2 phase? What is this symbol?

[Kurt Wyberanec]

Looking at a mid 2000s scmi saw and it says 2 under the ~ block on the name plate... is phase? And what does the 2 signify? Is this a 2 phase machine and if so what does that mean? I've seen this as a 3 on many machines too... not my area of expertise.... thanks

[derek labian]

You might post a picture of the plate to get a quick/accurate answer if you have it.

[Michael Schuch]

No motor is going to be labeled 2 phase. It is either 1 phase 120v, 1 phase 240v or 3 phase. So, no, definitely not.

[Phillip Mitchell]

Well....there was/is 2 phase power still in certain, shall we call them “historical” locations - Philadelphia, for example, if I’m not mistaken. From my limited reading on the subject it seems like a problem I would not want to wrestle with and I have many 3 phase machines.

I cannot, however, see any logic behind an SCMI machine having a factory stamped 2 phase motor, but maybe someone else out there has experience.

A few photos would help.

[Rod Sheridan]

Looking at a mid 2000s scmi saw and it says 2 under the ~ block on the name plate... is phase? And what does the 2 signify? Is this a 2 phase machine and if so what does that mean? I've seen this as a 3 on many machines too... not my area of expertise.... thanks

No, it wouldn’t be 2 phase power, 2 phase is a three wire system with a 90 degree phase displacement.

I’ve only seen it in aviation applications…… Regards, Rod.

[Patrick Kane]

Are you sure it isnt a poorly/incomplete stamp of the number "3"? You can do some backwards engineering if you have the KW/HP rating, full load amps, and voltage of the motor.

[Jared Sankovich]

Well....there was/is 2 phase power still in certain, shall we call them “historical” locations - Philadelphia, for example, if I’m not mistaken. From my limited reading on the subject it seems like a problem I would not want to wrestle with and I have many 3 phase machines.

I cannot, however, see any logic behind an SCMI machine having a factory stamped 2 phase motor, but maybe someone else out there has experience.

A few photos would help.

Philadelphia seems to be the most common place to find OWWM with 2 phase motors.

[Erik Loza]

Some of the early Italian machines showed 2-phase on the motor plates. Every one of those I ever saw was a 1-phase machine.

Erik

[Frank Pratt]

2 phase is something we learned about in electrician school, but it's little more than a curiosity and was never used in mainstream power distribution.

[Bill Dufour]

Some old school electricians and EEs referred to 240 volt as two phase. That is not the same as true two phase since it only requires two hot wires not three or four.
Bill D

[Frank Pratt]

Some old school electricians and EEs referred to 240 volt as two phase. That is not the same as true two phase since it only requires two hot wires not three or four.
Bill D

I personally don't know any who do that, but if they did, they'd be dead wrong.

[Greg Funk]

I personally don't know any who do that, but if they did, they'd be dead wrong.Technically, in North America, a neutral and two hots is two phases 180 degrees apart. In some parts of the world they will supply a residence with 2 out of the three phases from a conventional 3-phase distribution system. In that case you have a neutral and two hots 120 degrees apart. Doesn't make much sense in the context of a motor though.

[Rollie Meyers]

2 phase is something we learned about in electrician school, but it's little more than a curiosity and was never used in mainstream power distribution.

In the early days of electricity, 2Ø was the original polyphase power, it's largely disappeared but there are a few hangers on still in existence in Philadelphia, PA, & Hartford, CT.

[Erik Loza]

Photo I took of a CU300 Smart ID plate, circa 2006. Look closely at the motor phasing designation. This is a 1-phase/230V machine.

Erik

475690

[Frank Pratt]

I suspect regional terminology variations.

[Tony Shea]

It is my opinion that it is a single phase motor. Just as Erik points out, some foreign nameplates do have a 2 under the phase box when in fact it should be a 1. Just to be sure you could certainly backwards engineer based on the other information on the nameplate and wire connection diagram.

[Kurt Wyberanec]

Photo I took of a CU300 Smart ID plate, circa 2006. Look closely at the motor phasing designation. This is a 1-phase/230V machine.

