Woodworking Talk banner
1 - 20 of 37 Posts

·
Registered
Joined
·
181 Posts
Discussion Starter · #1 ·
I've read about options for powering three-phase equipment.

The plan for our next house (2-3 years away from the start of construction) is to have a standby home generator large enough to power the whole house.

From a quick look, I see that I could get a three-phase model. So my thought is that maybe I could use one to power tools in addition to being a back up for the "regular" household service.

I know nothing about them, this idea just occurred to me. I thought I get ideas here before I starting looking further into it. I realize if it is possible to get one standby unit that would power the 110/220 single-phase when needed and also run three-phase part of a shop, it will cost more than a standby that just supplies the house current.

I appreciate any info on the idea, especially about it being possible to do with a single standby unit.
 

·
where's my table saw?
Joined
·
31,291 Posts
I have a single phase 15,000 watt, "dual voltage", 120/240 standby generator that runs on "dual fuel" either propane or if rejetted natural gas.
I wasn't aware off a "dual phase" stand by generator, so I did a search:
I found this 3 phase only at 400 AMPs for only $36,500 !!!!
Cheaper here:

I have a buddy who runs all his old cast iron machines on 3 phase, and he uses a rotary inverter made from a large single phase motor.
Don't ask me how it works, but when he first fires up the shop,go goes over to the motor and :kick starts" it spin it and that's it.
You Tube probably has a "How TO" on that.

It's up to you how you choose to do this, BUT I only have single phase and run two 5 HP compressors with no issues. I do NOT run the stand by to power machines in the shop, but I probably could if absolutely necessary? My hot water is electric as is the clothes dryer, and well pump. My furnaces are propane so I'm stingy with how much I can use to power the stand by. If I run out of propane I also have no heat in the winter. If you are on Natural Gas, then that's much better.
For the few dollars saved to go 3 phase on powering woodworking machines, I don't see it being worth it. It is really "Industrial" electrical supply, not Residential.
 

·
Administrator
David - Machinist in wood
Joined
·
6,076 Posts
From a quick look, I see that I could get a three-phase model.
At your new location, is three phase available at a reasonable cost from your power company? If not then I wouldn't get any three phase equipment.
 

·
where's my table saw?
Joined
·
31,291 Posts
At your new location, is three phase available at a reasonable cost from your power company? If not then I wouldn't get any three phase equipment.
My experience in living both in cities and rural areas and towns, is that 3 phase is supplied to industrial areas, typically clustered together like a subdivision or in main trunk lines.
It is not run in residential neighborhoods, unless they are converted older buildings, like lofts or warehouses.
Where I live, it's all rural subs and farmland. There farms can get 3 phase, the subs do not.
I think it's there on the poles, just not coming down from the residential type transformers, but I could be wrong about that.
@Rick Christopherson would know.

See this paragraph:
3. Rotary Phase Converter:
 

·
Registered
Joined
·
181 Posts
Discussion Starter · #5 ·
At your new location, is three phase available at a reasonable cost from your power company? If not then I wouldn't get any three phase equipment.
I don't have a price from the power company. "Reasonable" is hard for me to define at this point in time. I don't need three-phase equipment, it's a matter of how much I want it. In addition to wood, there will be an automotive and metal shop. My friend has some three-phase equipment that we would like to put in there. Again, we don't need to have it, we need to decide how much we want to have it.

From things I've heard about dealing with power companies and three-phase, the price can vary based almost on who you talk to. The house we are in now has overhead wires from the utility pole to the house. At one point the power company would have buried them for $400 which was the cost of the material. A few months later when we decided to do it they wanted over $2,500. The guy who came out to talk to me said the new boss decided they should make money on it.
 

·
Registered
Joined
·
28,404 Posts
I've read about options for powering three-phase equipment.

The plan for our next house (2-3 years away from the start of construction) is to have a standby home generator large enough to power the whole house.

From a quick look, I see that I could get a three-phase model. So my thought is that maybe I could use one to power tools in addition to being a back up for the "regular" household service.

