Now that my utility is calling Cu a "precious metal" in its anti-wire theft campaign what is the status of Al wound motor development?
Supposedly the WWII era Al motors burned up easily but there shouldn't be any reason why they couldn't be protected very cheaply nowdays.
If a motor costs several cents/watt and develops 1 W/gm a motor and the cost of copper is 1 cent/gm maybe a third of the cost is copper.
Bret Cahill
Aluminum wire requires different connectors than copper. It expands and contracts more with temperature changes. Check with the EEs over at alt.engineering.electrical. They could give you a definitive answer.
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than copper. ?It
Al also melts a much lower temperature but these issues might all be resolved with proper design and controls.
At least one killer is the conductivity of Al is 30% less than Cu which means the coils in an aluminum motor wouldn't pack as tight for the same current & field and the motor wouldn't be as efficient as copper. Since the cost of electricity over the lifetime of a motor might be an order of magnitude more than the motor itself, the 30% increase in capital cost of a Cu motor over Al can be justified with only a 1 or 2% efficiency increase.
Copper probably can provide that efficiency increase.
OK.
I'll also ask about those "pegleg" transmission line towers that have one wood pole leg and one steel with a wood pole running across the top.
Bret Cahill
Perhaps silver could be justified in this application.
What application? Swindling the ignorant?
A 5% increase in conductivity won't result in anywhere near a 5% efficiency increase, certainly not enough to make up for an order of magnitude or so higher capital cost.
Maybe there is some really coincidencial situation where the only motor that will work must be slightly smaller that what is possible with Cu.
But that's a small market.
Bret Cahill
Al also melts a much lower temperature but these issues might all be resolved with proper design and controls.
At least one killer is the conductivity of Al is 30% less than Cu which means the coils in an aluminum motor wouldn't pack as tight for the same current & field and the motor wouldn't be as efficient as copper. Since the cost of electricity over the lifetime of a motor might be an order of magnitude more than the motor itself, the 30% increase in capital cost of a Cu motor over Al can be justified with only a 1 or 2% efficiency increase.
Copper probably can provide that efficiency increase.
OK.
I'll also ask about those "pegleg" transmission line towers that have one wood pole leg and one steel with a wood pole running across the top.
Bret Cahill
Using aluminum, larger conductors to keep the same resistance means that the motor becomes larger. This affects core losses and to counter that means more turns. In addition, the motor would have to run a bit cooler -this also adds to the size problem. It all comes down to a balance between the performance (including efficiency) and costs. going to aluminum may be OK in some cases but the overall savings may not be there. It would require a hard nosed analysis of all the factors. I expect that manufacturers have already explored this option considering today's copper prices.
With transmission lines it is easier- wrap the aluminum around a steel core and go with it- this was recognized in the late 1930's.
I've not seen the "pegleg" construction but I suspect that either the steel tower or the wood tower was there earlier and it was the cheapest alternative when upgrading transmission capacity to simply add the other tower and the crossbar to get the needed spacing between phases at a higher voltage. --
Don Kelly snipped-for-privacy@shawcross.ca remove the X to answer
It might not even be lighter than a Cu motor, Al's only major selling point besides being a somewhat less desirable target for thieves.
If the cost of electricity went way down then Al might make sense.
If it were close they would be fine tuning their spreadsheets.
Sounds plausible. No one here would waste much time sourcing a matching pole just for aesthetics. Add the cheapest support and call it a day.
Maybe they could save some ground wire with the metal poles.
Bret Cahill
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