Erik

475690

Erik, this is exactly what I am talking about, and in fact also an scmi machine. Do you know for a fact that this is a single phase machine? I'm trying to figure this out because the machine I am looking at states in the auction item description that it is 3 phase however the plate reads exactly like the one you pictured. I know that some manufacturers (as mentioned above somewhere) sometimes will say that 240v single phase power is 2 phases because it is usually 2 single 120v lines combined to 240 (220 230 whatever)....but I don't know if that is what this is designating? The reason I find it curious though is that in my case the machine has a 9hp motor, which typically I would think is pretty big for single phase and it also states it at 30a which would also seem small for a single phase motor that big.

And I was also thinking can that 2 simply mean 2 hot leads, which would be 3 phase then????

Thoughts guys? I appreciate the conversation discussing how the phases work and what not, but really just trying to get an answer as to what the 2 really means on the plate like the one pictured. Thanks!

[Phillip Mitchell]

What model saw is it?

[Kevin Jenness]

Erik, this is exactly what I am talking about, and in fact also an scmi machine. Do you know for a fact that this is a single phase machine? I'm trying to figure this out because the machine I am looking at states in the auction item description that it is 3 phase however the plate reads exactly like the one you pictured. I know that some manufacturers (as mentioned above somewhere) sometimes will say that 240v single phase power is 2 phases because it is usually 2 single 120v lines combined to 240 (220 230 whatever)....but I don't know if that is what this is designating? The reason I find it curious though is that in my case the machine has a 9hp motor, which typically I would think is pretty big for single phase and it also states it at 30a which would also seem small for a single phase motor that big.

And I was also thinking can that 2 simply mean 2 hot leads, which would be 3 phase then????

Thoughts guys? I appreciate the conversation discussing how the phases work and what not, but really just trying to get an answer as to what the 2 really means on the plate like the one pictured. Thanks!

A 9 hp motor drawing 30 amps is 3 phase. It would be unusual to find woodworking equipment with a single phase motor over 5 hp. If you can get a look at the plug or cord 3 phase will have 3 conductors plus ground, single phase 2 hot conductors.

[Warren Lake]

are the amps not voltage dependent. If I take a shaper as an example 9hp will likely be 9 amps at 575 volts. Cheaper to run wire at higher voltage.

[Kevin Jenness]

are the amps not voltage dependent. If I take a shaper as an example 9hp will likely be 9 amps at 575 volts. Cheaper to run wire at higher voltage.

Yes - I was assuming standard 230 volts. Higher voltage would normally require a transformer though.

[Mike Henderson]

Technically, in North America, a neutral and two hots is two phases 180 degrees apart. In some parts of the world they will supply a residence with 2 out of the three phases from a conventional 3-phase distribution system. In that case you have a neutral and two hots 120 degrees apart. Doesn't make much sense in the context of a motor though.

Technically, that is rubbish. In a US 240 volt system, the neutral is not used. You only have two wires with one phase between the two wires.

Mike

[brent stanley]

I've heard of North American 240v systems described as "split phase" . I believe one phase usually goes into the transformer and out the other end are 2 residential 120v lines that are 180 degrees out of phase with each other so 240v between them.

[ray grundhoefer]

Technically, in North America, a neutral and two hots is two phases 180 degrees apart. In some parts of the world they will supply a residence with 2 out of the three phases from a conventional 3-phase distribution system. In that case you have a neutral and two hots 120 degrees apart. Doesn't make much sense in the context of a motor though.

Been an electrician for over 40 years. Never hears anyone call it 2 phase ,either single phase or 3 phase period.

[Terry Therneau]

In my younger days, the phrase "2 phase" was sometimes used by fellow farmers to distinguish an outbuilding which has 220 available vs one that had only single phase 110. I fully agree that both these are more properly denoted as single phase. Just pointing out that the usage of "two phase" is common in certain times and locales. (Southern Minnesota, 1960s). Three phase delta started to become more common on local farms starting in the mid 60s, as farmers added grain dryer setups.

Terry T.

[Warren Lake]

is this the symbol?

