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Rewiring a Compressor Motor

06/24/2009 7:48 AM

can anyone help me.i have an air compressor motor and want to rewire it so that it can generate 220v at low RPM

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Guru
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#1

Re: wind power

06/24/2009 7:58 AM

Assuming it to be an AC motor, which isn't stated in the post, something has to generate the magnetic field needed to produce the voltage at the output terminals. So, where does the power source that energises the stator winding come from?

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#2
In reply to #1

Re: wind power

06/24/2009 9:06 AM

i want it from the wind thats why i say low RPM

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Guru
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#3
In reply to #2

Re: wind power

06/24/2009 9:29 AM

So how is the magnetic field needed to turn this motor into a generator to be provided?

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#4
In reply to #3

Re: wind power

06/24/2009 9:49 AM

ANYWAY MY PROBLEM IS I WANT SOMETHING THAT CAN PRODUCE CURRENT EITHER AC OR DC TO POWER MY HOUSE. IF CAR ALTERNATOR IS POSSIBLE HOW CAN I DO IT.

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Guru
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#6
In reply to #4

Re: wind power

06/24/2009 10:34 AM

Please turn off Caps lock.

An alternator has a fixed magnet inside it, and is designed to produce an AC output from a rotating input shaft, so that's OK.

A parallel-wound AC motor will not produce an output while rotating until a magnetic field is created within it. The only way to do this is to separate the stator winding and the rotor winding, and energise the stator winding separately. So, once again, the question is: for the use of a motor as a generator as originally posted:

  • where is the power needed to create the magnetic field going to come from?
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#8
In reply to #6

rewinding a motor from ac to dc

07/09/2010 4:24 AM

I understand that the stator needs to be separated from the rotor. In an AC motor how would that physically be accomplished. By separating the wires that go to the stator and brushes. Then applying a constant DC voltage to the stator. Then apply the supply voltage to the rotor. In a dc motor this could be from a PWM controller. Is this the basic idea? If I am way off please give it to me gently. My desired goal is to maybe rewire a large 10hp to 20hp ac motor to dc. This would be used in a project EV vehicle. I know that a lot of variables are missing. Lets say I was using 48v as my mains. Would the resulting motor be considered a sepex? I am somewhat new to this area. I have a better than basic knowledge of electricity and electonics, but not up to you all's par. If the concept is close let me know. Thankx

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Guru

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#5

Re: wind power

06/24/2009 10:06 AM

1. It is not proper to shout at (please keep the caps Off)

2. As is mentioned, there is not magnetic field. the Air compressor motors are likely to be induction motor and hence these do not have its magnetic field. For a generator (I assume you are not Electrical Engineer?)

To be very simply stated, there is a North Pole and a South Pole.

Inside these as the winding rotates, the induction effect creates the electrical current (moving conductor in a magnetic field - Faraday's law of Induction)

So for the current to generate - you need a pair of poles (at least one pair) and a moving or a rotating conductor in this field.

In Motors what happens is there is a rotating N-S pole and it pulls the other set of N-S pole (on Rotor) along with it - N of Stator locks to S of Rotor and vice versa.

These both fields can be generated from the supply and hence it does not necessarily need a supply independent magnetic field (the necessarily is mentioned since we have permanent magnet motors where there is a set of magnets on rotor or stator that locks to the rotating Field from supply)

For your case unfortunately you are not likely to have it.

So the best solution will be to rewire the rotor to convert it into a DC excited (may be either excited by a battery or simply by putting some permanent magnet into it) and then you will have a generator.

But how much power you can get from this? that depends on the energy available on its driver and usually that is going to be quite low if you are thinking of a general wind driven, unless you can create a really large wind turbine.

Look at this thread where this have been discussed.

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Power-User
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#7

Re: Rewiring a Compressor Motor

07/04/2009 10:45 PM

Regardless of how you wire this "thing", the RPM required to generate from an induction motor typically used in an air compressor will require you to put on your Superman cape and spin that baby super fast. Same clothing attire is required for the car alternator thing.

Simply put, you will need to spin the induction motor from the air compressor above its rated RPM to begin generating electricity. Car A/C alternator idea requires also a higher RPM relative to that generated from a DC (magnet type) motor.

So your idea of using a low RPM generator using an AC motor assemblage relative to a DC driven motor will not be a reality.

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