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  #1  
Old 11-13-2009, 03:40 AM
jeka616 jeka616 is offline
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Default Single phase series motor reversal

Hi all.

I got a "Naniwa" (chinese?) single phase series AC motor. I tried to reverse the rotor connections (brushes) as I figured out this is the way it is done in hand drill.

It is rated 220v/0.5 amps. I connect 2+5, 6+4, and connect 1,3 to 220v AC. Runs fine, 18,000rpm as stated.

The problem is, it runs fine in normal, but to reverse, I connect 2+6, 5+4, and 1,3 is 220v. It runs about 11,000 rpm, brushesh spark out , and gets warm soon.

My fear is , this is uni directional motor. Is there any way to change winding? I guess need to get my head around winding the motor...just don't have time. So previous experience is much appreciated..



There are 2 symmetrical stator windings, and one rotor with brushes.
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Old 11-13-2009, 04:57 AM
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I must admit that this is odd. The two wires that are connected to the brushes should be capable of being swapped.
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Old 11-13-2009, 02:47 PM
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Probably brush allignment; for bi-directional rotation, brushes are in-line with commutator diameter.
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Old 11-14-2009, 02:31 AM
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Quote:
Originally Posted by Bernard View Post
Probably brush allignment; for bi-directional rotation, brushes are in-line with commutator diameter.
I dismissed that thought but there doesn't seem to be any other obvious explanation. What was it that S. Holmes used to say....?
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Last edited by CDRIVE; 11-14-2009 at 01:48 PM.
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Old 11-14-2009, 05:48 AM
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good morning.

I was carefully monitoring the contact are of brushes , as soon as saw this problem. I'll try to file the brushes, so either direction the contact area is the same.
But...will this help? another question is, I don't have any cap hooked up into motor, should I put one? which contacts?

Thanks
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Old 11-14-2009, 01:59 PM
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Universal (Brush) Motors don't require Start Caps. They have very high stall torque. If you do find caps, they're usually very small disk caps, used to reduce RFI only.
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Old 11-16-2009, 03:25 AM
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I've managed to hook up stators to 12 v DC, and the rotor to ~45v DC. Runs ok, can reverse by reversing rotor connections. But, power is sacrificed obviously..


the next step, is to connect all in series, and hook up to DC, see how it runs..
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Old 11-16-2009, 04:06 AM
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Quote:
Originally Posted by jeka616 View Post
I've managed to hook up stators to 12 v DC, and the rotor to ~45v DC. Runs ok, can reverse by reversing rotor connections. But, power is sacrificed obviously..
If it's a series motor I would expect the the stator and Armature windings to divide up the supply voltage as per the manufacturer's design . Why have you been applying 12V to the Stators and 45V to the Armature? This may be partially the source of your excessive sparking but not certain.

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Originally Posted by jeka616 View Post
the next step, is to connect all in series, and hook up to DC, see how it runs..
Why haven't you been running it like this to start with?
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Old 11-16-2009, 05:17 AM
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I was testing at which current the stator windings start becoming warm, hooked up paralel to 12v DC, about 2.7A (a bit high for winded wire gauge), and in series connection almost draws 1.3A.

one thing I found out, is stator windings are ~3.6 Ohm each, and the rotor (single contact place) is ~28 Ohm some. So in series, much power will be dissipated by greater resistance, so staror should be ok.

the answer is, I was planning to have fixed connections on stator, and then remotely change rotor connections, to reverse with built relays with radio control.

I just thought about connecting stator and rotor in series to same supply source rather that separate. will try today.
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Old 11-16-2009, 02:07 PM
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Well you could have tested reversing the armature leads with everything in series to start with. These motors are popular for their high stall torque and variable speed using PWM. The schematic that Sgt. Wookie drew for the Split Phase Motor thread can be adapted to your motor.
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