Three phase ac motors 110v help

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Discussion Overview

The discussion revolves around the challenges of operating a three-phase asynchronous motor rated at 110V and 6.9A, particularly in a residential setting where only single-phase AC power is available. Participants explore potential solutions for running the motor, including the feasibility of using a phase converter or switching to a single-phase motor.

Discussion Character

  • Technical explanation
  • Debate/contested
  • Exploratory

Main Points Raised

  • One participant describes the motor's behavior, noting it hums and spins slowly when turned on but stops under load, indicating potential issues with compatibility with single-phase power.
  • Another participant suggests selling the motor for scrap and purchasing a single-phase motor, citing the expense and complexity of converting to three-phase power.
  • A participant inquires about the motor's application and suggests that if it is for learning purposes, a phase converter could be a viable option.
  • Further specifications are discussed, including the need for a motor with similar dimensions and performance characteristics, such as horsepower and RPM.
  • Some participants express uncertainty about the motor's frequency (50Hz) and whether a higher horsepower motor would be beneficial.
  • One participant shares their experience of successfully using a phase converter to operate the motor, while another questions the cost-effectiveness of this solution compared to purchasing a single-phase motor.
  • There is a debate regarding the terminology of single-phase versus two-phase power, with some participants preferring to clarify distinctions while others express frustration over the ongoing argument.
  • Participants discuss the implications of using a single-phase motor, particularly regarding starting torque and mounting requirements.

Areas of Agreement / Disagreement

Participants express multiple competing views regarding the best approach to operate the motor, with no consensus on whether to use a phase converter or switch to a single-phase motor. The discussion also includes disagreements about the terminology related to phase power.

Contextual Notes

There are unresolved questions about the motor's specifications, such as rated temperature rise and shaft size, as well as the implications of using different types of motors in the specific application.

motorhed
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I have a motor i am trying to get to work. The tag on it says its a three phase asynchronous motor. 110v and i think the current is 6.9amps. When i turn it on it hums and if i spin the motor it will start to go and will spin very slowly but as soon as any resistance is applied it stops and just hums. Now i did some research online and from what i understand 3 phase has 3 hot legs and is generally used in industrial settings. I have this plugged into my regular wall outlet which to my understanding is 110v single phase a/c.
 
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motorhed said:
I have a motor i am trying to get to work. The tag on it says its a three phase asynchronous motor. 110v and i think the current is 6.9amps. When i turn it on it hums and if i spin the motor it will start to go and will spin very slowly but as soon as any resistance is applied it stops and just hums. Now i did some research online and from what i understand 3 phase has 3 hot legs and is generally used in industrial settings. I have this plugged into my regular wall outlet which to my understanding is 110v single phase a/c.

Unless this is a very valuable motor, sell it for scrap and buy a single phase motor. I'm guessing you're in the US; you have single phase (2 phase if you want to split hairs) and it's expensive to change.
 
motorhed said:
I have a motor i am trying to get to work. The tag on it says its a three phase asynchronous motor. 110v and i think the current is 6.9amps. When i turn it on it hums and if i spin the motor it will start to go and will spin very slowly but as soon as any resistance is applied it stops and just hums. Now i did some research online and from what i understand 3 phase has 3 hot legs and is generally used in industrial settings. I have this plugged into my regular wall outlet which to my understanding is 110v single phase a/c.

Why do you want to get it to run?
If it is for a specific application, then as suggested a single phase motor will cost between $50-100 US, and is the best thing to do.

If you are using it as a learning tool...?

An electrical shop might check it for free, or a small fee, if it is good then look at the following link.
A converter for that size motor looks to be around $100.00 US, and will change single phase to three phase.

http://www.phase-a-matic.com/PDF/SPL-2009-C.pdf
 
Last edited by a moderator:
It is actually for a machine. It just has a belt attached to it to spin. I have no problem buying a new motor but i want to pick one up preferably today or have one overnighted to me if anyone knows where i can get a similar one. Here is some more info on it, i need the new motor to be the same size as this one or similar because it is mounted to a bracket on the machine.

3 phase asynchronous motor
6.9A current
110v
1390 rev/min

That came straight off the tag.
 
I presume this is a 50Hz application. Is this correct? Is this a 1/2 HP motor? What is the rated temperature rise? What about shaft size, dimensional requirements, etc? Look in the Grainger catalog at
http://www.grainger.com/Grainger/wwg/productIndex.shtml?operator=retrieveProdLevel1Index&prodLevelList=Motor%257CMotors%252C&prod_level_selected=Motor
or at
http://www.usmotors.com/This_is_USEM/about008.htm
 
Last edited by a moderator:
I believe the motor on there now is 50hz. Not sure what the difference in application is. I just did some research and a similar motor i would need would need these specs.

3/4 HP, 1/60/110 volt drive, 1,400 rpm.

