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Why upgrade machine to 220v

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Forum topic by leftcoaster posted 07-02-2017 03:07 PM 978 views 0 times favorited 25 replies Add to Favorites Watch
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leftcoaster

192 posts in 717 days


07-02-2017 03:07 PM

I know that 220 opens up the possibility of larger motors. But suppose I have a machine that comes wired for 110 and for which I have enough amps to not worry about tripping a breaker.

What’s the argument for making the 220v upgrade in this case? Do things run cooler with lower amperage?


25 replies so far

View jonah's profile

jonah

1474 posts in 3139 days


#1 posted 07-02-2017 03:10 PM

Assuming that the wire is sized appropriately, there is no good argument for changing to 240V. With the right size wire, heat is not an issue.

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Andre

1497 posts in 1646 days


#2 posted 07-02-2017 03:19 PM

I assumed lower operating cost as around here we are charged by the KWh, so fewer amps used? When I switched a few machines to 220v they seem to start/run smoother.

-- Lifting one end of the plank.

View TheFridge's profile

TheFridge

8342 posts in 1326 days


#3 posted 07-02-2017 03:42 PM

Operating costs will be the same.

Lower amperage is a plus.

Technically there isn’t a difference on paper. In real life I find there is a small one. How it sounds when starting and in use is one.

-- Shooting down the walls of heartache. Bang bang. I am. The warrior.

View Fred Hargis's profile

Fred Hargis

4771 posts in 2334 days


#4 posted 07-02-2017 03:48 PM



Operating costs will be the same.

Lower amperage is a plus.

Technically there isn t a difference on paper. In real life I find there is a small one. How it sounds when starting and in use is one.

- TheFridge

That’s pretty much my opinion as well. But if you’re good with 120V, stay that way.

-- Our village hasn't lost it's idiot, he was elected to congress.

View Mainiac Matt 's profile

Mainiac Matt

7466 posts in 2169 days


#5 posted 07-02-2017 04:40 PM

W = V x A, so if you double V, you use 1/2 A, but the total power consumed will be essentially the same. Power companies bill by KWHr. (1,000 Watts pulled for 1 hour) so given the same W… Their is no theoretical savings.

But, as you push amps through a wire you create some thermal losses however (calked I squared R losses, where I is the current and R is the resistance in the wire). Copper, being an excellent conductor has a very, very low R value, so the heat generated is small, none the less, a 1 KW motor will have greater thermal losses running at 110 V than at 220 V, and thus will consume a little more power, and cost a few pennies more to run. In practicality, this is a very small factor.

But power is not the only consideration as torque also comes into play, and the motor will have more torque when powered by 220 V. This is primarily noticed when the motor starts and the 220 V motor will start more smoothly with less of a jolt and a lower current spike (so no dimming of the lights or tripping of breakers).

As noted by the OP, 220 V gets you into larger motors. Some don’t think this is a big deal as they run their “2 HP” DCs or “5 HP” shop vacs on 110 V, so who needs 220 V. But physics doesn’t lie… product marketers, on the other hand, do, and they create confusing terms such s “developed HP” or “peak HP” to muddy the waters.

In reality (just do the math) the maximum power you can get out of a 110 V, 15 amp circuit with an 80% efficient motor is 1 3/4 HP. If you want more than that, you need to go 220 V.

-- Pine is fine, but Oak's no joke!

View ArtMann's profile

ArtMann

691 posts in 656 days


#6 posted 07-02-2017 04:44 PM

Well, I am an electrical engineer and have spent a career dealing with these kinds of issues. If the wiring to the motor in question is adequate, then there is absolutely no difference in performance of the motor either way. That is a big “if” though. Furthermore, power is purchased by the watt, not by the amp. The wattage consumed by the motor is the same in either case. As an example, a 1.5 horsepower motor running at 120VAC and 15A can be reconfigured to run at 240VAV and 7.5A but the power is 1800 watts in either case.

There is one issue that makes 240VAC conversion a good idea. If you have an auxiliary breaker box that is fed by a 240VAC cable with a marginal current capacity, it is necessary to maintain a balanced load so that the load on either leg is not exceeded. Reconfiguring 120VAC motors to run on 240VAC will automatically distribute the load at 50/50. That is my situation.

View Mainiac Matt 's profile

Mainiac Matt

7466 posts in 2169 days


#7 posted 07-02-2017 04:53 PM

Three phase is the cat’s meow, as the motors do not required starting capacitors and don’t have a big current surge upon start up. Copper is expensive and you can power the same motor with fewer amps whe using 240 three phase, so your circuit will not require massive 10 or 8 gage cables and your installation costs are a lot lower.

-- Pine is fine, but Oak's no joke!

View Loren's profile

Loren

9643 posts in 3488 days


#8 posted 07-02-2017 05:07 PM

You can get by in woodworking running
110v machines only. The work will get done
slower, that’s all. Obviously some machine
types are only intended for professional
use so if you get into any kind of real
manufacturing of wood products 220
and even 3-phase power rapidly become
must-haves.

