Re: Miracle Motor

Well, my take on this is you are running a 260V motor on 80V or 70%
less voltage...If that isn't derating, i dont know what is...


Wally




--- In CAD_CAM_EDM_DRO@yahoogroups.com, Les Newell <lesnewell@h...>
wrote:

> Hi Wally,
>
> The big problem is heat. These motors are designed to be force air
> cooled. They will work without force air cooling but at a reduced
> output. You want the lowest winding resistance posible to reduce

the

> amount of heat generated. A motor that is designed for 260V is

likely to

> have considerably higher winding resistance than an equivalent one
> designed for 130V.
>
> The 2.5hp 130V motors may be twice the price but will work a lot
> better. I ended up using the 110V 1.5hp motors on my mill simply
> because they have a decent length of shaft sticking out the back to

fit

> an encoder on to. Item 10-1834 ($12.99) has a built in 200 line
> encoder that can be fitted on to these motors with a little bit of

work.

> With 2.3:1 reduction these motors will throw my Bridgeport around

at

> silly speeds.
>
> Les
>
> cnc_4_me wrote:
>
> >With the talk we have had lately about servo motors torque

remaining

> >constant ,and rpm being proportional to voltage. I expanded my
> >search for servo motors to include higher voltage motors I did not
> >consider before...The results are so startling I think they must

be

> >wrong.
> >
> >SPECS
> >Treadmill motor from surplus center item# 10-2167
> >2 ¼ HP at 260VDC
> >1 1/8 HP at 130VDC
> >95-260VDC
> >5 amps
> >0-5100RPM
> >
> >Calculated torque = 441 oz-in = 27.6 lb-in
> >
> >Assuming we are using an 80VDC supply. We are about 70% below

260VDC.

> >RPM at lower voltage = 5100RPM x .3 = 1530 RPM
> >1530 RPM / 2.5 pulley ratio = 612 RPM on screw
> >612 RPM x .2" lead = 122" rapids
> >
> >And now for the kicker...This motor has a max current of 5
> >amps...Our average current would be much less...And this is all at
> >27.6 lb-in x 2.5 = 60 lb-in torque at the screw... FROM A $10.00
> >motor...
> >
> >It just doesn't compute...
> >
> >Warning overload!!! Danger Will Robenson...
> >
> >
> >Wally
> >
> >
> >
> >
> >
> >
> >Addresses:
> >FAQ: http://www.ktmarketing.com/faq.html
> >FILES: http://groups.yahoo.com/group/CAD_CAM_EDM_DRO/files/
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