Why Use Copper Coated Steel Wire in a Motor?

Never heard of it used in electric motors. For high tension lines, grounding fields, radio antennas, etc. (high frequency, high voltage, or corrosive environment) it has some advantages:

"

Advantages[edit]

Since the outer conductor layer is low-impedance copper, and only the center is higher impedance steel, the skin effect gives RF transmission lines with heavy copper-cladding a low impedance at high frequencies, equivalent to that of a solid copper wire.

Tensile strength of copper-clad steel conductors is greater than that of ordinary copper conductors permitting greater span lengths than with copper.

Another advantage is that smaller diameter copper-clad steel conductors may be used in coaxial cables, permitting higher impedance and smaller cable diameter than with copper conductors of similar strength.

Due to the inseparable union of the two metals and the low amount of the more costly one, it deters theft since copper recovery is impractical and thus has very little scrap value.

Installations with copper-clad steel conductors are generally accepted as fulfilling the legal specifications for a good electrical ground. For this reason its use is preferred by industrial companies and utilities when cost is a concern."

https://en.wikipedia.org/wiki/Copper-clad_steel#:~:text=Copper%2Dclad%20steel%20wire%20find,sometimes%20used%20for%20power%20transmission.

I don't recall any such conversation...I believe we did have a conversation about copper vs aluminum wound motors...this in an attempt to reduce cost and weight...but I don't recall the outcome..I do believe we were addressing the possibility of reducing the size of the aluminum wound motor by alternate designs...

..."Copper, material typically used for the windings of conventional electric motors, is more expensive and heavier than aluminium. For this reason as well, they have started the first experimentations of aluminium windings for electric motors, expected to replace a fundamental role, that is to say generating the electromagnetic field for the rotor.

Concerning this, protagonist is the British company Ricardo, which has started developing electric motors with aluminium windings intended for small-size electric cars.
Ricardo has been developing a rare-earth magnet-free sustainable electric motor concept with aluminium stator windings, which retains the key attributes of magnet-rich motors. The goal has been to create technology which is robust, costs less than current products and reduces lifecycle impact by eliminating the use of scarce resources for example up to 12kg of rare earth metals and also high acidification materials such as copper without impacting motor function or quality."....

https://www.electricmotorengineering.com/aluminium-windings/

Some progress has been made...

..."Among the results with the aluminum windings:

• The groove fill factor could be increased from 32 to 60%.
• At the same time, there was a weight saving of 10%.
• Torque increased by 30%.
• Due to the better thermal behavior of the coils, the continuous power at operating temperature increased by almost 20%.

The aluminum coil can deliver the resulting heat better to the laminated core and thus to the environment. This results in an improved continuous performance, since the coils only reach the permissible continuous operating temperature at higher currents.

Even more advantageous were the measurement results for a laminated core optimized on the cast coils in another modified pedelec motor. At lower weight, the torque increased by almost 80% and the continuous power by 25% compared to the original engine. Design changes can further increase the performance of aluminum coil motors."....

https://www.greencarcongress.com/2019/11/20191119-ifam.html

I still think there may be more to gain from material science increasing the conductivity of the aluminum used...

I think Lincoln Electric has been making aluminum-wound motors for decades.

While the use of Aluminium wire in Motors and Wiring Looms leads to weight and cost reduction, it has a penalty over the use of Copper and that is Space.
The Aluminium Wire requires about 20% more volume to replace the Copper Wire.
I worked on a project where one vehicle was a Porsche 911. The complete Wiring Harness weighed 50Kilos. Using Aluminium would have given a reduced weight of 46.2 Kilos but there was no room in the vehicle for a 20% increase in the Wiring Loom's size.

I see a lot of the motors and welder transformers at the dump skip and they are wound with aluminium and in some cases copper plated aluminium wire with the various types of insulating coating.

Having wound motors I would suspect that copper coated steel wire would be a right bugger to wind and form even when it is annealed as too is Aluminium.

Long ago we used to pull down copper power lines and replace them with high tensile steel cored aluminium wire and show a profit on the job as the disparity between scrap copper prices and aluminium cable was extreme.

When I knew a little about high tension transmission cables (from working with the poles holding them,) they were steel core for strength and aluminum for conduction. The utilities also sometimes used 4 conductors bundled together with spacers to increase the apparent size which reduced the corona losses. But that's electrical engineering stuff and I do not know the reason corona losses are reduced!

