[DerekZahn]

I believe that is correct. That 1 kW motor would turn into a 500 watt motor if you run it at 50v. At 50v the "rated" torque should not decrease Eventually if you lower the voltage enough you won't be able to get even the rated torque. This is because the "peak" torque does decrease if you decrease the voltage, since the motor will not be able to draw as much current at the lower voltage and torque is proportional to current.

I think the biggest downside is that they 1 kW motors are kind of bulky.

I have some of the 300w motors. Because I got some cheapish brushless drives off of ebay that cannot go up to 100 volts, I plan to run the motors at 60-70 volts (depending on what power supply components I can scrounge). That will turn them into 200w or so motors, but that should be plenty for my needs.

[Al_The_Man]

This is another site that offers some detailed specs on Sanyo Denki P5 & P3 motors, although it only shows chart up to 700w. www.netmotion.com
It seems to confirm that they will run up to 4500rpm, which I would have expected in an AC servo, the 3000rpm seems on the conservative side.
One of the biggest effect on sizing is the effect of the weight or force of the load on the inertia matching of motor to load when accelerating.
The ideal is 1:1 but some sizing programs will allow a match up to 10:1, fortunately the reflected inertia of the load decreases by the square of the reduction ratio.
Having a high rpm motor and high reduction ratios allows the use of smaller motors, hence smaller supplies.
One conflicting statement on their web site is to size the power supply for all motors at peak torque, where other sites like A-M-C recommend a de-rating factor.
Al.

[DerekZahn]

That netmotion.com page about the P5 motors is interesting. To my eye it appears that the version of the P5 they have in their tables is designed to run at higher voltage than the versions on surplus center.

Hmm, inertia calculations eh? My eyes sort of glaze over when I see units like kg*m^2(GD^2/4). Anybody have an example of an intertia calculation?

[DerekZahn]

Hmm, this inertia stuff is kind of interesting, something new to learn!

Here's a little paper for the theoretically inclined:

http://www.motionvillage.com/welcome...es/Inertia.PDF

[Al_The_Man]

Hmm, this inertia stuff is kind of interesting, something new to learn!
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There are quite a few sites that offer free graphical sizing programs, Allen-Bradley, Kollmorgen, the one on the Sanyo-Denki site, you have to phone a 1-800 #, I haven't tried that one. There are others, I use them mainly to see if I am in the ball-park for sizing.
At one time (before the web became popular) many manufacturers put out catalogues that also contained rafts of engineering/sizing info. I fortunately held on to mine, also usefull for identifiying older motors. :banana:
Al.

[Builder4wd]

Gentlemen,

I received my 2 surplus ctr motors on Monday, and A DATA sheet too! I looked it all over, and also forwarded it to Vladimir for his review. .......

Tom Eldredge
Rutex LLC

Did Surpluscenter include a datasheet with the motors? I bought 3 of those 300W motors, but they didn't include a data sheet for me. Do you have a scan of the data sheet?

Thanks!