Converting three phase to 220V

[Jason M]

Okay, I have heard that it is a Royal PITA and that it is simple.

Anyone have a good link or can make the "black box" that will allow me to run a 3 phase Drill press on single phase 220 (if that is even the right term..)

[CJ]

It is called a phase generator.
First shop I worked at had one on his table saw.
How many horse motor is it?
It may be cheaper to buy a single phase motor.

[big97redtj]

Go to a machine and equipment auction. When we bought our mill, a phase generator went for a whopping $50. It was a nice unit that didn't see very much use. Electrical components never seem to hold thier value.

[PTSchram]

There are lots of different ways to do this, but the cheapest and easiest (without auction deals) is to buy a new motor.

[Eric]

The cheapest and easiest way is not to replace the motor. That is too expensive and too much money.

The cheapest way is to build a static phase converter. A potential relay, motor start cap, a run cap and some wire and you just made a psuedo 3 phase converter. This way you loose about 33% of the rated HP of your motor.

The next way to do it is to find a bigger 3 phase motor "idler motor" and make rotary phase converter where you use a static converter to start the idler motor and then once the motor is started, you remove the static converter out of the circuit and use the output of the idler motor to run the drill press motor. These are noisy and consume more energy.

I prefer the easiest method and use a VFD (Variable Frequency Drive). These have become so cheap in the past few years and they are becoming more and more popular. Basically it takes a single phase input and creates a 3 phase output. They range from super simple to super complex with all kinds of features. I use one on my Bridgeport Mill. You can change speeds by adjusting the output frequency instead of changing pulleys all the time (within reason).

Replacing the motor is normally expensive since a single phase motor is generally more expensive than a 3 phase motor. You also have to find the correct motor with the right shaft diameter and mounting pattern.

There are lots of ways to do it and pros and cons of each setup, but in my experience the best way is to go with a VFD.

Give me more specs on the drill press and I can help you out......(electrical engineer)

[sewerzuk]

Just a quick explanation of 220v and 220v 3 phase; regular 220v is actually just two phases of 110v 180 degrees out of phase (so that you get 220v when compared to each other). Almost every house, shop, etc. in america has this in their power panel. There is no way to electrically convert this 220v into 3 phase; it requires 3 phases 120 degrees out of phase. To get it, you either need to pay the power company a huge amount of $$ to add another transformer on your power pole (if you don't have one already) and run new lines to your panel, or buy a phase generator (as other people mentioned). The phase generator is simply a 220v motor mechanically connected to a 3 phase generator. You plug in the motor to your existing 220v jack and get 3 phase from the generator. We had them all over our ships (so check for military surplus ones), but they're farily common in industrial shops as well so keep your eyes open on ebay and for any local shops that are going out of business.
Hope this helps!

[camo]

i bought my static phase converter from a company i found on ebay. http://cgi.ebay.com/ws/eBayISAPI.dll...824321008&rd=1 i called them up and told them what i was running and they send me one out and i had it the next day. my unit cost about $80. I use it to run my bridgeport mill, doall bandsaw, burr king grinder, dril press. it is a simple little device that comes with wiring instructions and is a simple install. been using mine for years with no proplems.

[Jason M]

Right on, thanks..


Basically I am getting a 1 hp, 3 phase drill press

[camo]

then a $80 static converter will most certainly do the trick

[Eric]

Originally Posted by Jason M

Right on, thanks..


Basically I am getting a 1 hp, 3 phase drill press

When using a static converter, you are only going to see about 2/3 hp from that motor.

[CP8071]

Depending on the amount of work you want to do yourself you can do what the others have mentioned. The static converters are simple and cheap, but you have to remember it will de-rate the motor. Check eBay for VFDs and be sure to look at models that will accept 230 single phase input. Here's a company that makes some cool small VFD units. 230V Single Phase input and up to 1HP for $159. You can add remote start/stop and reverse switches and even a remote potentiometer for speed adjustments ... pretty cool.

Automation Direct VFDs

CP

[LandCroozer]

If 3 phase is such a headache, why is it used at all?
Are they more efficient in an industrial setting where 3 phase is already piped in? Are the motors actually cheaper to produce? Run quieter, last longer?

-tom

[frankenfab]

There are a lot of misconceptions out there. Here is the truth:

110, 115 or 120 and 220, 230, and 240 are single phase. The exact voltage depends on your local power company.

