3 phase Dc?

[kenputer]

I have a 3 phase 230 volt dc motor, can this be used for wind gennie and what changes should I make to charge 12 volt battery bank?

[wdyasq]

I have a car with a 6 cylinder engine that uses regular gas.  It is blue.  What size tires do I need to achieve 32 pounds pressure?

Ron

[veewee77]

let me get this straight. . .

You have a 3phase. . .230 volt. . . DC motor?

Hmmm. . .three phase DC. . .that is interesting. . .

Actually if it is a servo motor, and operates on DC, it could have three phase windings in it and depending on if it has magnets or coils for the field or armature, it may produce current as it is, but you'll have to take out the DC - 3 hase converter in it and rectify the outputs.

Model of motor? Brand? (photo of info plate from it might work, too. . .)

Doug

[RP]

Wdyasq,

It depends.  Does it have leather upholstery?  ;-)

Seriously though, the comment said it was a 3hp motor.  If I'm reading this all correctly he's got a BIG brushless DC motor which ought to be make a really nice genny.

[pyrocasto]

I'm guessing he's meaning 3 phase AC...

Other's know more about it than me though. I'm only expert in the tire pressure area. ;-)

Ron, you need at least 3 tires to achieve that 32 psi per tire.

[zubbly]

hmm, 6 cylinder eh. thats a hard one. i suggest eating a mix of navy, black eyed and fava to change over to methane supply. use a clear flexible line from methane supply to air intake on engine. be careful not to sit on supply tube. this should change your colour from blue to a mellow yellow hue.

your tire size does not have to be changed at all!  Pressure will be determined by whether you have blonde, red, or brunette sitting beside you. if your pressure needs adjustment, be careful that the technition does not get a backfeed of methane.

hope this helps ya!

have fun, zubbly

[kenputer]

That is the what it looks to say on the tag and that is why there was a So thanks for the help from those that tried.

[drdongle]

It is an AC motor, designed to be driven by a 3 phase variable frequency drive, that has a DC input. Hence the confusing description.

And I might add, wow a great find.

[laskey]

Then it's most likely a Wound Rotor Induction Motor, and normally the DC to variable 3PH is in the form of  outboard drive electronics (sometimes known as a variable 3 phase chopper).

Anyway, what you've got is an AC motor that is designed to be driven with 230 Volts AC 3PH, at a Variable frequency, this gives (almost) constant torque at a variable speed.

See, I remember stuff from School.

Cya,

Chris

[ghurd]

I have seen a stepper type motor with 3 phases wired in wye.

Maybe that was more of a servo motor(?),

almost a EMC or F&P,

but they called it a stepper.

Like Dr. D said, good find.

G-

[Nando]

Kenputer:

First: inform about manufacturer, model, and any other characteristics you may know.

A 3 phase dc motor is a brushless 3 phase DC motor controlled by an electronic driving circuit that generate the 3 phases at the proper angle and energy to turn the motor at desired RPM with a certain power capabilities.

Examples of some of these types of motors would be the Smart Drive from Fisher & Paykel, and many other motors that are now available in the market, GE call them ECM.

Washing Machines like TROMM of Germany (LG Services) and MAYTAG do have such motors now.

Large air conditioning equipment are using the same type to reduce the Noise generated by the High speed of the air blowers.

NOW -- inform and you will not get the responses you got -- learn to be specific and clear -- so the responses are properly addressed to the questions on hand.

Regards

Nando

[Drives]

I have a couple of comments based from my experience.

1. I don't know what kind of motor it is unless I have more info...even a pic would help
   
2. Wdyasq, & Zubbly  you guys are a riot!
   
3. If it really is a motor with magnets in the rotor...it is not a standard 3 Phase AC "INDUCTION" motor.  It cannot be run be a standard 3 phase AC V/Hz variable frequency drive.  With magnets in the rotor it should be a AC servo, also called a DC brushless motor.  These take special "servo" drives that interface with the motor's feedback device to fire the appropriate output transistor to cause "magnetic interaction" and not mutual induction with the rotor.  If we tried to induce current to flow in the rotor, we would heat up the magnets, and "smoke" the motor.
   
4. I have never heard of a wound rotor motor as small as 3 HP...could be, but usually they are larger HP.
   
5. We never drive any motors with a constant voltage while varing the frequency.  We must maintain the proper V/Hz ratio to achieve the "constant torque" characteristic of the motor.
   
