Working around motor

I work around motor that are 440 3phase, how far away should i be from them running and they are grounded



by AgentX86 - 2022-12-12 21:51:18

Actually, other than being larger, three-phase motors are less dangerous than single phase because the phases cancel at a distance.

Anyway, if this isn't a monster motor, like 100HP, it's likely no problem as long as you don't hug it.  Larger, and it's probably a good idea to avoid it if possible.

Small motors are no problem at all. It's 440 three-phase so it's not a small motor.  I'd err on the safe side, if possible.  I'd try to stay a few feet away from it. If you feel strange, move further away.


by Tracey_E - 2022-12-13 09:14:53

We should stay 6" away from anything questionable, so as Agent said, just don't hug it. 


by Good Dog - 2022-12-13 16:17:49

I worked very closely around both synchronous and induction motors from .5 hp to 4,000 hp and from 440V to 11,000V throughout much of my career. I also once stood within 6" of an operating turbine generator at the Niagara Falls Power Plant. I am not recommending it, but I never had an issue. As the folks indicated in the two previous comments, it is probably not a good idea to hug a motor. The 6" rule-of-thumb is a good one!  

dont hug it

by dwelch - 2022-12-29 13:46:34

If you can find a nice/real gauss meter (not the $20 things), rent one from a metrology company or have them come visit.  Now this was 20 years ago but 1.5 I think was the magic number for that medtronic at that time.  We had a shake table with a big transformer that would make the analog computer monitors at the time change colors at a distance.  Turns out I would have to literally hug the thing while operating, it was a few inches.  Thus the 6" blanket rule folks talk about.   

The field energy drops like the surface of a spere so it is one over distance squared,   2 inches is 4 times less than 1 inch, 3 is 9 times less 4 16 times less.  And so on, feet away it is very week.   It has to be so strong as to confuse the device, am I reading the electrical signals of the human or the induced frequency of the emi?  And then the device may simply stop, while in the field as it does not know what to do, if you pass out or feel weird and otherwise move away, then it goes right back to pacing.   

Easy answer, dont hug it while operating, which is more likely to harm you mechanically not from a pacer perspective if you did that anyway.  (fingers and noses getting into gears and shafts)

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