I know nothing about them, this idea just occurred to me. I thought I get ideas here before I starting looking further into it. I realize if it is possible to get one standby unit that would power the 110/220 single-phase when needed and also run three-phase part of a shop, it will cost more than a standby that just supplies the house current.

I appreciate any info on the idea, especially about it being possible to do with a single standby unit.
Powering three phase from a generator wouldn't be any different than from the electric service unless you are talking about 440 three phase. You would have to get a larger generator which would provide the amperage comporable to what your electric service is, if you plan to power the house and the shop at the same time. If you could get by with shutting some things down when on the generator you could use less of one. It's just a matter of your needs.
 

·
Registered
Joined
·
181 Posts
Discussion Starter · #7 ·
See this paragraph:
3. Rotary Phase Converter:
"For air compressors, considered one of the toughest starting loads, the recommended factor is at least 2. In my case, that meant a 10HP rotary converter, which is not even a little bit cheap."

That would apply if I want to use one of the compressors we have. Sure we can change the motor to a single-phase, but I don't want to spend as much modifying equipment as we might spend to get three-phase.

I've read about some options, like described in the article woodnthings referenced. They never mention a generator, but maybe that's because the cost to buy one just to have three-phase power might be too high. Since my wife and I will be buying a generator anyway, the extra cost to add three-phase (if that's possible) might be acceptable.
 

·
Registered
Joined
·
181 Posts
Discussion Starter · #8 ·
Powering three phase from a generator wouldn't be any different than from the electric service unless you are talking about 440 three phase. You would have to get a larger generator which would provide the amperage comporable to what your electric service is, if you plan to power the house and the shop at the same time. If you could get by with shutting some things down when on the generator you could use less of one. It's just a matter of your needs.
Steve, I understand what you are saying about amperage. What I'm trying to figure out is if one generator can supply both 120/240v single phase and three-phase (not 440). I just thought of the possibility of doing that but haven't had time to look at generators yet to see if it is possible and how much it will cost for a generator like that - if it exits - vs a 120/240 single phase that we'd be buying otherwise to power the house.

Next week I think I'll carve out some time to talk to Generac or another manufacturer and spend some time seeing what is available beyond just a 120/240 standby home generator.
 

·
where's my table saw?
Joined
·
31,291 Posts
Like I said, the choice is yours, but in my opinion, you can run your 5 HP on a single phase if the power goes out.
If you always need to run a generator to get your 3 phase, that will disturb any close by neighbors and possibly your own peace and quiet.
I know mine is quite noisy when it runs and it resonates the whole house, but not so much that it vibrates, you just hear it running.
I doubt if you will be saving any money going down this road, but I could be wrong.
 

·
Registered
Joined
·
28,404 Posts
Steve, I understand what you are saying about amperage. What I'm trying to figure out is if one generator can supply both 120/240v single phase and three-phase (not 440). I just thought of the possibility of doing that but haven't had time to look at generators yet to see if it is possible and how much it will cost for a generator like that - if it exits - vs a 120/240 single phase that we'd be buying otherwise to power the house.

Next week I think I'll carve out some time to talk to Generac or another manufacturer and spend some time seeing what is available beyond just a 120/240 standby home generator.
The generator develops the 220 single phase. You use a phase converter to make three phase from single phase 220. I believe most people like a VFD for this however you have to have one for each different three phase machine you have. Myself, I have four machines on a rotary phase converter and I can run one or all four on the same converter. This type uses a three phase motor to spread the power out to the third leg. It's because if you could hook up a three phase motor to 220v and it would run if you had a second single phase motor to get it turning. Once the three phase motor was turning you could then hook up a three phase machine on the same circuit and it would start and run. Now, it wouldn't run real great but it would function. The circuit board on the rotary phase converter has capacitors to get the motor on the phase converter turning. Then because of the power drop on the third leg it has capacitors in it which bump up the third leg to 220v. By doing this it comes close to actual three phase.
 