475832

[Kurt Wyberanec]

For some reason I cannot edit my post to add this....edit button is gone :eek:

Anyway, here is the plate in question....it is exactly like Erik's plate, it lists as ~2 I typically understand this box to indicate phases, maybe I'm wrong. Regardless, is this is single or 3 phase machine??? As I mentioned it's a 9hp motor so I would tend to think 3 phase, and it is advertised as 3 phase, but the plate confuses me. What do you think??

475887

[Greg Funk]

For some reason I cannot edit my post to add this....edit button is gone :eek:

Anyway, here is the plate in question....it is exactly like Erik's plate, it lists as ~2 I typically understand this box to indicate phases, maybe I'm wrong. Regardless, is this is single or 3 phase machine??? As I mentioned it's a 9hp motor so I would tend to think 3 phase, and it is advertised as 3 phase, but the plate confuses me. What do you think??

475887My take is it is a single phase motor but not quite 9HP. If it was 3 phase the HP would be over 14HP with those numbers.

[Ron Selzer]

Looking at a mid 2000s scmi saw and it says 2 under the ~ block on the name plate... is phase? And what does the 2 signify? Is this a 2 phase machine and if so what does that mean? I've seen this as a 3 on many machines too... not my area of expertise.... thanks

a picture of the cord end or where the wire terminates at on the machine would be a big help

[Dan Friedrichs]

If the only info you have is that plate, I'd say it is a single-phase, 5HP machine (30A @ 230V would be 5HP).

Considering the plate is likely the "truth", I'd bet on that. Where did the idea that it was 9HP or 3phase come from?

[mike stenson]

SCM would understand 3phase. It's the delivery method in much of Europe, although wye.. not delta. (every place I've lived). The 2 could be referring to the split-phase delivery used in the US.

[Kurt Wyberanec]

If the only info you have is that plate, I'd say it is a single-phase, 5HP machine (30A @ 230V would be 5HP).

Considering the plate is likely the "truth", I'd bet on that. Where did the idea that it was 9HP or 3phase come from?

I tend to agree Dan, the other info comes from the lister which is an auction house....The literature I've managed to come up with seems to suggest they offered a 5.5hp motor although they still don't specify the phase it the literature lol. I did find another video online of virtually the same machine a year newer and the person mentions it as single phase. Erik also put up a similar plate and stated that machine was single phase too.

In reality I'd really like it to be single phase, though have been looking for a 7.5hp machine. Regardless, if I manage to get one it would be nice to know my electrical requirement before it arrives lol!

[Greg Funk]

If the only info you have is that plate, I'd say it is a single-phase, 5HP machine (30A @ 230V would be 5HP).

Considering the plate is likely the "truth", I'd bet on that. Where did the idea that it was 9HP or 3phase come from?Depends on the motor. If it's rated at 85% efficiency a 5HP motor would be under 20A. An 85% efficient motor rated at 30A would be 7.5HP

[Erik Loza]

For some reason I cannot edit my post to add this....edit button is gone :eek:

Anyway, here is the plate in question....it is exactly like Erik's plate, it lists as ~2 I typically understand this box to indicate phases, maybe I'm wrong. Regardless, is this is single or 3 phase machine??? As I mentioned it's a 9hp motor so I would tend to think 3 phase, and it is advertised as 3 phase, but the plate confuses me. What do you think??

475887

Kurt, that’s a 4.8hp/1-phase saw. In fact, very likely I or one of my officemates was the original salesperson. The S350WS was pretty much the only saw that would take a 14” blade that was available in single-phase in those days.

Erik

[Kurt Wyberanec]

Thanks Erik!

[Erik Loza]

Kurt, just curious: What are they asking for it?

Erik

[Kurt Wyberanec]

It's an auction so no way to say... what do you think is fair? This one has the dro on the do fence, overhead guard, dado, and arms in good shape. I saw another one of these recently slightly less specd too.

And what did you think of these machines?

Thanks

[Erik Loza]

Kurt, I found that auction. Small world: I know the owner. His shop is here in the Austin area. Didn’t realize he was getting out of the business. Decently sized shop full of Stiles equipment, full staff. Wonder what happened? Maybe covid wiped him out? Anyhow, here is my 2-cents: Look elsewhere. If you were within driving distance, “Sure”, but this machine has zero chance of making it cross-country without some type of structural damage. Shop liquidating and getting out of the biz means people on the shipper’s side will do the bare minimum necessary to just get it on a truck. The only way you could safely transport a fully assembled 10-foot slider with overhead guard any distance, frankly, is by dedicated truck (if you think the other freight quote was high, wait til you see dedicated load cost). We have enough struggles just getting new sliders delivered, which are actually crated properly to begin with.