At my house, Utah power supplies 240 volt single phase. It is supplied by a center tap transformer. There is an L1, an L2, and a Neutral. If you place a scope or a meter from L1 to L2, it will measure 240 volts. If you place a meter from L1 or L2 to Neutral, it will measure 120 volts. A meter is comparing the potential difference between the two leads. How voltages appear depends on where you stand and how you look, so to speak. If you hook a 2 channel scope to L1 and L2 and reference each channel to neutral, it will appear that there are 2 phases, with a 180 degree phase angle difference between L1 and L2. That is because you are referencing to a center tapped transformer supplying the neutral. It is truly only a single phase of 240 volts.

Common 3 phase supply is 120/208 or 277/480. Each phase has a 120 degree phase angle difference from the other.

For an alternating current motor to turn, there has to be a rotating magnetic field. With single phase power, generally a capacitor is used to cause a phase shift. This esssentially creates a second phase. This second phase is used to create the rotating magnetic field. Three phase power does not need a capacitor to create the rotating field. Each phase already has a 120 degree difference. It is much more efficient and is the reason industrial buildings are supplied 3 phase.

If you look on power poles, you will almost always see sets of 3. Even in residential areas, 3 phase is present. They are just dropping single phase to the customers though. The voltage on the poles is very high. They are stepping it down to your house voltage. Usually one phase will supply a few houses, the second a few more, and the third a few more. They try to balance all the houses in the area between the three phases. It is possible to install a 3 phase transformer, but they'll charge you for it (if they are even willing to do it at all).

The other options are rotory and static phase convertors or a variable frequency drive. Google search for information on those. There is a lot of information on the web.

[sewerzuk]

Originally Posted by LandCroozer

If 3 phase is such a headache, why is it used at all?
Are they more efficient in an industrial setting where 3 phase is already piped in? Are the motors actually cheaper to produce? Run quieter, last longer?

-tom

Two nearly identical motors, one on 240v single phase and the other on 3 phase: the 3 phase one will take less real power, meaning less heat produced. Less heat = more efficient, more HP, longer life, etc. Many larger loads require the use of 3 phase, or the motors would have to be HUGE to handle the current necessary to run on single phase.

[sewerzuk]

Originally Posted by frankenfab

110, 115 or 120 and 220, 230, and 240 are single phase. The exact voltage depends on your local power company.

Yup...if it says 208, then it's 3 phase. If it says any of the above numbers, then it's single.

Originally Posted by frankenfab

At my house, Utah power supplies 240 volt single phase. It is supplied by a center tap transformer. There is an L1, an L2, and a Neutral. If you place a scope or a meter from L1 to L2, it will measure 240 volts. If you place a meter from L1 or L2 to Neutral, it will measure 120 volts. A meter is comparing the potential difference between the two leads. How voltages appear depends on where you stand and how you look, so to speak. If you hook a 2 channel scope to L1 and L2 and reference each channel to neutral, it will appear that there are 2 phases, with a 180 degree phase angle difference between L1 and L2. That is because you are referencing to a center tapped transformer supplying the neutral. It is truly only a single phase of 240 volts.

Since you disclaimed your paragraph with "How voltages appear depends on where you stand and how you look, so to speak." I'll agree with everything. But, it isn't just the neutral that you compare each hot line to and get a single phase of 120, you can compare it to earth ground as well and get a single phase of 120 (neutral is tied to a grounding rod and/or cold water piping in the main panel usually)...I was taught and always understood that this means that there are 2 separate phases of 120. You ONLY get 240v if you compare them to each other (because they are 180 degrees out of phase). If you look in most breaker boxes in a house, you have 2 separate phases of 120v coming in; all of the breakers on one side are supplied by one phase, the other side are supplied by the other phase. If you want 240v from that panel, you install a breaker that has 2 poles (taps off of both sides at the same time).
frankenfab, I'm not disagreeing with what you wrote...obviously you know what you're talking about. I'm just trying to make things clear for everybody.
I've always heard 240v referred to as single phase, I'm just saying that it really isn't. A single phase of 240v would be a hot and a neutral, with the hot having a sine wave with 240v RMS.
I hope I didn't sound like a jackass...it's just that I wouldn't understand it unless it was explained to me like I just wrote it...

[frankenfab]

Originally Posted by sewerzuk

Yup...if it says 208, then it's 3 phase. If it says any of the above numbers, then it's single.



