = peak, X 2= peak to peak voltage, true of any sinusoidal waveform. And ? The RMS value is used because that's what does the work; used in power calculations.

I don't know how to respond to this other than, I did the math and then gave the answer without the formula...

 

[Zeke]

Close, no cigar. Lose one phase from 3 phase, no go. Lose one phase from single phase, no go.

Pretty funny. I aimed my analogy at the 2 phase proponents. Or was that obvious?

I'm just havin' fun and learnin' a lot.

 

[Sr. WiNdTeCh]

2 phase, is well split phase... which is single phase.... pretty weird huh...

 

[cnc-me]

Close, no cigar. Lose one phase from 3 phase, no go.

Most of the time this is true, but I have seen 3 phase motors lose 1 phase and
keep running, especially with multiple motor machines.
The motors will act like a phase converter for each other.

 

[Alchymist]

Most of the time this is true, but I have seen 3 phase motors lose 1 phase and
keep running, especially with multiple motor machines.
The motors will act like a phase converter for each other.

Then it didn't lose a phase, did it.

 

[Steve from Socal]

Once a three phase motor is running it will indeed run on two legs, this is where the term 'singling phasing' comes from. As I mentioned way back in the first 100 or so posts. I have had a few that did this, most were single motor installations. All my bigger machinery has had current sensors monitoring every motor.

Steve

 

[Alchymist]

Once a three phase motor is running it will indeed run on two legs, this is where the term 'singling phasing' comes from. As I mentioned way back in the first 100 or so posts. I have had a few that did this, most were single motor installations. All my bigger machinery has had current sensors monitoring every motor.

Steve

So what happens when you stop it and try to restart it?

 

[A_Pmech]

Another 1,000 replies and this thread will be more epic than the divining rod thread on PM.

 

[61falcon]

i learn so much while surfing on the world wide web.

 

[cnc-me]

Then it didn't lose a phase, did it.

Just the incoming line lost one phase.

 

[JimDon]

''So what happens when you stop it and try to restart it? ''

You can indeed start it again, with the leg dropped out, but it takes a mechanical fix -- not an electrical one!
Anybody know this trick?
Cheers,
JimDon

 

[Steve from Socal]

''So what happens when you stop it and try to restart it? ''

You can indeed start it again, with the leg dropped out, but it takes a mechanical fix -- not an electrical one!
Anybody know this trick?
Cheers,
JimDon

Pull Start!

Steve

 

[JimDon]

DING DING DING DING!
We have a winner.
You must be old, or really really been around a lot to know that!
I actually made a pull rope with a handle on it to wrap around the shaft and start my 3-phase motor. Works pretty neat, but you have to spin it up fast to get er to run and keep spinning.
CHeers,
Jim

 

[cnc-me]

Pull Start!

Steve

Also works on Single Phase motors with bad start windings.

 

[Steve from Socal]

Well I am 50 and 11.5/12ths

I have been playing machines for a long time and in a former life was a plant manager for a large CNC wood shop. That meant I was the guy who crawled through snow drifts of sawdust and rebuilt 25000RPM spindles.

Steve

 

[Alchymist]

Also works on Single Phase motors with bad start windings.

Some of the guys who built phase converters from 3 phase motors use a pull rope to start them also.

 

[JimDon]

Well Steve I don't consider 50 to be old at all, but those 25,000 rpm spindle repairs tells me you've been around the block more than a few times.
Cheers,
Jim

 

[cnc-me]

Well I am 50 and 11.5/12ths

I have been playing machines for a long time and in a former life was a plant manager for a large CNC wood shop. That meant I was the guy who crawled through snow drifts of sawdust and rebuilt 25000RPM spindles.

Steve

Been into few myself....
COLUMBO'S PERSKE'S
And even some C.O. Porter 20,000 Rpm belt drives.

 

[cnc-me]

Some of the guys who built phase converters from 3 phase motors use a pull rope to start them also.

Not to elegant but it works.
Capacitors are the better way though.

