DC Stator Ring Question

You REALLY need a better understanding of electrical power before you start messing around with things like this. From your questions, I can easily gather that you are fast on your way to experiencing the negative side effects of getting in too deep into electrical applications.

Then I will make a mistake and learn from it. I am currently a physics major with a minor in mathematics and electrical engineering and the only way to really learn about how electromagnetism and electronics work is to work with them, which is also why I am taking safety precautions to protect myself.

Does anyone have any answers or ideas concerning my number of windings per coil question or whether DC or AC power is better for a stator ring and would the 6 coils be connected together in the delta or star shape no matter DC or AC power and how would the interconnected coils be connected to the AC or DC power supplies???

Please do not discourage the furthering of knowledge by saying I need a better understanding. Be a stand up guy and share that knowledge with me. Saying I should stop experimenting and learning will fall on deaf ears with me...I have been building and playing with electronics, computers, circuit boards, and robotics all of my life and will not stop furthering my knowledge, which is why I have posed the questions I have.

Thanks.

Stephen

I looked at the website and saw that using DC I would need a rectifier to change the wall AC to DC. How much are these rectifiers? Where can I find them?

The website did not, however, tell me how to figure out how many turns per coil is needed for my steel stator ring with 6 coils. Does anyone have any ideas?

Thanks.

Stephen

Let's start with the basics. It sounds like you need some guidance in electromagnetics. Here's a link to a intro book via Amazon.

http://www.amazon.com/Schaums-Outline-Electromagnetics-Joseph-Edminister/dp/0070212341

I assume you've googled and checked Wikipedia for help, but if not start with this link.

http://en.wikipedia.org/wiki/Rotating_magnetic_field

The problem with a request such as yours is that it requires a lot of background info and specific details to know exactly what you are planning to do, to formulate an intelligent response; and likewise you're asking people to provide you with a lot of information, essentially working out your problem for you.

Radio Shack has the rectifiers for about $5 and the qire too.

As the previous post stated, you are being a bit vague about what kind of stator you are trying to make.

You can make one out of old CD discs if you are just playing around.

The length of wire will vary from 15 feet to 200 feet depending on what wattage you want to make. 28 guage copper wire with enamel coating will work.

If you have access to an old junk motorcycle, take the left side cover off and you will see what one looks like.

What country are you in?

Guys...From all the stuff I've read, which has been a lot as I am a junior in college with a major in Physics and a minor in mathematics and electrical engineering, a stator ring is a steel ring with 6-coils for 2 poles connected in a delta or star pattern and powered by a three-phase ac power source which the rectifier will give to create a rotating magnetic field. I have all gauges of magnetic wire, so it really is what gauge works best, which is what I am asking for guidance on. With a steel stator ring with the coils being about 1 inch in length with probably 14 gauge magnetic wire, how many turns are needed per coil to get a strength of about 1.3T? Because the rectifier can tuned to different frequencies, I am unsure of the which frequency would be best, do you guys have any suggestions?

I really do not know how to be more specific than that. If you need more information then please ask me the specific questions than just saying it is "too vauge" as that does not help me answer what information you need.

You can begin by calling things by their proper names. It's MAGNET wire, not "magnetic" wire.

If you were as earnest about seeking help as you claim to be, you would come to class better prepared. Try reading Electricity 1-7 by Harry Mileaf as an introduction. The electrical and magnetic facts of life at DC and low frequencies are well-known and have been extensively characterized for a very long time.

By the way, a rectifier has absolutely nothing to do with a magnetic field, rotating or otherwise.

Stephen420,

bubbaPebi got it right. I don't know what physics and ee classes you attend, but I don't think you are learning much that is useful.

1. To cause the rotating magnetic field, you don't need any DC or rectifiers. The 3 phase AC will do the job. You have to settle on the size and right kind of laminated steel or other core material appropriate with enough area so that the field will reach 1.5T without saturating the core. Only you know the frequency and this will determine the core materials that may be appropriate.

2. If you are not using 50, 60, or 400 Hz, you have a greatly enlarged problem. You have to generate the 3phase electric power! I think you had better post another question link, if that is the path you take.

