50 Hz motor on 60 Hz
 

xray wrote:

I just picked up my first metal lathe. It was originally sold by Warco,
a British company, but is a Taiwanese lathe. Made in 1987, it looked
pretty dirty, but as I am cleaning and lubing it, it looks pretty good
with no major wear. Seems much better than other Chinese lathes I have
seen in stores and has nice features -- DTM tool post, Sargon DRO, and
built-in coolant pump.

So after I cleaned the label on the motor enough to read, I found it is
actually a 50 Hz 240 V 1 Hp motor. As far as I know, it has been
working fine in California on 60 Hz 220 V power. Should I be concerned
about the motor at all? Other than the rated speed being a little off
might there be any problems.

I haven't even tried to power it up myself yet. Focusing on cleaning
years of accumulated dirt and ensuring everything is lubed and free
moving. Cleared up a couple of minor issues but it all looks pretty good
so far.


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

"xray" wrote in message
...
On Tue, 14 Jun 2005 00:25:07 -0700, Grant Erwin
wrote:

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.

SNIP
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.
--
Regards, Chas.


To Email, replace 'xxx' with tango papa golf.

Chas sez:

Chas sez: " 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."

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





"Chas" wrote in message
...

"xray" wrote in message
...
On Tue, 14 Jun 2005 00:25:07 -0700, Grant Erwin
wrote:

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.

SNIP
--
Regards, Chas.


To Email, replace 'xxx' with tango papa golf.

xray wrote:

On Tue, 14 Jun 2005 00:25:07 -0700, Grant Erwin
wrote:


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.

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
1720 rpm from the other. 1720 is what it will run on 60Hz power, not 50. - GWE

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

Sooo...

Power it up.. take a tach read and tell us what it really turned out to be
:-)


Dave

"xray" wrote in message
...
On 14 Jun 2005 08:14:40 -0700, "
wrote:

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
60 Hz motor so I assume it is 50 Hz.

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.

On Thu, 16 Jun 2005 03:38:16 GMT, "Dave August"
wrote:

Sooo...

Power it up.. take a tach read and tell us what it really turned out to be
:-)


Dave

"xray" wrote in message
.. .
On 14 Jun 2005 08:14:40 -0700, "
wrote:

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
60 Hz motor so I assume it is 50 Hz.

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.


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