On a personal note, it seems like your quest for this magical unicorn of slider has been going on for quite some time. Sure, you “might” find something within driving distance but it probably will be a project to get running. I keep thinking back to that member here who bought a used Martin, which seemed to end up consuming his entire life. Maybe that’s what you want? But if you actually want to be cutting panels, I would just bite the bullet and buy a new machine. Delivery will be handled, insured, warranty, actual tech support (at least if Felder, LOL), etc. Just my 2-cents.

Erik

[Scott T Smith]

Been an electrician for over 40 years. Never hears anyone call it 2 phase ,either single phase or 3 phase period.

I have heard older local electricians refer to single phase 240 as "split phase". Has anybody else run into this?

[mike stenson]

I have heard older local electricians refer to single phase 240 as "split phase". Has anybody else run into this?

Yes. Very much so. EE's I work with as well.

[Warren Lake]

Patrick put huge time in that saw. So what hes put out more furniture than most people here since the saw was done. His level of work and attention to detail were above most. One more good person not here who cared about the trade and helped people here.

You make him sound like a victim, when really he set the bar.

[brent stanley]

I have heard older local electricians refer to single phase 240 as "split phase". Has anybody else run into this?

Yup, post 23.

[Eric Arnsdorff]

Yup, post 23.

Apparently, I'm old!! I actually gave up thinking that the US 240 VAC should be 2 phase and went with the "split-phase" terminology. However, if you count the phases in 3 phase power (3 sinusoidal phases 120 degrees out of phase with each other phases) then US 240 VAC is really 2 phase with 180 degree out of phase in terms of the sin wave.

When powering anything with AC power - it is the resulting applied voltage difference that provides the power. So if you argued 2 phase should be 2 lines of the 3 phase (another words 2 lines 120 degrees out of phase versus 2 lines 180 degrees out of phase) then you have a special definition of what these voltages are. The device wouldn't care if it received the right voltage from 2 lines 120 degrees out of phase or 2 lines 180 degrees out of phase. All the attached device sees is a potential difference between the 2 lines.

I realize it isn't typical to refer to "split-phase" or 2 hot lines or whatever you'd like to call it as 2 phase - the end result is the same. Provide the right magnitude AC sine wave voltage difference between the two wires and the device has the voltage it needs. You can call it single phase, 2 phase, split phase, or any other choice words, if the RMS voltage is met then it will run.

[Mike Henderson]

Apparently, I'm old!! I actually gave up thinking that the US 240 VAC should be 2 phase and went with the "split-phase" terminology. However, if you count the phases in 3 phase power (3 sinusoidal phases 120 degrees out of phase with each other phases) then US 240 VAC is really 2 phase with 180 degree out of phase in terms of the sin wave.

When powering anything with AC power - it is the resulting applied voltage difference that provides the power. So if you argued 2 phase should be 2 lines of the 3 phase (another words 2 lines 120 degrees out of phase versus 2 lines 180 degrees out of phase) then you have a special definition of what these voltages are. The device wouldn't care if it received the right voltage from 2 lines 120 degrees out of phase or 2 lines 180 degrees out of phase. All the attached device sees is a potential difference between the 2 lines.

I realize it isn't typical to refer to "split-phase" or 2 hot lines or whatever you'd like to call it as 2 phase - the end result is the same. Provide the right magnitude AC sine wave voltage difference between the two wires and the device has the voltage it needs. You can call it single phase, 2 phase, split phase, or any other choice words, if the RMS voltage is met then it will run.

I guess I'm one of those people who thinks terminology matters.

In the US residential power distribution system, you have a transformer that is center tapped on the secondary. The input to that transformer is single phase and the output is single phase (center tapped). It is absolutely not two phase.

