single phase vs. 3 phase need explanation

[wnaplay1647545503]

Can someone dummy down a definition of what the difference is between the 2? Besides that one has 2 more phases. Whats the advantage or disadvantage to each?

[oldman09FZ6]

http://en.wikipedia.org/wiki/Single-phase_electric_power

 

http://en.wikipedia.org/wiki/Three-phase_electric_power

[mmrmnhrm]

Besides the "you're too stupid" response from Dennis, the better response is "Why do you ask?" If you're trying to do something specific, those who need to know the difference either learn it in trade school or college, while those who don't are carefully spoon-fed bullshit as to why you have to buy one (usually the one you don't have available) versus the other, even when it's not in their best interest. On top of that, getting 3phase to a residential application is a PITA (no electric utility I know of makes it a "standard" offering), while getting 1phase from 3phase is a simple matter of how you hook up the wires (though possibly requiring a transformer if you're given certain forms of "delta" power instead of "wye" power). If you're just looking for general eddification, those wiki pages give a sort of very basic overview, but not much more.

[Second Gen]

3 phase is typically installed for efficiency (When you have a location that supports it)

 

We bought an older wave soldering machine (15 years ago) and only had std 220/240 in the building. So we built a capacitor start three phase motor that generated power we needed. As the machine was a power whore I did not like starting the electric motor and was always afraid it would go nuclear (Was a monster and was a big as a small V8).

 

If you do not have 3 phase available @ the location go with std 220/240 volts stuff.

 

Back then it cost about 500 to build the converter and unsure if it would be more today (We also used am old motor).

[MattKatz]

Like has been said already...more specifically why domyou

ask?

[Green Bastard]

Generally 3 phase is used for industrial products (ie machenery, large electric motors like the ones used on pumps and stuff, industrial air compressors, etc), anything designed for the household usually doesn't require 3 phase power, so the question is what everyone else is asking, what are you tryin to get that's 3 phase.

[wnaplay1647545503]

I have and understand why the 3 phase is available. I guess my question should have been why is there an option for the same piece of equipment to be either single or 3 phase.

[MattKatz]

Efficiency and amp draw. Typically three phase if available is cheaper to operate, but at the cost of having everything at a higher voltage.

 

If you don't have 3PH where you are currently, and you're looking at something new, odds are it's in your best Interest to get the single phase unit.

[wnaplay1647545503]

I have the power available and can buy either one.

[RS69]

Typically, three phase machinery cost less, most people cant use it without a convertor. If you buy the same machine as single phase, that is the better deal. Years ago, I bought 10 two post car lifts dirt cheap(very good industrial quailty) because they were three phase. This was a great deal, because I was able to change out the three phase motors to single phase.

[wnaplay1647545503]

So if I get the 3phase for cheaper, is it hard to switch it to single phase? Is it a matter of just not using a leg, and is there any downside of doing this(will it work the same)?

[RS69]

So if I get the 3phase for cheaper, is it hard to switch it to single phase? Is it a matter of just not using a leg, and is there any downside of doing this(will it work the same)?

 

I swapped out the motors to single phase.

[Cordell]

3 phase typically has a lower power draw on larger industrial equipment, thus why it is used in commercial and industrial applications. The two systems are not exactly compatible, more specifically with electrical motors, they are entirly different. Single phase motors can be hooked up to two legs of a 3 phase electrical supply, but not the other way around.

 

Also keep in mind that there are 2 type of 3 phase, delta and wye, wye being the most common and what most people refer to. A delta system is grounded differently causing the middle leg to be a higher voltage.

 

Anyway i don't know what info you are trying to clarify for yourself, but if its something i can answer feel free to PM me.

[Akula]

To answer your original question. Think of the ocean, waves rolling in one after another. Those waves are single phase at a time. Now take 3 waves, and put them right next to eachother. The top of the first wave next to the top of the second wave, next to the top of the third wave. AC is a sign wave but if we could fill in the gaps in between the waves, with other waves, we would end up with current that is closer to DC current. This means that we can use smaller motors and get the same output HP because the input is greater.

 

make any sense?

[MattKatz]

Dude...You need to be a bit more specific if you want help. What are you wanting to do with What exactly. Yes motors can be swapped, but if there is other components, you need to consider voltage of these as well as a lot of 3PH equipment has both single and 3PH components installed.

 

Just spit it out....Damn.

You want help but your making us almost beat the damn info out of you.

[mmrmnhrm]

I guess my question should have been why is there an option for the same piece of equipment to be either single or 3 phase.

Because people don't always have the option of going either way.

A delta system is grounded differently causing the middle leg to be a higher voltage.

Assuming it's been grounded at all. One of the nice things about delta is that in an ungrounded system, one leg CAN go to ground without Bad Things happening.

Bad ocean analogy....make any sense?

No... I kinda get what you're trying to describe, but it's just not doing it. Three ocean waves on top of each other isn't three-phase power, it's a surfer dude screaming "Cowabunga!!!" A better analogy is this:

Start with your ocean, and waves come in EXACTLY 20 seconds apart. Every single friggin' time, like there's a giant dude out there at sea with nothing better to do than send waves in with atomic clock precision. The first wave crests, breaks, and hits the shore while the next two are still coming in. The first wave starts receding as the second begins to build, break, and crash. The first and second are now receding as the third does its thing. Over and over and over. Now what you've got is either two waves building as one recedes hard, or one at its very peak while the other two are falling away from shore. Finally, stick some sort of floating object out there, and watch as it doesn't so much as budge. It just sits there, neither rising nor falling. That is the magic of three-phase power.... the sine waves are aligned in such a way (120 degrees apart) that the sum of all three is ALWAYS zero. Because the sum is zero, you no longer need a neutral wire to carry current back, and one less wire means less cost to install, maintain, and some day decommission that equipment.