3. As you should know the number of ampere turns required will depend on the core permiability, area, and dimensions of any air gaps to the return path. The wire size needed depends on the voltage, resistivity and cooling available for both the core and the wire (see wire tables) assuming you will use standard enameled copper wire. If you will be doing some work with this rotating field you can apply Lenz Law from the motion of the permanent magnets used to determine the back EMF to adjust the wire size. The current in the windings depend upon the sum of the work done and the magnetizing current for the core.

4. Now you see some of the complexity of the question you pose. If you have no permanent magnets, you must be using coils with DC, maybe you need rectifiers who knew! If you were clearer, you might get better answers.

Luther M

Luther M

Now that we have established that I am a college kid and still have a lot more to learn.................

I am trying to build a simple steel stator ring with 6-coils, that are about 1 inch in length, for 2 poles connected in a delta or star pattern and powered by a three-phase ac power source which the frequency inverter from Radio-Shack (The frequency inverter was suggested by someone on this CR4 forum to turn a DC 20A variable power supply to 3-phase AC, or turning a wall socket hot and neutral into 3-phase AC, so if this is not correct please give me another suggestion to get the 3-phase AC power other than a 300 dollar 3-phase power supply as I am a college kid and cannot afford it) to create a rotating magnetic field. I have all gauges of magnetic, or MAGNET, wire, so it really is what gauge works best, which is what I am asking for guidance on. With a steel stator ring with the coils being about 1 inch in length with probably 14 gauge magnetic, or MAGNET, wire, how many turns are needed per coil to get a strength of about 1.3T? Because the frequency inverter can tuned to different frequencies, I am unsure of the which frequency would be best, do you guys have any suggestions?

If this isn't enough information please tell me specifically what is needed so I can find that information out to share with you guys to get my ultimate question about the number of turns per coil is needed.

Thanks.

Stephen

Sounds like what you are trying to build is an electric motor.

A stator produces electricity.

Plugging it into a wall socket with an inverter will make it turn but it becomes a motor at that point and doesn't produce electricity, it uses it to create torque and heat.

Stephen.

You need to know what is a rotating magnetic field. This was explained in the previous instance of this same thread. You can also get some books from the technical school library that deals with Electrical motors and Generators. This is a course that can be taken. I do not know how to guide you on the course since I am not lving in the same place...

"Magnetic wire" is a jargon term. There is nothing like that in reality. What it is: Simply a copper wire covered by an enamel coating of different types to insulate the copper conductor from adjacent coils, when being coiled. The different types will have to do with Insulation class definitions which indicates the maximum teperature they can cope with without burning or degrading and loose their insulating property.

DC current cannot generate a rotating magnetic field just like that: A DC motor usually uses a Commutator device with brushes to switch on and off different coil sets on the rotor, thus directing the current in a way to create a force due to the magnetic field (Stationary) on the Stator.The theory and course exist in the schools and libraries. You do not need to ask someone to work it out for you because it will be long etc...

Calculating the number of windings and the wire gauge for a particular application: We cannot say that such a particular wire gauge will be suitable or not to produce 1.2T field. You need to know the Groove size (where the wire is going to be lodged in) and the overall design of the ring. Also, the number of turns required for the field targeted is required to select the gauge.

To obtain the whole information so as to decide on the number of windings and the gauge etc you need to make some arbitrary choices and compromises: You need to know about Ampere x Turns; Voltage and current that will flow; The Steel core being used for the stator in question, magnetic permeability value and some more.

There are some formulae that are used as rule of thumb for specific applications like making a coil for a relay or building a transformer ... But all need to be related to some manufacturer supplying the steel sheets and some data.

This is a long story. I am not an expert in this field which is more a technical field to be dealt with by someone having some experience in winding and designing such equipment involving magnetic fields. I Hope Someone in this forum has that expertise to guide you and is willing to to it.

Cheers.

From the Georgia Tech Physics Dept. web pages I found that this past Spring E&M was taught by professor Ballantyne: [3123 Electrodynamics Ballantyne]. I also found a listing of dozens of other faculty members in the department, many of whom would be able to take a look at what you are trying to build and give you first-hand suggestions on what you need, and probably even open a lab for you and offer you some power supplies, signal generators, and other gear (including magnetic or MAGNET wire) to get you going. They'd probably even point you to the chapter in your E&M book on how to calculate field strength from turns, current, etc.