6. As for large air conditioning equipment using these types of motors...residential equipment I have no idea...when I think large, I think buildings 20 stories or larger.  We don't use AC servo or DC brushless...rather AC induction motors and VFD's.  The reason we use them is energy savings...look up the "affinity laws of pumps and fans".  Does this law look familar??  Amazing how the power from wind works to our advantage.
   
   

[laskey]

Well, I have to disagree with you on your point 5 there.  It's not only done, it's the only feasible way to do it for the applications they're used in.  Like say speed control of a modern diesel-electric train, or an ice-breaker, where you have to stop quickly and reverse, or you need all your torque at low RMPs.  Just imagine the abuse a mechanical gear system would endure under those kinds of uses.  No, What I'm talking about is an electronic drive system that gives you constant voltage from 5-1500 Hz, at enough Amps to do the job.  Normally we're talking hundreds of horse power, but you could do it on a smaller scale, there is nothing stopping you... just a reason to go to the trouble.  It is a bit of a pain to design and implement.

Cya,

Chris

[wdyasq]

Thanks for the tire advice guys.  Will it be safe to use them on a trailer?

Ron

[Drives]

Chris...Since I have spent 20 years in industry as a electronic drive specialist, and as a manufacture's rep for over 40 brands (GE, Square D, Toshiba, ABB, Danfoss, etc etc)....I believe you are incorrect.  We do not change the frequency while holding the voltage steady on AC induction motors.  Due to the inductive reactance of an AC induction motor if you fed it 1Hz at 230 Vac for example, you would "hopefully" draw excessively high currents, and fault the drive on an Over Current trip.  All AC VFD's have a usable current output up to 150% of the motor's full load amp (FLA) rating.  This is because AC induction motors can only produce usable torque directly proportional to current up to 150%.  Beyond 150% the current rises at an exponetial due to stauration of the motor.  200% torque equals 300% current.  To make a VFD rated above 150% FLA is very expensive due to power semiconductor costs.

To get extra torque out of a motor we can manipulate the V/Hz curve to "boost" the voltage at the low frequencies, however we never even approach half the motor's rated voltage.  That high of a voltage would cause the stauration, and unusable torque.

In the 230 vac range I have worked with up to 100 HP (manufactures don't make larger HP due to high cost), as for the 480 vac stuff it has been up to 2000HP.  

Chris...the main point is the ONLY way to change the speed of an AC induction motor is to change either it's number of poles (hard to do on the fly) or change the frequency to it....not the voltage.  We change the speed of DC motors by changing the voltage to the armature.

[Drives]

I have one more to add, we can change the speed of an AC induction via it's slip, however this is not a long term way of accomplishing the speed control task.  By slip control we hold the frequency steady but vary the voltage to control the current draw to the motor.  The same thing as putting a resistor in series with the motor to drop some voltage.  We typically do this with SCR's (Thyristors for you overseas folks) By ramping up the voltage to the motor during start up we can limit the current draw and achieve a "Soft Start".  We do not sustain this type of reduced voltage due to the fact that the motor will still draw higher than FLA at a reduced speed thus less cooling fan RPM's.  The motor will eventually burn up due to a sustained "brown out" condition.

[bryant wind electric]

Kenputer, I'd like to take a moment to apologize for the rude and sarcastic comments that you received from some members of this discussion board. It seems that some members are more interested in puffing out their chests and displaying their BIG EGOS, in effect, making it an " I know more than you " type of contest, rather than trying to help someone with their problems in a positive way. Take a good look at yourselves for Christs sake! In thirty years in the wind business, I have answered countless letters and now many, many emails from people all over the world. Not once do I recall ever having to be unnecessarily rude or sarcastic to anyone seeking my advice or guidance with their project. Apparantly, that is just too much for some of you. This used to be a good site, with good intentions, and a positive exchange of information. Try using your expertise to actually help someone rather than try and impress each other. This is not the only time that this has happened. Kenputer, again I apologize for your shoddy treatment. I would hope that other apologies would follow.

[ghurd]

I just got a 24VDC 3A 3-ph star wired stepper motor.

It makes 4.1VDC after rectification at 650RPMs.

Useless for me. Again. $60.  

So, they are out there. One way or another.

G-