Fantastic post with numbers !
(Timing) Belt drives are about 96-96% efficient.
Marine gears are about 80% efficient.
Thats why marine gears have oil coolers. The losses are heat.
Thats why belt drives dont get hot. Very little losses.
Re: electric motor drives.
I also advocate using industrial motors for propulsion.
If I get time, I may setup something myself.
Industrial motors are much more efficient than the typical cheapish
controllers.
These would be known as servo drives. A 3-phase VFD is similar, but less
sophisticated.
Prices have dropped 50-80% in the last 5 years.
A servo drive produces almost no heat - and is very very efficient.
I believe its similar to the 80% vs 96% situation.
They also last essentially forever (totally digital) as they are meant
to run 24x7 in hot, humid conditions inside a milling machine for example.
Ie continuous duty.
Typical service interval (replacement) is 10 years, at 24x7 use.
An AC brushless servo is cheap.
I use ones I import. A 2.5 kW 220V system is about 800€ tax (22% VAT,
import, freight) paid in the EU.
Motor, encoder, controller, cables.
This is so everyone knows a price-point.
All sizes exist, to 100 kW and up.
I use 400W (80V), 750 W, and 2.5 kW, (220V), for now.
Industrial use drives must run reliably, much more so than most consumer
stuff.
As a consequence, the sota is such that they all simply work,
essentially forever.
My old Bridgeport 3-phase motor still runs fine. (Silent.Powerful
Continuous duty).
Built circa 1950, or 60 years ago. I run it with a VFD.
Now changing to an ac brushless serco.
--
-hanermo (cnc designs)
Posted by: Hannu Venermo <gcode.fi@gmail.com>
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