 

[Steve from Socal]

This is already way off on a tangent so,

The shop was an eclectic mix, we made slot machine cabinets forIGT and Balley's, speakers for CV and JBL and, TV cabinets for projection screen TV's. The back bone of our work were two Shoda 4 head routers with piggyback drill heads, these were double pallet machines. We had a profile wrapping line to laminate boards and a miter fold line. The board was anywhere from 61x120" and up, all this was cut using optimization on a CNC panel saw. The Shoda main spindles were 25000RPM max at 400Hz and they ran 16-24 hours a day 5 days a week. It was fun while it lasted, first Mexico, then the Philippines and, finally China do it all now.

My former boss actually went to China and ran factories there for 8 years. He came back a couple years ago between gigs and got into making guitars right here in Van Nuys. I went over to visit and mentioned a Heian router for sale on ebay at Reliable. I knew as soon as I saw the router it would sell cheap. Reliable sells mostly metal working and hobby or light industrial, this was definitely not something a guy would put in his garage. The router is a 4 head double pallet machine with 2 5 spindle drill packs. New in 1998 this was a 400K machine. Lance bought it for a song, I have seen Reliable get more for a Bridgeport mill.

I left for Kansas the day after he won the auction. When I got back he had it powered up but it had been really abused. It came out of a cabinet shop in Bakersfield and a spindle was trashed. The labyrinth washer on the spindle was dark blue from heat and had about an 1/8 inch of play. Now another little tidbit; Heian routers are marketed in the US by a company we sued for design flaws on our profile wrapper, made by a German firm they are a subsidiary of. So I had to source or make what ever was needed. Another little bit about machine tool builders; they like to make as much as possible proprietary. In the end; the spindle was OK and the bearings failed due to clogged oil passages. It was at least 12 years since I have done a spindle but this thing just purrs at 26000 RPM.

This machine is now making bodies and necks for some great American made guitars. http://lslinstruments.com

Steve

 

[Sr. WiNdTeCh]

DING DING DING DING!
We have a winner.
You must be old, or really really been around a lot to know that!
I actually made a pull rope with a handle on it to wrap around the shaft and start my 3-phase motor. Works pretty neat, but you have to spin it up fast to get er to run and keep spinning.
CHeers,
Jim

Im 25 and knew the answer. ive had to do it with a fan before.

 

[kaffine]

I'm still thinking you will need both capacitors and inductors to build a delay line. Inductors in series and capacitors in parrallel. If you only use inductors then only the current would lag the voltage. If you just used capacitors only the voltage would be delayed. Also a purely inductive or a purely capacitive circuit will only cause a 90º phase shift.

This is were I think some of my college classes left something out though. I remeber building and testing circuits with inductors and capacitors and looking at the phase changes and taking an inductive circuit and adding a capacitor and bringing voltage and current back into phase. What I don't remeber is comparing it to the source. Both the voltage and current should have been slightly delayed from the source after the LC circuit. They said that the capacitor cancelled the effects of the inductor to bring the phase angle between voltage and current back. Looking at it now I don't think the capacitor cancelled the effect of the inductor I think it just delayed the voltage making it look like it cancelled if you compared the current and voltage waves to each other. If you compared them to the source though it should still have the delay. Hopefully this will be covered better in the EE classes.

 

[jawnd393]

I've called it 110/ 220, 117/234, 120v/240 or 125/250. My measured voltage is close to 125/250. Whatever the present code and/or on the labeling of new elect wiring equipment calls it, is probably what we should call it.

The way I see it is single phase power comes to the house, but we take the line from the center tap of the transformer and call it neutral. Referenced to neutral the other 2 lines are different phases.

 

[gatchel]

Call it what you want, but really, who gives a ****.


I am suprised that the mods didn't lock this thread days ago as it's only real purpose as of now is to take up space on the servers garagejournal resides on.

What's next? A tread slamming people for improper spelling, poor grammar, and im proper use of punctuation? Really come on...

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

Someone else mentioned that this was the best post, I agree.

 

[Justanoldguy]

Call it what you want, but really, who gives a ****.

Well I do.
There is a lot of useful info here.
Like any thread, you sift through it and take what's good.