Since you disclaimed your paragraph with "How voltages appear depends on where you stand and how you look, so to speak." I'll agree with everything. But, it isn't just the neutral that you compare each hot line to and get a single phase of 120, you can compare it to earth ground as well and get a single phase of 120 (neutral is tied to a grounding rod and/or cold water piping in the main panel usually)...I was taught and always understood that this means that there are 2 separate phases of 120. You ONLY get 240v if you compare them to each other (because they are 180 degrees out of phase). If you look in most breaker boxes in a house, you have 2 separate phases of 120v coming in; all of the breakers on one side are supplied by one phase, the other side are supplied by the other phase. If you want 240v from that panel, you install a breaker that has 2 poles (taps off of both sides at the same time).
frankenfab, I'm not disagreeing with what you wrote...obviously you know what you're talking about. I'm just trying to make things clear for everybody.
I've always heard 240v referred to as single phase, I'm just saying that it really isn't. A single phase of 240v would be a hot and a neutral, with the hot having a sine wave with 240v RMS.
I hope I didn't sound like a jackass...it's just that I wouldn't understand it unless it was explained to me like I just wrote it...

There is only a single phase of 240. It appears to be 2 phases due to the center tap, but is not. Yes there is a ground, and it is tied to Neutral at the service entrance, and thus, the Neutral is called the grounded conductor. The ground is not meant to carry current, except to clear a fault (trip a breaker with a malfunction). I didn't want to over complicate.

Here is a simulation I designed:



The signal generator on the left represents the power company high voltage (a single phase). Then a pole mount, center tap transformer delivering 240 volt, single phase. The two lamps represent 120 volt loads on L1 and L2 (Neutral return). The meter on the right shows the 240 single phase across L1 and L2. A 240 volt device would not use the Neutral at all. The bottom image is showing what L1 and L2 look like referenced to Neutral.

[camo]

thanks for the tech guys

[PTSchram]

Man am I glad I have three phase right at the panel!!!

Now if I can only get my big lathe moved to the shop.

[sewerzuk]

Frankenfab, did you do that with EWB? I have a copy somewhere but haven't installed it...looks like it might be fun.

I understand AND AGREE with what you're saying, just that in every class I've taken ('m not a EE, but I've taken 2 years of electronics classes) refers to the 2 waves on your scope as 2 separate phases (even though they were generated from a single phase...99% of the time I've referenced my oscope to ground or neutral...a floating fround was VERY uncommon for me). Just a difference in terminology, I guess. I'm arguing microelectronic stuff and this topic was about commercial power...2 different worlds.
I guess I can let it go :P

[Slowzuki]

sewer zuk, 220 is single phase, we were told there have been some 2 phase systems in use in the past (europe I believe) but have been failures.

Another benifit of 3 phase is the motors run much smoother, there is less variation in armature torque during rotation. This is important in larger machines as it can reduced the required sizes of shafts.

[PTSchram]

Originally Posted by Slowzuki

sewer zuk, 220 is single phase, we were told there have been some 2 phase systems in use in the past (europe I believe) but have been failures.

Another benifit of 3 phase is the motors run much smoother, there is less variation in armature torque during rotation. This is important in larger machines as it can reduced the required sizes of shafts.

I think many refer to 220 as 2 phase as we have the ability to separate it into two separate "phases" of 110 (each buss of the breaker box).

As for benefits, the main benefit is that with three phase, each winding in a motor is only handling one-third of the load and as a result, the windings can be smaller gauge (less expensive investment), and greater efficiency as each winding is only heating 1/3 of single phase (or, more accurately, only dissipating 1/3 as much power for each winding-but, then Newton becomes involved and the savigns are less than the 1/3-damned entropic losses).

(former electric utility employee, former magnet wire employee)

PT

[87GMCJimmy]

Here's a link on building your own rotary phase converter. I used the design for the self starting unit and it works fine. I picked up a motor for free and about 20 bucks in parts had it working. I use it to power a 1hp 3phase industrial drill press I got off ebay for 60 bucks.

http://www.metalwebnews.com/howto/ph-conv/ph-conv.html


Mike

Ps. Thanks for the detailed info on how 110/220 works!

[sewerzuk]

Originally Posted by Slowzuki

sewer zuk, 220 is single phase

Thanks for the tech

I'm letting my argument go...I'll call 240v single phase and just think of it as 2 phases of 120v in my head, where all my make believe friends agree with me