Current in an Electromagnetic Coil

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SUMMARY

The discussion centers on the behavior of current in electromagnetic coils, specifically addressing the impact of insulation on current flow between touching conductors. The varnish-like coating on wires, which is typically rated for about a thousand volts, prevents significant current leakage and maintains the integrity of the coil's inductance. Using bare copper wires would lead to short circuits, eliminating turns and thus inductance, which is a critical failure mode in coils, motors, and generators. The necessity of insulation is emphasized, particularly when rewinding motors in industrial applications.

PREREQUISITES
  • Understanding of electromagnetic coil principles
  • Knowledge of electrical insulation materials and their voltage ratings
  • Familiarity with inductance and its role in coil functionality
  • Awareness of failure modes in electrical systems, particularly shorted turns
NEXT STEPS
  • Research the properties and applications of varnish-like insulation coatings for electrical wires
  • Learn about the implications of shorted turns in electromagnetic coils and their prevention
  • Explore the principles of inductance and its calculation in coil design
  • Investigate the effects of different conductor materials on coil performance and efficiency
USEFUL FOR

Electrical engineers, motor technicians, and anyone involved in the design or maintenance of electromagnetic coils and motors will benefit from this discussion.

Drakkith
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What keeps the current in an electromagnetic coil from moving between the touching conductors and instead go through the conductor? Is it the resistance being much higher between two touching sections of the coil? Is there a small amount of current "leaking" between each loop where they touch?
 
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The wires are insulated with a thin varnish-like coating. Usually good to about a thousand volts.
 
Is this typical in almost all applications of coils? Would bare copper wires result in a large loss in current through the coil, since the current is taking a "shortcut" to get through the circuit? Or does this depend on the overall resistance of the coil for a current moving through it?
 
The only exception would be a special bobbin that prevented conductors from touching. It is a very serious failure mode of a coil (or motor or generator) called a shorted turn. It can be catastrophic- think of it as a secondary turn that's shorted.
 
I agree with everything said here.

We have to make coil groups coated in a thin varnish, as antiphon stated when rewinding motors in our shop at work.

The coating depends on the motor operating voltages

But yeah, just using bare copper.. would surely result in a short circuit, there wouldn't be any turns and therefore no inductance.
 
Excellent! Thanks all!
 

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