View AlaskaGuy's profile

AlaskaGuy

3662 posts in 2149 days


#9 posted 07-02-2017 05:08 PM


Three phase is the cat s meow, as the motors do not required starting capacitors and don t have a big current surge upon start up. Copper is expensive and you can power the same motor with fewer amps whe using 240 three phase, so your circuit will not require massive 10 or 8 gage cables and your installation costs are a lot lower.

- Mainiac Matt

There is a down side to 3 phase also. Unless you live in a commercial zone most of us can’t get 3phase power unless you buy and install a phase converter. That’s what I did and by the time I was finished I had almost $2000 in my system.

If and when I go to sell my equipment it’s going to be hard to do…... who knows how low I’ll have to go to sell them.

-- Alaskan's for Global warming!

View clin's profile

clin

754 posts in 836 days


#10 posted 07-02-2017 09:40 PM

Agree with the not much practical difference. But, the 240 V will have slightly more power becasue of the lower current. As discussed, less current results in less power loss in the wire (insignificant in terms of electric bill, if in fact it has any effect at all).

The higher current of the 120 V will drop 2X voltage in the power wires. This will result in slightly less voltage at the tool. The tool will therefore operate at a lower power.

A 50 ft run from your breaker box to the tool is not unusual and is probably on the short side. This would result in 100 ft, round trip, of wire. Assuming #12 wire, at 1.7 mOhms /ft, 100 ft results in 0.17 ohms of resistance.

Assume a 10 A draw. This results in a voltage drop of 1.7 V or about 1.4% of available voltage. Not huge, but not completely insignificant either. There is a bit of a complex interaction of the motor characteristics (power, torque, voltage, current and power factor). Therefore it isn’t simple to say exactly what the result would be. But in general the available torque is related to the square of the voltage.

So a drop of 1.4% of voltage would be in the range of 3-4% of torque compared to having no wire loss.

At 240 V, the nominal current is half (say 5 A), and the voltage is twice as large. So first off the voltage drop is now half or just 0.85 V and this is just 0.35% of the voltage. This results in about a 0.7% drop in torque compared to having no wiring loses.

So going to 240 V might give you about 2-3% more torque.

Of course actual torque draw depends on the cut being made so on ad so forth.

If it were me, I wouldn’t change it unless i had a problem I was trying to solve (like a need to reduce current on a shared circuit that trips a breaker). I doubt a few percent more in torque is going to be very noticeable or useful.

-- Clin

View Kelly's profile

Kelly

1821 posts in 2784 days


#11 posted 07-02-2017 10:54 PM

Except many of us are running everything through 20 amp circuits, so you can bump that a little. No?

In reality (just do the math) the maximum power you can get out of a 110 V, 15 amp circuit with an 80% efficient motor is 1 3/4 HP. If you want more than that, you need to go 220 V.

- Mainiac Matt


View Kelly's profile

Kelly

1821 posts in 2784 days


#12 posted 07-02-2017 10:58 PM

If much of what many say here is true, those who make fun of me for running ten gauge on all my 240 circuits are missing a critical piece of the puzzle.

View jbay's profile

jbay

1862 posts in 739 days


#13 posted 07-02-2017 11:07 PM


If and when I go to sell my equipment it s going to be hard to do…... who knows how low I ll have to go to sell them.

- AlaskaGuy

I’ll buy your stuff. Lets start with the Feldor…....

-- If anyone would like to see my Portfolio, PM me and I would be glad to send you the link.

View ArtMann's profile

ArtMann

691 posts in 656 days


#14 posted 07-02-2017 11:29 PM

I think it is smart to run all 30A 240V circuits but not for the reason you are giving. I like the flexibility to replace 3 hp machines with 5 hp machines without changing any wiring. The 1 or 2 percent difference you might get using heavier wire would not be detectable without sophisticated electro-mechanical load test equipment. It might be the same difference you would experience between a saw blade that is new and the same blade a week later.


If much of what many say here is true, those who make fun of me for running ten gauge on all my 240 circuits are missing a critical piece of the puzzle.

- Kelly


View Kelly's profile

Kelly

1821 posts in 2784 days


#15 posted 07-03-2017 12:19 AM

Actually, my whole reason for ten gauge is the “penny wise, pound foolish” thing (basically, what you said). Once the rock is on, the only way to get more power to an area of the shop is across the walls, rather than in them, AND it doesn’t hurt a thing to have too many clamps. I mean, too much capacity available at a plug. Of course, that doesn’t mean I’m going to feed my Unisaw with four ought.

There have been too many times, over the last fifty years, I needed more power, lucked out and got away with running a space heater off the same circuit as the TV and lights on a sixty amp fuse panel and so on..

As a kid, the experts KNEW we didn’t need more than sixty amps. Not much has changed. Today, the experts KNOW two hundred is over kill in many shops and homes. Sometimes they forget different parts of the country have different resources and needs. For example, I live just a few miles (literally) from two dams on the Columbia River and what folks on the cost pay three hundred for, I get for seventy.

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