Also, in the three phase system, if you take only two of the three wires, you have single phase. In order to get additional phases, you have to use all three wires, and that will give you 3-phase. When you have three wires, you can take any two and you'll have single phase between those two. There are three possible combinations of the wires (1-2, 1-3, 2-3) and you'll have single phase between each of those three combinations. Those three single phases will be 120 degrees apart.

The fact that in the residential power system you have a center tap line does not create another phase. You have 240 volts across the two "outside" connections on the secondary and 120 volts between either of the "outside" wires and the center tap. But it's all single phase.

When you connect power to a 240 volt load, you use just two wires and it's only possible to have a single phase between two wires.

Please stop this nonsense about residential power systems being two phase. It absolutely is not.

Mike

[Dan Friedrichs]

In the US residential power distribution system, you have a transformer that is center tapped on the secondary. The input to that transformer is single phase and the output is single phase (center tapped). It is absolutely not two phase.

Mike is correct and the above is a unique way to explain "why". A transformer can change the magnitude of a voltage, but it cannot create phase-shifted outputs. Thus, a transformer that has a single-phase input MUST have a single-phase output (regardless of center taps).

If that were not true, and a transformer could create "2 phase" from single phase, then why not 3 phase? Wouldn't that be handy if you could just buy a single-phase to 3-phase transformer? The fact that these don't exist should tell you that this isn't possible, and by extension, it is not possible to create "2 phase" from a single phase.

[Tony Shea]

I guess I'm one of those people who thinks terminology matters.

In the US residential power distribution system, you have a transformer that is center tapped on the secondary. The input to that transformer is single phase and the output is single phase (center tapped). It is absolutely not two phase.

Also, in the three phase system, if you take only two of the three wires, you have single phase. In order to get additional phases, you have to use all three wires, and that will give you 3-phase. When you have three wires, you can take any two and you'll have single phase between those two. There are three possible combinations of the wires (1-2, 1-3, 2-3) and you'll have single phase between each of those three combinations. Those three single phases will be 120 degrees apart.

The fact that in the residential power system you have a center tap line does not create another phase. You have 240 volts across the two "outside" connections on the secondary and 120 volts between either of the "outside" wires and the center tap. But it's all single phase.

When you connect power to a 240 volt load, you use just two wires and it's only possible to have a single phase between two wires.

Please stop this nonsense about residential power systems being two phase. It absolutely is not.

Mike

THANK YOU MIKE!!! Lets cut the crap and end the debate. Mike is exactly correct. The 240V coming into a house is a SINGLE 240V phase with 1 sign wave. Just because there is a center tap for 120V loads does not make it 2 phase. I think it's crazy that a European company would list a 2 under the phase section of the nameplate on a single phase machine. This is a complete misunderstanding of Electricity and worries me a bit about their engineers. I could go on for about an hour why this is all craziness but Mike's post sums it up perfectly.

Having said that, can you find the motor nameplate? I would love to see what the motor says. I would have a hard time believing that the motor has a 2 listed under the phase section of the nameplate. If it does, I would probably trash the thing....j/k

[Rod Sheridan]

Absolutely incorrect.

One 180 degree phase displacement is single phase, and requires 2 wires

2-phase requires 3 wires and has a 90 degree phase displacement

3 phase power requires a minimum of 3 wires and has a 120 degree phase displacement.

Regards, Rod

[Eric Arnsdorff]

This is getting a bit side tracked with the terminology.

Clearly residential "single phase" power has 2 "hot wires" providing AC voltage/power. The actual AC voltage referenced to the center neutral tap does have 2 different sin waves of AC voltage (they are shifted by 180 degrees and you can distinctly see the 2 different sin waves). It is not the same sine wave. If it were the voltage difference between them would be zero. Some of you define phase by the resulting difference between the two having a single AC sin wave. This is true too. But it is produced from 2 lines having a sine wave 180 degrees phase shift between them (or any other out of phase angle). Just like typical 3 phase has a voltage between each pair but is shifted 120 degrees. And yes the accepted terminology is to call using the voltage difference between the two wires as single phase. The single coil of a standard transformer is actually producing a polarity difference as the voltage difference is generated. It isn't the same as the utility producing 3 sin waves out phase. But it is still 2 sin waves out of phase when you reference it to a center tap neutral. We could go on discussing if 3 phase delta loads have 3 single phase loads or if 3 phase wye loads have 3 single phase loads.

