Can this motor be wired for 110v?

Please don't think I'm stupid, but why can't a 220v motor be run on 110v? Wouldn't it just run half as fast? Electricity is not my strong suit.

No not that simple. it goes back to amps and volts . Lets use pluming and pipes as an illustration but not a direct correlation if you will.
VOlts have been compared to pressure in a pipe amps is the flow rate.

But try to pump water through a small pipe and only so much will flow it will take for the sake of argument twice as long to fill a bucket.

with wires the more flow you need the bigger the wire. the wires in your motor are designed for 3 amps based on 220v cut the voltage to 110 and the motor will attempt to draw the same power therefore 6 amps. but since the wire is too small for this flow the wire will act somewhat like a heating coil and generate heat. this heat generation will kill efficiency and potentially melt insulation and short out/burn out the motor.
I do not recommend trying it.
Tin

kd0afk said:

Please don't think I'm stupid, but why can't a 220v motor be run on 110v? Wouldn't it just run half as fast? Electricity is not my strong suit.

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An induction motor speed is controlled by the frequency of the supplied electricity.

You will probably find that it will run on 110 at its rated speed but its output power will fall dramatically.

A suitable transformer would be the cheapest option if you can't get at 220V.

HTH.

kd0afk said:

Please don't think I'm stupid, but why can't a 220v motor be run on 110v? Wouldn't it just run half as fast? Electricity is not my strong suit.

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This has been already covered by other but I'm going to try to add clarity (and probably confuse a few people)

AC machines have their rotational speed defined by the line frequency they run at. That is 60 HZ in the modern world. However most AC motors are not synchronized with the line frequency so the actual speed is the synchronous frequency minus slippage. Voltage has little to do with the motor trying to run at design speed.

This is why 3 phase motors use variable frequency drives to change their operating speed. These drives do vary the voltage slightly to the motor but that isn't done to change speeds so much as to deal with other issues.

Now why can't you run a motor at a reduced voltage, if it is frequency dependent? That gets involved in motor design to a greater extent than we really want to get into, but in simple terms the winding are design to operate at a specific voltage or sets of voltages.

Hi Wizard69,

It seems nitpicking but I would replace the words "AC machines" by "Induction Motors". Simply because an ac machine could be a universal motor which could equally well run from an ac or dc supply and also be voltage dependant for its speed.

RonGinger said:

This is getting a little of the mark. We are measured for our POWER drawn, not just the amps. So if we use 1hp of mechanical we will pay for 1hp+ some loss of electricity. It doesnt rally matter if we use the power at 110v or 220v, power is power. Transformers happen to be about the most efficient electrical gadget around, so if use one to change voltage we use very little more power.

It is true that the same motor, doing the same work, will take twice the current flow at 110 as at 220. But 2x current at 1/2x voltage is still the same power.

The reason we want to run the motor at the higher voltage is to lower the current, because the current will cause a power loss in the wires based on the wire resistance. So we like to run motors at the highest voltage, hence lowest current we can.

If the motor is run at 110v, the higher current will cause more line loss, and the voltage at the motor will be reduced from the 110 at the wall to maybe as low as 90 or so, the extra power lost to heat up the wires. So we waste power and the terminal voltage of the motor is lower so we get less power out of it.

When is all added up we are better off running a motor at 220v than at 110v if its possible.

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While your bottom line is true to a certain extent, unless large motors and long wire runs are involved, it is for all practical purposes moot. The motor in question, if it could be run on 120 v, would draw about 7 amps. Even an ordinary circuit of #14 wire on a 15 amp breaker would run this just fine, and most circuits today are usually #12 on a 20 amp breaker. It would take a very long run of #14 to reduce a 120 volt source to 90 volts when drawing 7 amps.

Here's a sample calculation for 500 feet of #14:
1 conductors per phase utilizing a #14 Copper conductor will limit the voltage drop to 5.64% or less when supplying 7.0 amps for 500 feet on a 120 volt system.
For Engineering Information Only:
15.0 Amps Rated ampacity of selected conductor
2.9495 Ohms Resistance (Ohms per 1000 feet)
0.058 Ohms Reactance (Ohms per 1000 feet)
24.0 volts maximum allowable voltage drop at 20%
18.759. Actual voltage drop loss at 5.64% for the circuit
0.9 Power Factor

Handy calculator here:
http://www.southwire.com/support/voltage-drop-calculator.htm

You guys are way above me electrically

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kd0afk said:

You guys are way above me electrically

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Hi kd0afk,

Understanding electricity is not easy. There is a lot of good, sound information in these few posts. The bottom line is, simply get access to a 220 volts supply or replace the motor with one having the correct voltage. As I said earlier a transformer will do what you want and should be way less costly than a new motor.

So now that you solved that, how can I make my sewing machine motor AC 110v universal type, run backwards.

barnesrickw said:

So now that you solved that, how can I make my sewing machine motor AC 110v universal type, run backwards.

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Reposition the brushes!

On edit: If it's universal, run it on DC! Polarity then determines direction.

Usually it's quite easy to get a a 220V motor running on 110V. That motor is a 2 pole motor and the windings (1 pair of coils each start run) should be connected in series. If this is the case, they can be reconnected in parallel without the need to rewind it. A little patience and you can do it yourself. I've had a motor repair shop for many years and I've done it before. If you want "long distance" help, I can walk you through it.

BaronJ said:

Hi Wizard69,



It seems nitpicking but I would replace the words "AC machines" by "Induction Motors". Simply because an ac machine could be a universal motor which could equally well run from an ac or dc supply and also be voltage dependant for its speed.

