# How rotor windings are connected to the power physically?

Discussion in 'General Electronics Chat' started by logicman112, Jan 1, 2011.

1. ### logicman112 Thread Starter Active Member

Dec 27, 2008
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I wonder if anybody can attach a picture showing how rotor coils are connected to the power supply in an electric machine.
Imagine we have two wires out of our electric plug, how these wires are connected to the rotor part and it rotates while those wires are not twisted?
The machine text talks about a rotating mechanical contact, i wonder if anybody can attach a clear picture from it.

Aug 30, 2007
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3. ### shortbus AAC Fanatic!

Sep 30, 2009
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If your talking about AC - Mains motors, Quote- " Imagine we have two wires out of our electric plug" Most AC motors do not use a direct connection to the rotor. That type of motor has a 'stator'. the stator is a set of coils that surround the rotor and magnetically move the rotor to do the turning/work.

See this; http://en.wikipedia.org/wiki/Induction_motor

4. ### logicman112 Thread Starter Active Member

Dec 27, 2008
69
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I wanted to see a clear picture of brush-commutator.
Another question: How current is given to the rotor of brush-less motors?

5. ### GetDeviceInfo Senior Member

Jun 7, 2009
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current in a brushless rotor is induced, hence the term 'induction' motors.

6. ### kubeek AAC Fanatic!

Sep 20, 2005
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Or if they are brushless DC motors the rotor is usually permanent magnet.

Dec 26, 2010
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Alternators often use brushes with slip rings.

8. ### #12 Expert

Nov 30, 2010
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Current is not physically connected to the rotor of a brush-less motor. The rotor is moved with a magnetic field and the magnetic field causes a current in the rotor.

Just trying to clarify by using different words and longer sentences.

9. ### logicman112 Thread Starter Active Member

Dec 27, 2008
69
3
Thank you all for the replies. I have heard that in some motors, current is given to the rotor by an electronic circuit without real physical contact or induction. (Hall effect is used). I wonder if anybody knows about it.

10. ### thatoneguy AAC Fanatic!

Feb 19, 2009
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The Hall Effect is what causes semiconductors, such as transistors, to change properties (usually conduct) when in the presence of a magnetic field.

Hall Effect Sensors are used in conjunction with a permanent magnet connected to a rotating shaft to measure RPM and similar.

All "standard" motors use electromagnets for rotation. Some coil is energized at some point. If the coil is fed AC and there are no actual permanent magnets, it is an induction motor. If both the rotor and stator are electromagnets, it has slip rings or brushes. Brushless motors run with a permanent magnet rotor and "rotate" the magnetic field, typically with 3 phases (created through a controller). BLDC (Brushless DC) Motors may have a Hall Effect sensor in the feedback loop to the controlling circuitry.