This is where it all breaks down with the terminology. What is being counted when you have 3 phase power. If I have 3 phase supply that isn't connected to anything then it really isn't any of the terminology as best I can tell from these arguments. Or is it that 3 phase has to be generated from the source with 3 different devices which are mechanically operating out of phase with each other? Therefore, anything that isn't generated this way can't be called 2 phase or 3 phase, etc.

You can shift phases with transformers as well. They are called phase shifting transformers (you could probably have guessed that from the name). And by the way you can generate additional voltage phases by using inductors and capacitors. But if anything that has AC voltage between 2 legs that is a single sin wave then everything is single phase.

It doesn't matter!

The manufacturer put a symbol on this motor with what is being called 2 phase here - I don't see it actually specify 2 phase on the label. This isn't typical but it was done. Being upset by it doesn't change it.

If I had this item it would cause me to look closer at it to make sure. But it does appear to mean the 2 hot wires providing the AC sinusoidal specified voltage. There is a difference for some loads if it is 2 hot wires or a line and neutral. In addition, some things need both hot wires and the neutral. It's all about the load. I read this indication as saying it is expecting you to connect it to 2 hot AC wires out of phase with each other (in phase would result in the motor not running). I also suspect this was done from someone who was putting a motor for American power have the 2 hot wires used to make 240 VAC at 60 Hz. This motor may not operate from the residential voltage in the country of manufacture and they were simply trying to indicate it differently. That's just my speculation on why. And it's ok.

Maybe we could write a thesis on this label.

[Ken Fitzgerald]

For some reason I cannot edit my post to add this....edit button is gone :eek:

Anyway, here is the plate in question....it is exactly like Erik's plate, it lists as ~2 I typically understand this box to indicate phases, maybe I'm wrong. Regardless, is this is single or 3 phase machine??? As I mentioned it's a 9hp motor so I would tend to think 3 phase, and it is advertised as 3 phase, but the plate confuses me. What do you think??

475887

Contributors can only edit a post for 24 hours after it's posted. Moderators can edit for you.

[Dan Friedrichs]

This is getting a bit side tracked with the terminology.

The whole point of this thread was that the incorrect use of "2 phase" confused the OP and left him unclear what type of power the saw actually used. So the value in using the correct terminology is evident. Had SCMI marked the machine using the correct terminology (1 phase), confusion would have been avoided.



The single coil of a standard transformer is actually producing a polarity difference as the voltage difference is generated. It isn't the same as the utility producing 3 sin waves out phase. But it is still 2 sin waves out of phase when you reference it to a center tap neutral.

The choice to use the center tap as the reference is arbitrary. We could choose to "ground" one of the "hot" legs, and then the output from the center tap and remaining "hot" leg would be:
Vct(t)= 170 cos (t)
Vh2(t) = 339 cos (t)

Now there is no polarity difference, just an amplitude difference. Would you argue this is "2 phase"? No - changing the amplitude is not the same as changing the phase.

By similar logic, what if we added an additional (second) center tap? Would that make this a "3 phase" transformer? No - each tap would just produce a different amplitude, but all signals would be in phase.



This is where it all breaks down with the terminology. What is being counted when you have 3 phase power. If I have 3 phase supply that isn't connected to anything then it really isn't any of the terminology as best I can tell from these arguments. Or is it that 3 phase has to be generated from the source with 3 different devices which are mechanically operating out of phase with each other? Therefore, anything that isn't generated this way can't be called 2 phase or 3 phase, etc.

A simpler way to understand it is to consider one of the key advantages of 3-phase power: ability to produce a field that rotates with time. With single-phase power (which include a center-tapped transformer), the lack of a phase shift means there is no ability to spatially rotate a magnetic field. This is why single-phase motors require a starting mechanism (e.g. start capacitor and centrifugal switch).

So a general requirement for polyphase power is that it provides a rotating field. This enables a polyphase motor to start without a separate mechanism to induce rotation. If a separate mechanism (start winding, centrifugal switch) is required, the system is not polyphase.