Phases question single<>three

3 ph motors cost less to make, so they sell them cheaper. I agree with you; 3 ph is better in all respects.

-- David, Southern Indiana, http://www.freedhardwoods.com

Do you have 3 phase power in your shop?

I think you are asking PurpLev, but this is what I have.

http://www.americanrotary.com/20-HP-rotary-phase-converters.html

-- David, Southern Indiana, http://www.freedhardwoods.com

I was asking PurpLev. Sorry I didn’t make that clear. But you made my intended point, which is that though a 3 phase motor may be cheaper and better, the rotary phase converter needed for a typical home shop installation will cost way more than any savings on the 3 phase motor.

It may seem more expensive to go the 3 phase route. But, it makes sense if one has the opportunity to buy high quality used machines that have large 3 phase motors. They cost of changing the 3 phase motors to single phase would be much more expensive. I have both 3 phase and single phase. 110v and 220v

-- Oldworld, Fair Oaks, Ca

PurpLev,

The 3-phase motors do not need a starter but the 1-phase do which increases the cost. Also, almost all high power motors are 3-phase. To use them with 1-phase current they are fitted with a converter (each of the 3 phases is alternating but the phases are delayed. the converter just creates 2 delayed and 1 non-delayed phases from a single phase). The most important characteristic of 3-phase motors is that they are extremely reliable since they have no brushes or inverters/converters.

If you have 3-phase current to your shop, you most definitely want to go with 3-phase motors.

Alin

-- -- Alin Dobra, Gainesville, Florida

Most if not all homes won’t have 3 phase power available. I have a 3 phase machining mill that I use a phase converter to run. Pretty cool being ability to reverse the direction with the flip of a switch. I can get it to stop instantly just by flipping the switch to reverse momentarily.

-- Gary, East TX -- The longest journey begins with a single step.

Thanks guys, no I don’t have 3 phase and for my needs,I probably will never get it either. I used to be an electrician, so I know all about phases, and was merely surprised that the 3 phase machines in the market are cheaper then the 1 phase machines. yes it’s cheaper to make them – but I figured that since 1 phase is more common, there would be less of a market for the 3 phase machines – making their prices higher (low demand – less people pay for a certain production – higher cost per unit)

right now I’m just running 110v, but later on I’ll probably upgrade, and install some 220v outlets. once I build up a shop from the ground up.

all said and done- 3 phase is just a really good current transmission.

-- My Drinking Club has a Woodworking Problem...

“I figured that since 1 phase is more common, there would be less of a market for the 3 phase machines – making their prices higher (low demand – less people pay for a certain production – higher cost per unit)”

I am pretty sure single phase is the minority. I believe 10 hp is the biggest single phase motor that is made. Businesses use 3 phase motors from fractional hp up to several thousand hp. A few years ago I hauled a 5,000 hp electric motor from Cincinnati to L.A. It weighed 25,000 lbs and had an 18” driveshaft.

-- David, Southern Indiana, http://www.freedhardwoods.com