Abnormal coil windings

[tuscan]

Does anyone know the likely effects on the magnetic fields produced if a coil is wound in a non linear fashion around a former. For example, if the wire was wound in a castellated pattern, i.e. around the former for part of a turn then along the former for a distance, then around the former for a further part of a turn then back along the former to the original position etc (square wave style) for the whole coil.
Would the main effect be that a higher current would be required to produce the same strength field as a conventionally wound coil or is there anything else to consider?

 

[BrianG]

Old-fashioned r.f. chokes had the winding split into segments to reduce the parasitic capacitance across the winding and hence increase its self-resonant frequency. Your winding at first sight seems to follow that style, except that you say that you only wind PART of a turn before you go back to the other winding.

Clearly the flux from each interconnecting wire between windings are going to be in opposite directions and so will cancel, so yes a higher current would be required to produce a given field strength. I can't see what benefit you expect to achieve with this type of construction.

 

[tuscan]

I should have been more specific I suppose. The coil is a degaussing coil in the hull of a ship. This is formed by one turn of a large multicore cable which effectively forms a number of turns. Due to the way the hull is constructed and equipment fitted, the cable cannot form a perfect loop around the hull and will have a number of deviations such as described in my question. The overall field we are trying to produce is in the vertical axis through the ship and I am interested as to whether these deviations will cause any problems. I have to produce a report for the system manufacturer detailing the deviations from their original design and am trying to pre-empt any technical reservations they may have. My feeling is that we can still maintain the effectiveness of the coil with the deviations described.

 

[waross]

It may be time to make a model and do some iron filing patterns. This will give you a good visualization of the field that you may expect. If one important factor is overlooked in a calculation, a computer simulation may be inaccurate.
Remember, the onus is not on real world to agree with calculations, the onus is on the calculations to agree with the real world.

Bill
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"Why not the best?"
Jimmy Carter