50 Hz motor on 60 Hz

A 50 Hz motor will run fine on 60Hz power. A 1450 nominal motor will run at 1760 rpm when you go from 50 to 60Hz. A 50Hz motor has more copper than a 60Hz motor. Not all 60Hz motors handle 50Hz well, but the converse is OK. Good luck on that lathe, sounds great with a DRO and all, that's a pretty high-end feature.

GWE

Thanks. Original motor rating was 1720 so I guess it will run at 2064 which seems a little fast for a big motor, but if it has lasted this long, I guess it will likely continue.

This was eBay. I thought I paid a little more than I wanted because it was in driving distance and I could go and get it. Now that I am checking the lathe and all the extras that came with it, I think I got a very good buy. Didn't realize how much a DRO cost and the quick change tooling looks great too. If I had bought those features new, I got the lathe for free.

There is no such animal as a 50hz 1720 rpm induction motor. I suspect the rating plate has either been mis-stamped or misread. For a four pole motor, the 50hz synchronous speed is 1500 rpm. At 60hz, this becomes 1800 rpm. A two pole motor at 50hz is 3000 rpm, at 60hz this becomes 3600. Non synchronous motors run at a speed approx 5% slower due to magnetic slippage.

Chas sez:

Chas sez: " There is no such animal as a 50hz 1720 rpm induction motor. I suspect the

I suspect you misread Grant's reply. He said a 1450 rpm, 50 hz motor running on 60 hz would run at nominal 1760 rpm. That may be a little high, but you get the idea.

Bob Swinney

Get out your reading glasses and a good light and clean off that motor nameplate and have another look. It's entirely possible it may have nameplate specs for both frequency (50/60Hz) and rpm, and that you've picked up 50Hz from one and

If the original motor RPM was 1720, I suggest you clean the data plate on the motor off a little better and look at it with a magnifying glass. I suspect the 1720 is the RPM for 60 hertz.

Dan

After reading everyone's replies, I went and looked again. It's more ambiguous now. The power, voltage and Hz are stamped on the label but the rpm is printed. So it's probably a screw up in their labeling and the printed rpm value is for 60 Hz.

To complicate things more, the 5 in 50 could be interpreted as a 6. The bottom half isn't obviously open (as in 5) but the top half is square (as in 5). The voltage rating being at 240 seems to make it not a normal

Anyway, from what has been said, seems that it should work ok even if it is a 50 Hz motor. As far as I know it has been used in this area for quite a while, so I'll assume it will be ok.

Well, Chas explained the motor theory pretty clearly which I hadn't really thought about. So feeding it 60 Hz the rpm must be 17xx, maybe

So the rpm on the motor label must be for 60 Hz. I did find a different label on another part of the lathe that says it is for 50 Hz 240 V input. So apparently I did read the motor label correctly, just that the motor label gave the wrong rpm for what it is supposed to be.

A 50hz motor on 60 will just run fast, while a 60hz on 50 may overheat, as a 50hz device needs more iron.