You want help but your making us almost beat the damn info out of you.

I'm not going to beat shit out of anyone. He wants answers, he can either quit being all cagey like some high school girl discussing prom dresses, or post/PM what the goal is so we can give proper assistance.

[wnaplay1647545503]

Dude...You need to be a bit more specific if you want help. What are you wanting to do with What exactly. Yes motors can be swapped, but if there is other components, you need to consider voltage of these as well as a lot of 3PH equipment has both single and 3PH components installed.

 

Just spit it out....Damn.

You want help but your making us almost beat the damn info out of you.

Spit what out? I am buying a commercial oven, as stated I have access to single phase and 3 phase. Not sure which one to get. Not sure what info your looking for. I am pretty sure the answer was already given, for heavy use the 3 phase would be more cost effective to operate.

[Xyster101]

When you use a higher voltage you need less amps. A 2000 watt electric heater draws 16.6 amps at standard 120 volt house current. That same heater draws only 9 amps at 220 volts.

3 phase uses more voltage (480) in the form of 3 power feeds, thus less amps are needed. A motor has windings inside to create magnetic fields. With 3 phase you get 3 times more magnetic fields as you can have 3 sets of windings. That way you can get more power out of a smaller electric motor. Typically a house motor is limited to around 2 hp for machinery. 3 phase machinery can go much higher hp.

Higher voltage is also more dangerous to the typical Joe Smith. If you want to use it in your home, you will need to build a converter to change single into 3 phase. Those converters "cheat" and don't really make 100% pure 3 phase power.

Industrial equipment is cheaper in 3 phase, especially used things as home owners can't use it. Companies typically buy things new, so the used market is a buyers market. You can sometimes change a motor out from 3 to single, BUT you can't take a 7hp 3 phase and put a 2 hp single motor in.

[MattKatz]

Spit what out? I am buying a commercial oven, as stated I have access to single phase and 3 phase. Not sure which one to get. Not sure what info your looking for. I am pretty sure the answer was already given, for heavy use the 3 phase would be more cost effective to operate.

 

Its only more cost efficient if you have three Phase available....If not, and this is an Electric oven, its now not as easy to convert, nor would I do it on something like this. I assume youre looking at a 230 3PH Oven, as I am sure 480 isnt available unless you are in a commercial area. If you dont have 3PH where you are, finding a comparable single phase unit will be your better bet IMO.

 

And Yes, I actually know what Im talking about, I deal/work with 3PH daily.

[mmrmnhrm]

I am buying a commercial oven

*THIS* is the piece of info we were all after. Knowing this, we can say as long as the prices aren't totally out of line with each other (3ph version costs 10x the 1ph or something stupid like that), and the voltages match up (208V socket and 208V oven, or there's space and money for a transformer), go ahead and get the 3ph unit. Others have pointed out the efficiency gains to be had on a higher voltage unit, and being a purely resistive load (not a motor), depending on the design it may even continue working should one of the phase coils fail

[Mensan]

Its only more cost efficient if you have three Phase available....If not, and this is an Electric oven, its now not as easy to convert, nor would I do it on something like this. I assume youre looking at a 230 3PH Oven, as I am sure 480 isnt available unless you are in a commercial area. If you dont have 3PH where you are, finding a comparable single phase unit will be your better bet IMO.

 

And Yes, I actually know what Im talking about, I deal/work with 3PH daily.

 

If that's true, where the fuck are you working on 230V 3ph?

[mmrmnhrm]

If that's true, where the fuck are you working on 230V 3ph?

Meh, I'm not going to pounce on that. HVAC gear is regularly stamped 460V even though it's damned near impossible to find that in the US.

[Awfulcanawful]

Can someone explain the delta vs. wye config? Either in physics or practical use? I am just starting to mess with this three phase thing and want to know the difference. Does the voltage make a diff? We deal in 208/240/480can I tell from that? and would I be able to differentiate the two with a meter at the wall plug?

[mmrmnhrm]

Can someone explain the delta vs. wye config? Either in physics or practical use? I am just starting to mess with this three phase thing and want to know the difference. Does the voltage make a diff? We deal in 208/240/480can I tell from that? and would I be able to differentiate the two with a meter at the wall plug?

Delta vs. Wye is basically how the wires inside the motor or transformer are wound. The physics behind them are the same... wire loops create a magnetic field which is then used to create motion (a motor), or a flux inside some material which is then used to create a new voltage inside a second set of wire loops (transformer). Where they differ is how the loops are connected in relation to each other, at the ends or in the middle.

 

With regards to voltages, what you can get from the different systems is different (you can't get 277V from a 480V delta without transformers, but it's right in front of your face in a wye, likewise you can get 240V from a delta, but not a wye). So if you're able to measure what's inside the panel, you can usually figure out what you have to work with, but if all you have are sockets, then there's no way to tell whether you have 120/208/240 high leg delta, 120/208 wye, or 120/240 split.

[MattKatz]

If that's true, where the fuck are you working on 230V 3ph?

 

208/230 3PH.....All over Dayton man.....Id say half the equipment I deal with daily is 208/230.....Its VERY COMMON.

And as far as equipment stamped 460V....correct, its how its rated even though its technically on 480V line Voltage. However, the actual voltage reading could be anywhere from 465-495 and still be at an acceptable Voltage level to use.

 

Since I take it you are implying I dont have a clue...Ill be happy to mail you a copy of my "Clue"