Would one with more HP be better?
 
http://www.made-in-china.com/image/2f0j00fCUETGtBFVblM/Y-Series-Three-Phase-Electric-Motor-Y802-4-.jpg

picture of motor
 
TVP45 said:
(2 phase if you want to split hairs)

Actually, I DO prefer to split hairs, and it is NOT 2 phase. Feel free to PM me or start another thread if you want to discuss it farther.
 
I'm assuming the picture is of the 3phase motor you want to replace. Keep in mind that a single phase motor of comparable size may not have the starting torque required to run whatever it is you're putting it on.
 
  • #10
starting torque is not a problem, i can manually get the machine going before i turn the motor on.
 
  • #11
motorhed said:
Would one with more HP be better?
Wouldn't hurt. It seems your main concern is mounting, shaft fit, RPM, and direction of rotation.
 
  • #12
Averagesupernova said:
Actually, I DO prefer to split hairs, and it is NOT 2 phase. Feel free to PM me or start another thread if you want to discuss it farther.

Lighten up. I put that in only because about third time I post on phase, somebody starts an ongoing argument. I'm too old to argue about this.
 
  • #13
well i brought it to a motor shop and he said easiest way was to get this box that converts 220v single phase to 3 phase, works like a charm now. cost me like 150bux tho.
 
  • #14
TVP45 said:
Lighten up. I put that in only because about third time I post on phase, somebody starts an ongoing argument. I'm too old to argue about this.

Then you shouldn't have brought it up. You are now forever excused from arguing about single vs. 2 phase. However, if anyone else has questions, I'd be glad to answer.
 
  • #15
motorhed said:
well i brought it to a motor shop and he said easiest way was to get this box that converts 220v single phase to 3 phase, works like a charm now. cost me like 150bux tho.
Are you sure you didn't get ripped off? Why couldn't he have sold you a single phase motor in the first place?
 
  • #16
He said a single phase was going to cost a lot more then the converter and would be a lot bigger and id have to make a whole new bracket to mount it. Problem solved so I am not rly worried about it, he was a nice guy and even let me go pick the part up without paying him until the next day and offered to help me wire the thing up if i needed help.
 
  • #17
Averagesupernova said:
Then you shouldn't have brought it up. You are now forever excused from arguing about single vs. 2 phase. However, if anyone else has questions, I'd be glad to answer.

Since you won't let it be, I'll take part in a discussion if you want. My only interest is historical, but I'd still like to see some good opinions on this since it's one of the perennial questions (What's the difference between bolts and screws? What's the difference between pipe and tube? Should single phase be called 2 phase?). So, if you want, go ahead and frame a question. I'll put in my two cents.
 
  • #18
There really isn't anything to that discussion. Here's a wiki on "two phase power": http://en.wikipedia.org/wiki/Two_phase

240V power is sort of in two phases, though, but it generally isn't called "two phase power" because it is actually just one phase of a 3 phase system that is then split in half. Ie, split phase: http://en.wikipedia.org/wiki/Split_phase
A split phase electricity distribution system is a 3-wire single-phase distribution system, commonly used in North America for single-family residential and light commercial (up to about 100 kVA) applications. It is the AC equivalent of the original Edison 3-wire direct current system. Its primary advantage is that it saves conductor material over a single ended single phase system while only requiring single phase on the supply side of the distribution transformer.[1] Since there are two live conductors in the system, it is sometimes incorrectly referred to as "two phase". To avoid confusion with split-phase motor start applications, it is appropriate to call this power distribution system a 3-wire, single-phase, mid-point neutral system.

In North America, the high leg delta system allows single-phase 120 V loads and 240 V three-phase loads both to be served by the same three-phase, four-wire distribution system.
No need for a heated debate.
 
  • #19
russ_watters said:
There really isn't anything to that discussion. Here's a wiki on "two phase power": http://en.wikipedia.org/wiki/Two_phase

240V power is sort of in two phases, though, but it generally isn't called "two phase power" because it is actually just one phase of a 3 phase system that is then split in half. Ie, split phase: http://en.wikipedia.org/wiki/Split_phase No need for a heated debate.

See? You could join in also. It's an endless discussion: Should we call it 120V 1Ph, 120V/120V 1Ph, 240V CT 1Ph, 120V 2 Ph, and so on? And, after that there's always the old one about "twist drills" vs "drill bits". Only engineers can truly love these arguments.o:) If we beat this to death, there's always the age-old tangent of "If Herman Westinghouse had been Edison's brother, would we be having this discussion?".
 
  • #20
It's only endless when someone will not admit defeat. The wiki article should make you realize why calling 3-wire single phase '2-phase' is incorrect.
 
  • #21
I thought perhaps you wanted to discuss this? If you only wanted to say I'm wrong, I never call it anything but single phase, CT, anyway.
 

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