I have a very basic understanding of dc motors,in which the stator fields are reversed by the brushes of the commutator,and the back emf is neutralized by a compensator winding.In the aforementioned steel wire windings,the steel wire retains a residual magnetism and when properly timed by the commutator adds to the pole shift instead of having a compensator winding to absorb it and reducing brush arcing.Thus,the efficiency of the motor is improved.As far as I remember,this was the principle used in the motor I read about.

I do not know if this motor used any capacitors in the windings

Of course,what I read could have just been bunk.

I would like for a person much more knowledgeable on the subject than I am to comment on the feasibility and a deeper explanation of the reasons why or why not it is possible.I know much progress has been made in electric motors and this has probably now just a boat anchor,technology wise,if it was even possible.

Thanks for all of the comments from everyone.

When I was in the Army National Guard the wire used for perimeter defense in artillery units had 3 strands of steel (for strength) and 4 strands of copper. The steel was very stiff and inflexible. I would doubt that copper coated steel would be practical if even possible.

Perhaps this is the thread you are looking for:

https://cr4.globalspec.com/thread/86610/Magnetic-vs-Electrical-Propagation-Speed

I seem to remember that the electrons repel each other and thus the current travels in the wire surface by preference, and only deeper into the conductor as current approaches limiting factors. This is different to the skin effect mentioned for high frequency situations.

So a steel wire with copper coating would provide the current/magnetism required while the steel would ensure the field was developed across the relevant cross section.

The steel would probably need to be Lynamel or similar with very low magnetic remnance.

But this is only a hazy memory from 40 years ago.

The problem I see with copper coated steel windings besides the lower conductivity is that the "iron" which conducts the flux runs parallel with the copper which conducts the current. The flux from the current has to run perpendicular to the current carrying wire.

Here is a unique high performance motor type that uses axial flux motors. May be off topic, but still relevant.

https://yasa.com/applications/

An Axial Flux motor that is now owned by Mercedes and used in many hi-end vehicles and many manufacturers.. Very efficient compared to radial thrust motors.

4 Times the torque, and twice the power densities of current technologies.

50% lighter and only 20% of the depth of conventional radial flux motors.

https://yasa.com/technology/

Comments welcome.

Yeah, I was thinking that too, so the flux is at 90deg to the length of the wire. But in a winding it crosses itself quite a bit and must have a greater inductance as a result I would imagine.

Relevant: Teaser: Transforming Motion with Electrostatic Motors

From a Cost Engineering standpoint, here are the costs / Pros & cons of Pure Copper, Copper coated Alu and Copper coated Steel.
Pure Copper Wire. US $ 10,40 Kg Extremely flexible, perfectly suited to Electric motors of all sizes.
Copper / Aluminium Wire. US $ 6,33. Very flexible, Mix 15% Copper, 85% Alu. Suitable for electric motors but has about 20% increase in volume, offset by a weight saving of roughly 20% and a material cost saving of US $ 4.07, however the cost of coating the wire comes on to so not that much cost saving, main benefit weight !
Copper / Steel Wire. US $ 7.10 Kg Hard to bend, not suited for Electric motors. Mainly used in the Construction Industy for Earthing Cables. Material cost saving of US $ 3.30 Kg but again the coating process costs come on top so almost no savings. Minimal weight savings.
Conclusioms: the cost saving are negible and the only real benefit ist the weight savings generated in the Copper / Aluminium wire, assuming one has room for the increased volume, and there is clearly no benefits for trying to use Copper / Steel wire in an electric motor.

Initial cost is only one factor. An increase in performance and efficiency is enduring.

In an electric motor there is no advantage in using Copper / Steel wire irrespective of cost.
No weight saving / cost saving worth talking about, extremely inflexible for assemby in production unless using super fine wire (expensive production process )and the benefits you refer to in an electric motor are not really valid as a lot depends on the motor usage. Example, you drive your EV to work, 30 minute commute, car stands 8 hours then you drive home 30 minute commute, then your car stands in the garage for another 15 hours, no requirement for a perfomance / efficiency boost.
Maybe different if it was a commercial motor running 22 hours a day on a dock crane or conveyor belt system where high loads / usage is a factor.
One would have to run a comparison between the Copper plated Steel Wire over the Alumimium wire to see exactly what the difference would be in performance etc.
My guess the Copper / Alu will win out.

The best electrical conductor is Graphene.. even better than silver. However it is a 2 dimension material and does not conduct very well between layers. Not the cheapest by a long ways. Perhaps the future development will address these problems.