So why don't you drag your whiny little a$$ over to the Joseph H. Howey Physics building and ask your ADVISOR for some help, or Dr. Ballantyne, or (if they both happen to be gone for the summer) ask the department secretary to suggest a professor who might be willing to help you. Maybe even on of the seniors in the Physics department might be willing to help you, if you haven't already pissed them all off.

And I'm probably wasting my time with this, but let me again point you toward the Schaum's outline book on electricity and magnetism, that I mentioned in a previous reply; which you apparently ignored.

Rudy! GA from me.

Thank you for answering all the points. I can use all the formulae you shown here. I hope Stephen will learn something.

MY GOD GUYS.....I POSTED THIS SAME QUESTION A MONTH AGO AND ASKED SPECIFICALLY IF I WOULD USE THE SOLENOID FORMULA B=mu*N*I and NO ONE,NO ONE ANSWERED!!! SO I TRIED THE NON MATH ROUTE BY TRYING TO EXPLAIN IN WORDS WHAT I WANTED TO DO!!!

Thanks rudy!!!

But let me just say this, I am a 4.0GPA student and have asked my professors about this...LETS SEE TO USE THEIR LABS AND EQUIPMENT I have to fill out a ton of forums and take a specific lab class extra, payed out of pocket which would be about a 1000 dollars, to be able to even registar for a lab.

MY PHYSICS ADVISOR told me that you guys at this forum would help me gladly... Jezz would he be so disappointed.

LOOK UP MY POSTS SOMETIME AND YOU GUYS WILL SEE I ASKED SPECIFICALLY ABOUT THAT FORMULA AND NO ONE ANSWERED.

Thanks very much Rudy for conformation on my formula, was that so hard.....

Now that I have calmed down....

Let me apologize for my scathing posts. I was just so angry with the posts "You need a better understanding...Go find the information yourself...For a college student you should go talk to your professors....etc" Do you think I haven't done those things before posting?

I got this forum name from my Physics Adviser since Undergraduates really cannot get lab time, since all of the time is given to the grad students. I asked a total of 5 physics and engineering professors and none could answer my question....3 told me to go to this forum and physicsforum.org....so being a really good student that is what I did.

I am all good with reading and finding information myself but I could not find if I would use the solenoid formula B=mu*N*I for each coil in the stator...I asked this exact question a month ago and got no response...so I tried to put what I wanted to do in words....I always thought that the stator had to be 3-Phase AC powered, but someone on THIS forum said that I could use my DC 20A variable power supply...check out my posts....It was really the condescending attitude that really bugged me...I just could not understand why people were being so condescending instead of saying "I don't know" or "Have you tried this formula" or "Is your set up like this...?" I am just saying that people will respond and learn and be inspired more by kindness and willingness to help than condescending attitudes and "You REALLY need a better understanding of electronics." Well no kidding, what do you think I am doing.....

Anyway thanks for answering my question and confirming that I would use the formula B=mu*N*I for each coil. I really appreciate it.

Stephen

OH and I went to the bookstore and looked at each of the books you guys suggested and all they said was that a stator ring is used to create a rotating magnetic field to turn the rotor of an electric motor and that most stator rings have 6 coils and are powered by 3-phase AC power, however.....

none told me the formula to use to find out how many turns for each coil like Rudy did, so while I appreciate the titles, none of them answered my ultimate question which Rudy answered.

I have to admit, I'm surprised that getting some help at GaTech is so difficult, and expensive. Your comments aren't very encouraging to other students thinking about going there. As an undergrad, I went to a university that had a small but active Physics department. All the students and professors knew each other and if you needed to use a lab or borrow an o'scope or other piece of equipment, you could usually find a professor willing to open a lab and offer some help. I'm sorry I was a bit snarky in my previous reply, though if you'd explained what you had tried to do to get some help, to no avail, I (we all) might have understood your situation a bit better.

I'm glad you got some help, and I hope your project goes well.