Motor Efficiency

Hi Don.

In my opinion, you need to plot a load line with a torque speed curve, and that can give you better answer, as there may be very much possibility that both are better than one another but at different speed.

Its difficult to set a thumb rule as design of motor is also equally important, what consideration had been taken during the design of motors?

very small AC induction motors have efficiency ranging in 10 to 15% at the same time you can have bigger sizes with 95% efficiency.

For the different Hp vs torque I took the path of a 1/4 Hp motor & 1/2 Hp VFD for overdrive speed. The three phase motor had a 72% efficiency, and I'm sure driving it down at such a low speed; "in the weeds," so to speak, will put the efficiency of the entire system fairly low, but inherently, how do steppers compare? The one my colleague wanted to use was a similar torque output 24 VDC gearmotor. My thought was: think of the I²R losses at such a low voltage!! So who's right?

Thanks,

Don

When it came time to choose a twin axis drive environment for a large aperture fork mounted scope, I went with Pittman geared motors and integrated encoders managed by a Sidereal Technology microprocessor based electronics.

I did not want to deal with the periodic error common to worm drives so I chose instead to use a hardened steel ring gear and steel pinion; a simple steel on steel friction drive for the right ascension drive

I have more concern for effectiveness than efficiency. The power consumption difference between the Pittman motors and the equivalent steppers is not enough to be concerned about.

You did not say how heavy your system is but I can't imagine this response being significantly different even for a very heavy mount.

L.J.