Can anyone tell me the RPM of this motor?
[OP]
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Can anyone tell me the RPM of this motor?
Last edited by Lee Schierer; 03-15-2018 at 7:58 PM. Reason: fixed photo orientation
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The nameplate says 2900RPM at what is almost certainly 50Hz although that's a bit hard to read. So it's a two pole motor and you can expect a bit less than 3600RPM at 60Hz and full load.Originally Posted by Marc Coogan
Beranek's Law:
It has been remarked that if one selects his own components, builds his own enclosure, and is convinced he has made a wise choice of design, then his own loudspeaker sounds better to him than does anyone else's loudspeaker. In this case, the frequency response of the loudspeaker seems to play only a minor part in forming a person's opinion.
L.L. Beranek, Acoustics (McGraw-Hill, New York, 1954), p.208.
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David is correct about the RPM, but this is a 3-phase motor designed for 50Hz. It's configurable for delta or wye input, depending on the service.
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For next time, the secret is that a number raised to the power of -1 (negative 1) equals 1 over that number. The 'number' in this case is 'minutes', so 2900 * min^(-1) = 2900/min. Seems like our Euro-bros just imply the 'revolutions' part....
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What else would a motor do?Seems like our Euro-bros just imply the 'revolutions' part...
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Some rotate. Some translate (linear motors).What else would a motor do?
Moderator
Maybe it will help in the future: if a motor is running a cheap way to measure the RPM is with something like this:
https://www.amazon.com/gp/product/B004Q8L894
I've used this for several tests and to calibrate a speed control. You just attach a small piece of reflective tape to something that turns and point the tachometer towards it.
JKJ
Contributor
2900 min-1means 2900/min (rpm)
Member
It depends on the line frequency of the power supply. It's a typical European delta-wye 2 pole 3 phase motor so it will run at something a little less than 3000 rpm on its "native" 50 Hz supply (the maker quotes 2900 rpm) and a little less than 3600 rpm (~3450 rpm or so) on U.S. 60 Hz 3-phase current.3 phase motors have a reasonably wide range of acceptable operating frequencies/speeds so unless the piece of equipment is something where a cutterhead is near its limit speed with the motor running at 50 Hz, you can run at on 60 Hz without issues.
Last edited by Phillip Gregory; 03-15-2018 at 10:34 PM.
[OP]
Member
This is the motor on my new tablesaw. Thanks for the help guys. I ordered a static phase converter for it I was just thinking I would keep my eyes open for a cheap 5hp single phase down the road.
[OP]
Member
I looked into a Vfd for it but it was in the neighborhood of 800.
Member
As long as the blade isn't spinning any faster than 15,800 fpm tip speed at its factory-rated 50 Hz, you will be fine running the saw on 60 Hz with a phase converter. Do note that delta-wound motors have to be derated by a full 50% on a static converter vs. 33% for wye-wound motors- I am assuming you're running it on 240 volts and you are not backfeeding a 277-480Y transformer with 240 volts to get 416 volts output and feeding that to the motor wired on its high voltage setting.
Contributor
I've owned a bunch of Italian motors and most run hot at 60 hz. I'd pay attention to how it handles the static which may heat it up some more. I would also expect the bearings to need replacement if the motor is over 15 years old. I've had dozens of used motors but the only ones I've had fail are the Euro 20 year old ones. Not saying it will have problems, but I would check it out after running 10-15 minutes. Dave
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Nearly all motor bearings are inexpensive, I typically replace them unless the machine is new or close to it.
Most anything Italian is going to be nice/high end and pricey. I'd personally go with the VFD even if it costs $800 just to get the correct speed and full power out of the motor on a nice/high end/pricey piece of equipment. The OP mentioned trying to get a 5 hp single phase motor for the unit, that may be tough as European motors are IEC rather than NEMA frame size and IEC motors aren't common this side of the Atlantic. Regal (Marathon) does sell IEC pattern motors but they're pricier than a 7 1/2 hp VFD.
Contributor
At least it looks like a 112 frame motor. Euro machines are notorious for putting lots of wire into a small frame motor to boost hp and save weight- and cheat a little on the build. Dave
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