·
Administrator
David - Machinist in wood
Joined
·
6,076 Posts
"Reasonable" is hard for me to define at this point in time.
About 25 years ago I lived in a subdivision three doors down from my parents. When I was a kid and we were building the house my parents were in my Dad specified a 5-ton 3-phase air conditioner so that when the AC came on the TV picture wouldn't shrink down for a couple of seconds (as they did in that era); it was important enough to him that he was willing to have two services. But it was in the early 60's in a new upscale subdivision and the electric company didn't charge any extra to do a 3-phase drop for one house. It was/is the only house in the entire 1,000+ home subdivision to have 3-phase.

Since I was only three doors down, and had some 3-phase equipment that I had brought home from my woodworking business, I asked the power company to run 3-phase to our house. At first they told me it wasn't in the neighborhood until I proved to them that it was on a pole only 200' away. So they gave me a quote - $5,000. In other words, they didn't want to do it even though it turned out the lines were already at my pole because years earlier, in the early 60's, they thought others might also want 3-phase. So all they needed to do is run it to the house and put in another meter but they wouldn't yield from the quote and suggested that if I took very long to decide the price would go up.

When my parents passed away we sold the house and the new owners put in a single phase AC unit. The transformer is still in place on the pole and the separate meter is still on the side of the house but neither has been used in years.
 

·
That Guy
Joined
·
578 Posts
What I'm trying to figure out is if one generator can supply both 120/240v single phase and three-phase (not 440).
No, The windings of the generator head determine this and you can't have both.

You may be able to buy a three phase genny and then use a transformer to convert the 3 phase to 240VAC single phase. A more experience electrician than me can chime in on the feasibility of that. I think it would be terribly inefficient.
 

·
Registered
Retired engineer
Joined
·
355 Posts
The chief advantage of 3-phase is it delivers constant torque because the algebraic sum of the 3 voltages at any given time is constant (or nearly so). The chief disadvantage is cost.
Will you get constant torque if you use a rotary converter? It's doubtful, because the original power going into the converter is 1-phase.
3-phase is rarely used on motors less than 5HP. So unless you anticipate buying something with a 5+HP motor, or you already own one, then maybe you don't need 3-phase.
One way to tell if you have 3-phase in the neighborhood is to look at the top cross tree on a power pole. 3 insulated wires = 3-phase, 2 = single phase. There is usually an uninsulated wire as well. This wire does not count. It is there as a neutral connection and to absorb lightning strikes. The other way is to call your utility. If you can't get 3-phase there really isn't much point in buying a 3-phase genny.
There are delta connections (3 wire) and wye connections (3 wire + neutral). Utilities generally run delta connections because it saves on wire, then convert to wye because they can get 3 single phase line-to-neutral connections for the suburbs.
If you want to go down this path, hire a good industrial electrician. Your normal household electrician will tell you that if he is any good. If he tells you he can do it, ask him how many houses he has wired with 3-phase. If he says more than 5 he's a liar; people just don't have 3-phase in homes. Around here, I have seen one house with 3-phase and it was built in the '50s. Utilities run 3-phase all over the place, but rarely into suburbs. Any large building (e.g. local Frys/Kroger) will use 3-phase for HVAC) .
(based on 45+ year old memories from my power distro class which I mostly slept through as an engineering student. Might be 75% correct, but a C is a passing grade, right?)
 

·
Registered
mechanical engineering
Joined
·
251 Posts
Generators are based on the utilization of the application.

If your primary load is single phase only do not apply it to a 3-phase generator.

here is why you not apply single-phase loads 3-phase generator.

think about the windings in a circle A,B,C your load is only is on A and B. C has no load.

it creates excessive vibration during the rotation A,b and C no load. this creates what is referred to as excessive winding wear. the maintenance cost of the generator with more than quadruple due to inefficiency and excessive vibration. my group owns a lot generators about 50 of them. the small ones 5kw air-cooled al the way through to one-megawatt water cooled. example the one megawatt generator cost us over $5,000 a year in maintenance.

like with any mechanical system they must be run regularly Under full load.

also different fuel types different maintenance costs. natural gas versus propane versus gasoline versus diesel fuel. the cheapest for us to maintain is natural gas.



here is a link or using natural gas. How Much Does It Cost To Run A Generator On Natural Gas? (Calculator)

the cost per hour is much higher than most people would think.
 

