Can't figure out electrical wires on DC motor

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  #1  
Old 11-03-14, 04:05 PM
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Can't figure out electrical wires on DC motor

I have this motor at work I'm trying to figure out. It has 3 wires and a ground that goes to the case. I was wondering if there was some way I could use an ohmmeter to figure out which wires are pos. and neg. There is no black and red on the leads, just random colors. On the data plate I see that the input is 28VDC at 15 Amps nominal. If someone could please help me figure this out I'd really appreciate it.

Thanx

Jim
 
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  #2  
Old 11-03-14, 04:23 PM
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Do you have a make and model number? What does the data plate say other than voltage and amps? A DC motor would normally have two wires. Is this multi speed or some special purpose motor. Easiest way to tell which is positive and which is negative is to power it up. If it runs backwards just reverse the leads.
 
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Old 11-03-14, 05:38 PM
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When you say ground , are you speaking of an earth ground or a ground , like on a car , that normally used the metal frame / body of the car as one conductor ( ground ) ?

The wires feeding the motor , do they origionate at a speed control or selector switch of some sort ?

God bless
Wyr
 
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Old 11-03-14, 08:03 PM
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Thank you for your replies.

Unfortunately ray I do not have a make or model number for the motor. The data plate really does not give any other info than volts and amps. And WyrTwister I think the wires are for some sort of speed control (which is no longer attached). And the ground is one of the wires coming out of the motor then is screwed to the motor housing. I think how I am going to proceed is to start out with a very low voltage (I have a variable power supply) and see what happens.

Jim
 
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Old 11-03-14, 08:06 PM
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I think how I am going to proceed is to start out with a very low voltage (I have a variable power supply) and see what happens.
That was my first thought but I tend to cautious recommending what I'd do to others when it involves smoke tests.
 
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Old 11-03-14, 08:12 PM
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Thanks for that thought ray.
 
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Old 11-03-14, 10:45 PM
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So many possibilities. Can you post a clear, in focus picture of the data plate? Otherwise tell use exactly what is printed on the data plate.

Also, tell us what type of use was made of the motor, if you know. 28 volts at 15 amperes would be about 1/2 horsepower. Speed, if given, is VERY important. Are all three wires the same gauge size or is one significantly smaller?
 
  #8  
Old 11-07-14, 05:39 PM
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OK. I've got some more info on this motor. I've attached some schematic diagrams. It looks to me like the motor is 3 phase. Or am I reading this wrong. It says on the data plate the motor is DC. So I'm a little stumped. I'll post a pic of the data plate as soon as I can.
Thanx

Jim
Name:  Scan.jpg
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  #9  
Old 11-07-14, 09:40 PM
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It's almost impossible to read the schematics but it looks like a three phase brushless delta motor. That is going to require a special power supply/controller to run it.

What are you planning on doing with that motor ?
 
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Old 11-08-14, 02:22 AM
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Yes , I tried to enlarge both jpg's and could not read them . Need a higher resolution scan or a link to an original file .

What little I can see , I would guess there is an electronic controller involved ?

I have read about the variable speed DC motors on the higher seer mini splits . Also read about variable speed fan motors on residential A/C - Furnace indoor units . Do not know if they are DC , but they have electronics as part of the motor , I think .

What does the motor operate ?

God bless
Wyr
 
  #11  
Old 11-08-14, 03:18 PM
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I'll try a higher resolution scan. We'll see if that helps.
Thanx for trying.

Jim
 
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Old 11-08-14, 04:27 PM
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You may have to post a higher res scan to an image sharing site or Dropbox and post the link.
 
  #13  
Old 11-08-14, 05:17 PM
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We still have no idea what you are doing with the motor. Those diagrams are pictorials. Enlarging them isn't going to help the situation much.

Are you connecting the motor to the circuit it was designed to be connected to or are you using that motor for a completely different use ?
 
  #14  
Old 11-08-14, 05:45 PM
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How about if I just post a link to the website where you can access the .pdf file.
http://www.woodward.com/Search.aspx?searchtext=em35mr1
What I'm actually doing is testing the actuator motor.

Mod note: Direct link to PDF: https://dl.dropboxusercontent.com/u/...ator_Motor.pdf

Thanx

Jim
 

Last edited by ray2047; 11-08-14 at 07:33 PM.
  #15  
Old 11-08-14, 07:57 PM
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The EM-35 actuator uses a brushless dc motor with a reducing planetary gearhead. The motor is designed with Samarium Cobalt permanent magnets bonded to the rotor element and all stator windings are completely sealed. Rotor position sensing is performed by the field director unit integral with the motor. This inductive device requires excitation and demodulation within the electronic motor controller.

The only thing you can do is to check for continuity between the three motor winding leads. You are not going to be able to run that motor without a 3 phase 28vdc power supply.
 
  #16  
Old 11-09-14, 07:49 AM
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Thanx PJmax. That's what I was starting to think. Where in the world would I get a 28 volt 3 phase power supply as they did not provide the electronics for the motor. Or could I rig something up. I'm pretty handy with electronics.

Jim
 
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