Are you the thread policeman now?

 

[MrMark]

It's called split phase by the electric company, according to "experts" on here. What happens when you "split" something? How many of that something do you have? I thought so. Perhaps this is just another unfortunate name. They say "it looks like two phases but this is a mistake, it's really one." I say it depends where you look and your definitions of phase.

There are two inverted waveforms available for use at the panel, although not across the same device. Unless you are prepared to carve out an exception to the definition of a phase, then inverted waveforms are 180 degrees out of phase with each other and therefore of differing phase. These waveforms are used at the panel exactly like they are shown in the oscilloscope.

You can have a 120 V device running on phase A and a different 120 V device running on phase B (inverted).

Most of these posts are irrelevant as I never argued it was generated as other than single phase. I only maintained from the beginning that there were two distinct phases available at the panel with respect to neutral. Some, don't want to call these "split" phases differing phases because they cannot get past the fact that only a single phase is generated. According to these industry insiders, inverted waveforms are of the same phase, at least when single phase generation is discussed.

 

[MrMark]

Wikipedia explains polyphase (two phase, three phase, or more) as well as single phase (or split phase) pretty well:

A polyphase system must provide a defined direction of phase rotation, so mirror image voltages do not count towards the phase order. A 3-wire system with two phase conductors 180 degrees apart is still only single phase.

http://en.wikipedia.org/wiki/Polyphase_system
http://en.wikipedia.org/wiki/Split-phase_electric_power

This pretty much sums it up as I've been saying from post one. It's definitional by the utility company and the NEC. They chose to define two phase conductors 180 degrees apart as still only single phase because, like many here, they are focusing on the generation and can't or won't look at the user side of the "split" phase. I don't agree with that because it is contrary to the definition of phase. That's all there is to it.

 

[Alchymist]

I'm still thinking you will need both capacitors and inductors to build a delay line. Inductors in series and capacitors in parrallel. If you only use inductors then only the current would lag the voltage. If you just used capacitors only the voltage would be delayed. Also a purely inductive or a purely capacitive circuit will only cause a 90º phase shift.

This is were I think some of my college classes left something out though. I remeber building and testing circuits with inductors and capacitors and looking at the phase changes and taking an inductive circuit and adding a capacitor and bringing voltage and current back into phase. What I don't remeber is comparing it to the source. Both the voltage and current should have been slightly delayed from the source after the LC circuit. They said that the capacitor cancelled the effects of the inductor to bring the phase angle between voltage and current back. Looking at it now I don't think the capacitor cancelled the effect of the inductor I think it just delayed the voltage making it look like it cancelled if you compared the current and voltage waves to each other. If you compared them to the source though it should still have the delay. Hopefully this will be covered better in the EE classes.

One can build a circuit to shift phase from 0 to 360 degrees using wire only. It's done all the time with cable in the electronics industry.If you send a sinusoidal waveform into a length of cable, down the cable a distance of 1/2 wavelength of the frequency of the waveform, the phase will be 180 out from the source. Now, take a splitter and inject the same waveform into it, and compare the output of two cables cut of the splitter at, say, 1/4 and 1/2 wavelength. You will see a 90 deg difference in the two waveforms at the ends of the cables. By cutting the cables appropriately, one can obtain any phase shift desired. Of course at 60 Hz, it's gonna be a long set of cables!

 

[gatchel]

Well I do.
There is a lot of useful info here.
Like any thread, you sift through it and take what's good.

Are you the thread policeman now?

No. I could only wish for such a title.


Come on, Really... Have you been able to determine which is the "proper" way to refer to you home electrical system? Are they legs or phases? I still haven't seen a definite answer...here that is...

 

[skiingman]

They aren't my definitions, they are the definitions. As you pointed out, it is the way the NEC defines them. I am not the NEC.

Your definitions are your definitions. Mislabeling a leg as a phase is apt to cause confusion. If a single phase system is two phase in your definition, what do you call an actual two phase (mostly obsolete) system?

The conventions of the NEC and the definitions of physics often diverge. This is only a problem when people who don't really understand what they are talking about get to being obstinate.

