[OP]
Member
I'm redoing the wiring in my new studio, which has tons of 3phase, but little 110 or 220 easily accessible. I'm going to split up several of the three phase plugs, and am wonder whether I should leave myself a 220 circuit and convert my Dewalt 746 TS? Am I going to get a noticeable power or performance increase? Is it work the time/$ when I could have one more 110 circuit. Any thoughts?
Thanks
Member
when you say you have lots of 3 phase what do you mean?at what voltage? is the saw 3 phase or single phase.
Or you you mean you have 3 wire 240 single phase house hold power?
jack
English machines
Member
Assuming you are at 110v single phase, and want to know about going to 240v single phase, no it won't give you more power. What it will do, is lower your amp draw for that particular machine in half, and allow you to run lighter wire to the outlet. As a rule, you always try to run your equipment at highest possible voltage when it is an option. Machines run better and cooler, thus lasting longer.
[OP]
Member
I've got lots of receptacles of three phase at various combinations of voltages and Amp circuits. I'm thinking about converting one to 220 single phase, in addition to some 110 single phase.Originally Posted by jack forsberg
Saw is 120/240 single phase, right now set up as 120.
Member
Alex
how much experience do you have with 3 phase power? Your not making sense is why i ask . If you have 3 phase what is the primarily voltage entering the building?
There are ways to get single phase power from 3 phase . Do you have transformers and what are they.
How are you running the saw now?
jack
English machines
Member
You probably can't get 240v from your 3phase, but only 208v. Your saw might work on 208v, but not as well as it does on 120v.
Even if you do have 240v, there is no good reason to use it for your saw. It is only 15a and will work just fine on a 20a line that doesn't have other stuff on it.
Member
If you really have native 3 phase in the studio I'd be more inclined to shop for a good 3 phase saw than get into any backwards conversions.
Member
>>>> As a rule, you always try to run your equipment at highest possible voltage when it is an option. Machines run better and cooler, thus lasting longer.
No, that's not a rule. All convertible 120/240 motors always run on 120 volts internally. There are two coils each running 120 volts and using 1/2 the 120 volt amperage (The coils act as a resistance and split the amperage). All you do when you re-wire the motor to run on 240 is change the wiring connecting of the coils from parallel to series. When wired for 240 volt operation, one 120 volt leg and its associated amperage is routed to each individual coil rather than a single 120 volt line providing 120 volts to both coils. The same voltage and amperage runs through the individual coils no matter how it it wired. It is amperage that creates heat, and because the amperage in each coil is the same for both wiring configurations, there is no difference in the heat produced by either wiring configuration. The motor is perfectly happy with either voltage and doesn't even know you made the change.
Howie.........
Member
Howie, not being an electrical engineer, I am having a little trouble following what you said. If the motor converts 240 to 120, then it is in effect a transformer?? And if it is amperage that creates heat, how is it that a motor wired at 240v and supplied with 1/2 the amperage of the 120v motor doesn't run cooler? I'm not connecting the dots? I'm sure you have much more experience than I do, I'm only a woodworker in real life, but .... So in essence if you supply 240v to a convertible motor, it transforms it to two legs of 120 and turns it into a heater of sorts?, and in doing so acts like a boost transformer?
Seems like that defeats the purpose of higher voltage motors.
Member
Agreed! Three phase is pretty sweet and opens up a lot of equipment options.
Member
My understanding is the only reason to run dual voltage tools at the higher voltage is to be able to run smaller circuits and gauge wire as the motor is pulling less amps. Other than that they should run the same way.
As far as pulling 110 or 220 single phase from a 3 phase outlet, I wouldn't try it unless you have a really good handle on electricity. I know there are at least 2 types of 3 phase power and the one I have has different voltages in different wires. There's also no neutral wire in 3 phase which would make a 110 single phase outlet tricky, I'm not sure multiple 110 outlets from a single line would even be possible? I'm not saying it can't be done, just that if it can it's probably best handled by an electrician
good luck,
JeffD
Member
Peter,
Howard's explanation is exactly correct. Unfortunately, to understand it, you will have to understand a little about the nature of AC power and phase angles. If you measure the voltage between one hot leg of a 240V plug and neutral, you will read 120V nominal. The same is true if you measure the voltage between the other hot leg and neutral. The 240V is measured between one hot leg and the other because they are 180 degrees out of phase. With 3-phase power, the story gets even more complicated because the voltages of the three legs are 120 degrees out of phase with each other. Don't worry if that doesn't make any sense. It is probably not worth the effort to learn what it means. Suffice it to say that the current running through the two coils of a single phase motor added together is the same whether they are connected in parallel (120V) or series (240V).
I need to add that there is more to consider than the current in the windings of the motor. There is also the amount of current in the wires feeding your breaker box. In my case, the wires going to my shop are just barely adequate. A motor running on 240V will require half the current of a motor running on 120V. Therefore, I run all the equipment I can on 240V to avoid the voltage drop in the feed wires.
Just my experience but, in a word, no. There are lots of minutia that folks cling to to justify running higher voltage but, for a tool that runs correctly on 110v, the user experience at 220v is the same. Reports of moving from a poorly provisioned, shared, overworked 110v circuit to a dedicated, properly provisioned 220v circuit perpetuate the stories. Minutia aside, watts is watts.
"A hen is only an egg's way of making another egg".
– Samuel Butler
Member
Art has given the best explanation along with Howie. The only reason to run 220 is to lessen the voltage drop on the wiring or to be able to use lighter wiring than running 120v.
Member
Well, the other reason to run higher voltage- at least where I am, is that as a business, I pay commercial rate which is higher. Also, along with a higher rate for your power, we are on a demand meter which bases your rate on your amp draw!
The more amps you draw the higher your rate for what you use. So I run high voltage everywhere I can.
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