# basic transformer winding question

Discussion in 'General Electronics Chat' started by dddmilch, May 3, 2012.

1. ### dddmilch Thread Starter New Member

May 3, 2012
2
0
Why are the primaries windings in transformers overlaping back and forth? Wouldnt that partially cancel some of the inductance?

2. ### Wendy Moderator

Mar 24, 2008
21,838
3,047
I'm not sure what you mean back and forth, they are a coil over the core, in all cases.

Can you give us an example?

While inductance does enter into it, the primary mechanism for a transformer is Counter EMF, same as with a motor.

3. ### SgtWookie Expert

Jul 17, 2007
22,201
1,809
The back-and-fourth winding doesn't cancel out inductance. If the winding reversed direction, THEN it would negatively affect it. If a wire accidentally is wrapped around itself forming a knot, that will goof things up as well.

4. ### dddmilch Thread Starter New Member

May 3, 2012
2
0
I understand that, my question was poorly phrased. Since the current is alternating across the wire linearly I assume that a coil isn't orientated perfect in phase with its neighboring wires at different lengths. So in some spots the inductive current would have constructive/destructive wave interference. Then wouldn't the output waveform be pseudo-chaotic? How could one wind a coil that the amplitude of the wave self reinforces at every point of mutual inductance? I can sorta figure it out for flat coil but the back and forth nature of most transformers makes the math really hairy. If only hysteresis didn't exist... lol

5. ### t_n_k AAC Fanatic!

Mar 6, 2009
5,448
790
There could be no traveling wave cancellation effects since the transformer winding is spatially distributed over a negligible fraction of the excitation frequency wavelength.

Ignoring leakage capacitive shunting the current at any point in the winding would be instantaneously the same. How could one then have flux cancellation if adjacent (parallel) conductors have the same current / field vector?

One would expect proximity effects to influence the distribution of current within the individual conductors.

http://en.wikipedia.org/wiki/Proximity_effect_%28electromagnetism%29