Electric Motor hook up

Don T

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Okay I am taking my time setting up my Heavy 10. I have been reading tones of info. One of the things I see talked about is the use of a VFD with motors. I am just wondering why a lot of you guys don't just buy a 1hp or what ever you need in 220v? Also my motor can run on 110 or 220. Which is better? I can hook mine up to 110 and use a variac in line and get just about any speed I want. Has anyone done that? The variac I have goes to 150v and is a 33 amp model.
 

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I've heard a lot about 220 being the best, but I've never used it. I've survived on a 3/4HP "Junior" for some time, though I would love to upgrade to a VFD. VFD seem to have a much better efficiency than straight AC hook ups. AC motors require a start capacitor when connected if I recall in order to run like that. It is very inefficient, but it still works.

The problem with 220 vs 110 is that most people have to wire a 220 to get it. Garages for the amateur typically do not have 220 wired in. That can be considered yet-another-cost when thinking about what you want. 110 is simple, easy, and less costly to get in at the ground floor and that makes it a prime entry point for amateurs like me.
 
There is only one advantage to 220V, that is the wire size can be smaller than for 110V; there is no difference in power. If you have a 3 phase motor, then a frequency drive is a good thing, as it gives you true 3 phase power and the capability of speed control and instant reverse. A variac will not work with an normal AC motor for speed control, they only work on brush type universal AC/DC motors. I fail to see the need for speed control on small lathes such as your SB, the usable speed range for freq. drives is not very broad especially at the low end due to loss of torque. If you are running a motor on whatever machine, up to about 1 HP, the amperage it is easily possible to use 110V, as the amperage draw is only about 11 amps.
 
A Variac will not control the speed of a capacitor start single phase AC induction motor. The speed is controlled by frequency not voltage. Induction motors like the one you show are designed to operate at one speed. If they slow down too much the centrifugal starting switch will close and the start winding will engage. The start winding is only designed to operate for a short period of time. If engaged for long periods (like a failed starting switch) the start winding will overheat and burn out. 3 phase motors do not have starting windings, VFD's change both voltage and frequency allowing speed change. The better VFD's also monitor feedback from the motor which allows them to adjust the power supplied to maintain constant speed under varying load.
 
Thanks. That is what I needed to know. Wiring 220 is easy for me, I even already have the correct wire needed so that is how I will go. Thanks again.
 
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