·
Registered
Joined
·
13,544 Posts
At your new location, is three phase available at a reasonable cost from your power company? If not then I wouldn't get any three phase equipment.
Totally agree. The normal hobby woodworker has no need for 3 phase.

I have had a standard whole house standby generator for 17 years. it is used ONLY as a standby. It really has been needed very little in that time.

I am beginning to feel a little uncomfortable about the age. Am having a thought that maybe it is time to update. I just want to be sure that if we lose power for several days during a hurricane that it will continue running.

george
 

·
where's my table saw?
Joined
·
31,291 Posts
Totally agree. The normal hobby woodworker has no need for 3 phase.

I have had a standard whole house standby generator for 17 years. it is used ONLY as a standby. It really has been needed very little in that time.

I am beginning to feel a little uncomfortable about the age. Am having a thought that maybe it is time to update. I just want to be sure that if we lose power for several days during a hurricane that it will continue running.

george
They don't "wear out" especially with such infrequent use. Drain the oil every three years. Then I would change out the battery if it's more than 3 years old, as they are the first to go. Then make sure your fuel/gas has an additive. I used to use Sta-bil, the red stuff, But on some one's advice, I switched to Startron, the blue stuff. I haven't had a gummed up carb since. I treat every gallon of fuel I keep stored with it whether it's for 2 cycle or 4 cycle, the log splitter, 5 chainsaws, edge trimmer, and trucks that don't get driven much.
 

·
Registered
Joined
·
181 Posts
Discussion Starter · #17 ·
So they gave me a quote - $5,000. In other words, they didn't want to do it even though it turned out the lines were already at my pole
Not too different from us with getting the overhead wires buried. We didn't do it, wasn't worth it for $2,500.

I've heard numerous stories about people trying to get three-phase power. It seems each power company is different and even within one company there is no standard for whether they will do it or what it would cost. We had something similar with AT&T. The house next to us has them for internet and TV (wired, not a dish). Much better price than we have with our cable company. So we called AT&T. They said it was not available for our address, we'd have to get a dish. I asked how that could be, given our neighbor has it. They told me we were too far from the node (we have 1/4 acre lots, houses are pretty close together). I found out later that the house on the other side of us also had AT&T wired. Apparently they leave existing customers but want new ones to go with their dish system.
 

·
Administrator
David - Machinist in wood
Joined
·
6,076 Posts

·
Registered
Joined
·
13,544 Posts
They don't "wear out" especially with such infrequent use. Drain the oil every three years. Then I would change out the battery if it's more than 3 years old, as they are the first to go. Then make sure your fuel/gas has an additive. I used to use Sta-bil, the red stuff, But on some one's advice, I switched to Startron, the blue stuff. I haven't had a gummed up carb since. I treat every gallon of fuel I keep stored with it whether it's for 2 cycle or 4 cycle, the log splitter, 5 chainsaws, edge trimmer, and trucks that don't get driven much.
I put on new filter and change the Mobile 1 every year. No way/need to add "additive" to natural gas. Sta-bil is good long stabilizer. I used to use it on my boat to keep the gasoline fresh over winter. Still use it on any gas I buy for accessories.
I know a generator should not wear out with infrequent use, but just my old age nerves I guess. Or maybe it is just wanting a new system.

George
 

·
That Guy
Joined
·
578 Posts
There is one other option... You can buy a VFD, a Variable Frequency Drive, that will take in 240VAC and output 3 phase to run a motor. It's a box full of semiconductors and a microprocessor. It's not cheap but if you are looking at a killer deal on some used piece of shop equipment you always wanted it may be the missing link that makes it work in your shop.

Like this for example:

 
1 - 20 of 37 Posts
Top