An electric motor in a single phase 120 or 240 volt circuit will not start unless it has additional circuits because there is no actual phase lag that creates the revolving magnetic field to start it.

A 240 volt NEC "single-phase" motor is connected to two wires with waveforms providing potential 180 degrees out of phase from each other. That this phase relationship cannot start a motor doesn't change the physical reality that the two wires are 180 degrees out of phase.

If there were real phases available, then these starting circuits would not be necessary as they are not necessary when real phases are available to start the motor.

If you developed a two phase power system with each phase 180 degrees apart, the motor would not start. Despite "real" two phase power. There is no compelling engineering reason to build such a system, but I could build a proof of concept in ten minutes. WHY the motor doesn't start is simple physics...the field doesn't rotate.

NEC two phase power refers to ancient systems with phase angle 90 degrees...allowing simple motor starts.

The motor says that single phase mid-point neutral is still single phase.

The motor demonstrates that a directional magnetic field can't be created with a 180 degree phase relationship given identical waveforms. No more, no less.

Despite the assertions that trade vernacular is holy, the conventions of physics are both more complete and more widely held.

 

[Alchymist]

They aren't my definitions, they are the definitions. As you pointed out, it is the way the NEC defines them. I am not the NEC.

The conventions of the NEC and the definitions of physics often diverge. This is only a problem when people who don't really understand what they are talking about get to being obstinate.

A 240 volt NEC "single-phase" motor is connected to two wires with waveforms providing potential 180 degrees out of phase from each other. That this phase relationship cannot start a motor doesn't change the physical reality that the two wires are 180 degrees out of phase.

If you developed a two phase power system with each phase 180 degrees apart, the motor would not start. Despite "real" two phase power. There is no compelling engineering reason to build such a system, but I could build a proof of concept in ten minutes. WHY the motor doesn't start is simple physics...the field doesn't rotate.

NEC two phase power refers to ancient systems with phase angle 90 degrees...allowing simple motor starts.

The motor demonstrates that a directional magnetic field can't be created with a 180 degree phase relationship given identical waveforms. No more, no less.

Despite the assertions that trade vernacular is holy, the conventions of physics are both more complete and more widely held.

BREAKTHRU -simple 4 phase power system . Details to follow on Monday.

 

[Sr. WiNdTeCh]

They aren't my definitions, they are the definitions. As you pointed out, it is the way the NEC defines them. I am not the NEC.

The conventions of the NEC and the definitions of physics often diverge. This is only a problem when people who don't really understand what they are talking about get to being obstinate.

A 240 volt NEC "single-phase" motor is connected to two wires with waveforms providing potential 180 degrees out of phase from each other. That this phase relationship cannot start a motor doesn't change the physical reality that the two wires are 180 degrees out of phase.

If you developed a two phase power system with each phase 180 degrees apart, the motor would not start. Despite "real" two phase power. There is no compelling engineering reason to build such a system, but I could build a proof of concept in ten minutes. WHY the motor doesn't start is simple physics...the field doesn't rotate.

NEC two phase power refers to ancient systems with phase angle 90 degrees...allowing simple motor starts.

The motor demonstrates that a directional magnetic field can't be created with a 180 degree phase relationship given identical waveforms. No more, no less.

Despite the assertions that trade vernacular is holy, the conventions of physics are both more complete and more widely held.

actually if you have a 120volt single phase motor you will need a starter capacitor which will give a 90degree shift and basically make another phase to start the motor and then a centrifical switch will take the capacitor out of the circuit so it runs on one 120volt phase. So you dont need 180degrees out to work.

 

[skiingman]

So you dont need 180degrees out to work.

Read that again. 180 degrees specifically DOES NOT work without a shaded pole, capacitive start, etc. Despite this, it still is defined by physics and math as two phases.

 

[big.jim]

i nearly lost the thread on this but if your voltage is lower your power usage goes up so your bill goes up too not down

 

[rabidsquirrel]

i nearly lost the thread on this but if your voltage is lower your power usage goes up so your bill goes up too not down

Err, read up on Ohms Law.