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You are right of course. There are actually a number of motor designs out there but in the case of machinery the vast majority if the AC motors are of the induction type! If you work with them on an almost daily basis you forget about all of the variations.

BaronJ said:

Hi kd0afk,



Understanding electricity is not easy.

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I wouldn't say it is difficult but formal education does help. Motors where covered in part of one quarter of my electrical mechanical technology program. It is one part of my education that has actually been helpful after finishing that two year program. That and I managed to take an industrial electricity course at a tech school night program one fall.

It isn't that the subject matter is difficult it is just that you don't get exposed to it at all during most educational experiences.

There is a lot of good, sound information in these few posts. The bottom line is, simply get access to a 220 volts supply or replace the motor with one having the correct voltage. As I said earlier a transformer will do what you want and should be way less costly than a new motor.

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Personally I'd install the 220 circuit or in the case of this poster have an electrician do it. The circuit will be very useful for an air compressor, small mig or inverter welder or other tools that migrate to the shop.

Speaking of circuits I have one branch circuit waiting on an install in the cellar right now.

Alchymist said:

Reposition the brushes!

On edit: If it's universal, run it on DC! Polarity then determines direction.

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Yes ! That's the easy way...

The hard way is to swap the ends of the field winding. Near impossible to do on some motors.


As an aside:
I have a universal fractional horse power motor, very similar to your sewing machine one. Its a 100 watts rating that started life on a Creed Teleprinter. It was made in 1947 by LFM. It has a very useful 3/8" shaft and runs at a nominal 3000 rpm. The ends of both field windings come out to a terminal block mounted on the side. This terminal block is marked 110v, 220v with a flying lead on each side. Swapping these wires around will cause the motor to run the other way on AC. The motor originally was set up to run on DC 100volts This was because the motor when set up on the teleprinter had a large centrifugal governor that broke the supply voltage when the speed went above 3000 rpm.

This motor currently drives my small drill grinder via a triac speed controller.

Correct me if I am wrong but with 220V you would have 2 hot leads that are 110v each that are out of phase. If you used a transformer and upped the 110V to 220V you would have 1 hot lead that was 220V I don't think this would work to run a 220V motor Mike

This use of 'phase' is widely misused. In fact the wire coming into your home is from the 2 ends of a transformer out on the pole. This transformer has a center tap, so from the center tap to either end you find 120v. The 240v wires are the same phase, but will be opposite in polarity- one end goes plus while the other end goes minus. But its still only one phase.

Many people, electricians included, will refer to these two wires as phases but they are not.

If you take a 2:1 ratio transformer, hook it to the 120 v line and neutral, the transformer will have exactly the same output as the two wires coming into the house- one end will be positive while the other is negative. What you will not have is that circuit reference to neutral, or ground. It will run the 240v motor just fine.

I have a 3/4hp 110v motor that only runs at 1750rpm. I use a larger pulley on the motor to double the speed right? It shouldn't hurt performance right?

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The reason why I don't install a 220 line in the garage is because I rent and the landlord is a butt hole. The garage my tools are in has 4'x8' storage units for the tenents and a common area. My lathe is in my unit. There is also a back room to the garage; 12'x25'. I've asked him on several occasions to rent the space for a $150/month but he says he needs it for his maintenance guy. His maintenance guy has NEVER been in the garage once.
It wasn't "no, that's not not enough money", or "I'm renting it out already". I don't understand people. I was given a Fleetwood motorhome a few months back and I was going to fix it up and sell it. The landlord told me it had to go. He gave me a time limit to move it that didn't give me a chance to sell it so I had to pay to have it hauled away. The motor needed some work but the body was in pristine condition so it wasn't an eyesore. I explained that if he gave me a month it would be gone and I could make some money by selling it. He said he couldn't have it. I live in a industrial/residential area and it was not out of place and the neighbors were fine with it. The landlord lives two towns over also.
How do you deal with a guy like that?

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bb218 said:

Correct me if I am wrong but with 220V you would have 2 hot leads that are 110v each that are out of phase. If you used a transformer and upped the 110V to 220V you would have 1 hot lead that was 220V I don't think this would work to run a 220V motor Mike

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You are wrong. Notice in the crude drawing, a 240 volt motor would normally connect to points A and C in the main panel drawing. By using a step up transformer as in the motor circuit shown, the motor sees the exact same 240 volts as it would if wired direct.Transformers are neat devices, can step voltages up and down, provide taps, references, etc, and are one of the few devices almost 100% efficient.

kd0afk said:

I have a 3/4hp 110v motor that only runs at 1750rpm. I use a larger pulley on the motor to double the speed right? It shouldn't hurt performance right?

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Depends on your definition of performance. There are two factors to consider - speed and torque, torque being the amount of twisting force applied to the load. A given motor running at say 1750 rpm, will develop a fixed amount of torque at that speed. Ignoring minor factors, putting a small (say 2")pulley on the motor, and a 4" on the load, the load will be driven at half the motor speed, (875 rpm), but with twice the available torque.

Reverse the pulleys, with the 4" on the motor and the two inch on the load, the load will be driven at twice the motor speed, but with only half the torque available.

In essence the speed is determined by the load requirements, and pulley sizes selected to produce that load speed. Torque, on the other hand, is also determined by the load requirements, and is achieved by selecting the right sized motor - the more torque required at the speeds and pullies selected, the bigger the motor needs to be. Hope this helps.