1. OK, watts with 220?

I could have put this in lathe land but the question crosses over to all wood working tools. I asked this same question on another wood turning board last week but no one responded.
As most of you here know, I am a zero in the elektriks knowledge department. Most of the elektriks discussions leave me looking for a translator.
OK, I have gathered (learned?) that a 220V motor is better, or stronger, than a 110V.
But, what I haven't picked up yet is how much. e.g. Using my lathe motor as an example. It is a 1 1/2 hp., 220V, three phase (says that on it, but I don't know, or care what that means) and DC (I do know what that means, sorta). But, the puzzlement is: Is this 1 1/2 hp, or any 220V motor, stronger, or more powerful than a 110V 1 1/2 hp motor? If yes, why are both called 1 1/2 hp?
Last edited by Frank Fusco; 10-29-2008 at 07:23 PM. Reason: Rennie made me do it.

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Frank - the simple answer is: NO.

A 1.5hp motor is just that. Has nothing to do with the voltage at ALL.

Now. The reason it's so confusing is that some folks have witnessed performance increases when they take a "dual voltage" motor from 120v and rewire it to run at 240v. They almost always attribute this to the voltage being better, but in truth that is misapplied and very "post hoc ergo propter hoc". What it really tells you is that your 120v wiring was inadequate for the load and by going to 240v, you stumbled into a fancy scientific loophole that made it APPEAR to perform better when in reality, it wasn't performing properly at 120v to begin with. You weren't increasing the performance but eliminating a limiting factor caused by the wiring of the 120v circuit.

All that sounds lovely, dunnit? lol

The short answer to this question: Will rewiring to 240v increase my power? Maybe - if your 120v circuit isn't adequate for the load, rewiring to 240v MAY allow your motor to run at it's full potential.

The details as simply (and high-level, not super detailed) as I can put them:
The details are usually enough to make your eyes roll back into your head, but it really comes down to voltage drop. The thinner the wire, the more the voltage can drop when you're near it's maximum amperage. Oddly, when the voltage drops, motors tend to draw more amperage to compensate. This is bad juju for motors because they run hotter and all that fun stuff. By switching to 240, you are essentially dividing the load over two wires instead of one - thus halving the amperage draw on a given wire. This results in a lower voltage drop and therefore lower subsequent amperage increase. It's all the same power, watts is watts (which is just amps * volts - half the voltage, you double the amperage and vise versa).

In the end - 240v motors have no more power than their 120v equivalents provided they are adequately wired for that power.

3. Jason's got you covered. Watts is watts; if the electric company billed us by amps instead of watts, we'd all switch to higher voltages to reduce the amps drawn but financially it just doesn't work that way. I have a machine that will run 110 or 220v. I have it on a dedicated 110v circuit just as I would hve it on a dedicated circuit if it were wired for 220v. The performance is the same with all things being proper like wire gauge, etc.

Now your 3 phase vs. single phase I will leave to someone who actually knows what they are talking about ;-)

4. OK, wats with 220?

Frank,

As for the 3 phase motor part of this, I can only guess that your lathe is an "electronically variable speed" model? (I haven't kept up on your equipment too well.) If so, that would account for the 3 phase motor. The speed controller is probably changing the "frequency" of the current by way of a "variable frequency drive" to give you the variable speed feature and uses a 3 phase motor to do it. I am not that well versed on those but from what I have learned, a 1 phase motor doesn't work as well (or at all) in that respect. The way a 1 phase motor is speed controlled is by way of voltage change and the motor has to have "brushes" (as in a drill) to work. A DC motor would work the same way. (someone please correct me?)

Now, have I helped in mixing the mud clearer for you?

Aloha, Tony

5. I wired a table saw from 110V to 220V. It probably took 1.5 seconds to get up to speed. When I wired it to 220V it almost instantly jumped to speed. Actually scared me the first time. But, it didn't work any better. Just got up to speed quicker. I think that is where a lot of people get the idea there is more power. Because of the faster start up.

I wire most of mine 220V just because I can and I have 220 outlet all over the shop.

6. Jeff, Do you have each 220 volt outlet on a separate circuit?

I need to wire up at least one outlet, I'm getting tired of swapping out the plug on the dryer.

My house is 1978 vintage, and the breaker box is full up, but I don't think every circuit is being used. Someday I'll fully get them all mapped out.

We've got base board heat, so most a bunch of those are used up for 220 circuits for the heat, but I really think that I could 'swipe' one of the those 220's for my shop...

7. Yeah, the 3 phase is what's going to get you on this. Most of us don't have 3 phase power service. Those that have 3 phase equipment, but not 3 phase service use a convertor of some sort. Your's will need that, and will definately need to run the convertor on 220. Jim.

8. Originally Posted by Tony Baideme
Frank,

As for the 3 phase motor part of this, I can only guess that your lathe is an "electronically variable speed" model? (I haven't kept up on your equipment too well.) If so, that would account for the 3 phase motor. The speed controller is probably changing the "frequency" of the current by way of a "variable frequency drive" to give you the variable speed feature and uses a 3 phase motor to do it. I am not that well versed on those but from what I have learned, a 1 phase motor doesn't work as well (or at all) in that respect. The way a 1 phase motor is speed controlled is by way of voltage change and the motor has to have "brushes" (as in a drill) to work. A DC motor would work the same way. (someone please correct me?)

Now, have I helped in mixing the mud clearer for you?

Aloha, Tony
Yep, it is an electronic variable speedo thingy. It has a big box on the back of the unit I was told is the controller. Wadda I know? I turn the knob, it works.

9. Thanks all. That does help me know what I have. And, I understood most of it.

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Frank, Horsepower is a measure of work; one horsepower is 33,000 lb.ft./minute. Put another way, if you lift 33,000 pounds one foot over a period of one minute you produced one horsepower.

To put it in the simplest terms and not get in to the nitty gritty and the "buts" and "ifs"; it doesn't matter if that work is done with AC current or DC current, 12v, 24v, 110v, 220/1ph, 220v/3ph, 440v/3ph, 1750rpms, 3450rpms or bizzilion rpms.

Mike

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