What's new
What's new

3 hs in need of a stator

drylakemachine

Hot Rolled
Joined
May 22, 2008
Location
elmirage ca
I didn't get any hit's in the for sale forum on my 3hs, so It's now down to sub assembly. The way's and gearing all look ok.
The reason for getting rid of it, 1 no panel with it 2 15-30 hp motor at 3600-7200 rpm. 3 all the wiring to the stator cracked and frayed.
Would replacing the 1500 rpm motor w/ a 1750 rpm motor in the knee work.
I might just clean everything up and put it back together, will need to figure out how to mount a cutting head in place of that high speed thing.
 
I didn't get any hit's in the for sale forum on my 3hs, so It's now down to sub assembly. The way's and gearing all look ok.
The reason for getting rid of it, 1 no panel with it 2 15-30 hp motor at 3600-7200 rpm. 3 all the wiring to the stator cracked and frayed.
Would replacing the 1500 rpm motor w/ a 1750 rpm motor in the knee work.
I might just clean everything up and put it back together, will need to figure out how to mount a cutting head in place of that high speed thing.

Check the dataplate. Is that 1500 RPM even @ 60 Hz?

Or @ 50 Hz?

It may already have been running at 1750 RPM for Donkey's Years.

In any case, I don't think it cares if it gets 1150 +/- or 1750 +/- for a replacement.

Things just move a tad slower or faster. BFD. It ain't a railway station clock.
 
If it's just cracked lead insulation, take it to a motor shop and have them re-lead it for you. Shouldn't cost much at all. Windings are very likely fine. 3ph motors are pretty much bullet proof, as long at they aren't over heated.

As for speed, there is no 1500rpm 60 cycle motor. You can make one with 6 poles (1200rpm), 4 poles (1800rpm) or 2 poles (3600rpm) at 60hz, that's mathematics. The rest of the speeds are with the required slip between the coil inductive rotation and the rotor at full load, 1125, 1750 and 3450 rpm. Put a 1750 rpm on it. I would never overspeed a gearbox without knowing if it can handle higher speeds as documented by the maker. Underspeed is fine, just have to check and accomodate the changed feed rates when calculating chiploads.
 
For what's its worth, and having not seen your motors windings if its just the insolation breaking down on the leads and nothing more get some good 3m or equivalent heat shrink tubing rated for 300 volts or more and slide them over the old leads insolation up to the winding them self's cut to length needed.
And apply a little heat from a heat gun/hair drier and shrink them to the leads. We did this on a couple of old open frame motors with cloth insolation a few years ago worked great. Both motors still up and running.........
I know it seems everyone's going ape shit over VFDs, these old K&T motors winding don't really like them that much,.
If you change to a later motor that is compatible to VFDs or inverter duty then great.
 
OP just raised a query in another thread that is better dealt with here, as the background matters.

Question had to do with how the 3600/7200 RPM 2-speed motor ref above and by John as what I take as a direct-drive spindle power could be two-speed with but 3 wires.

Shall we surmise that the far-end of those 3 wires is/was set up for either of Delta or Wye selection?

Or?
 
Shall we surmise that the far-end of those 3 wires is/was set up for either of Delta or Wye selection?

Or?

not only that but each of the 6 wires that feed into the motor connect to two coils.

here are some diagrams
http://www.practicalmachinist.com/v...motor-switch-help-please-steinel-mill-314966/

note that there are two ways to connect the coils, delta and wye.

some motors are delta for one speed and wye for the other. others are wye for both. pumps which are a quadratic torque load are wound such that the low speed has effectively half the magnetic flux (edit: actually, 1/1.73), a third of the torque. this would be 1/5th the hp.

so that is one of the reasons you find two different diagrams for two speed motors.

an example of a two speed pump motor nameplate is in post #15, half way down the first page.
AC motor 1st time running, strange vibrations - The Australian Electric Vehicle Asn - Page 1
 
not only that but each of the 6 wires that feed into the motor connect to two coils.

here are some diagrams
http://www.practicalmachinist.com/v...motor-switch-help-please-steinel-mill-314966/

note that there are two ways to connect the coils, delta and wye.

some motors are delta for one speed and wye for the other. others are wye for both. pumps which are a quadratic torque load are wound such that the low speed has effectively half the magnetic flux (edit: actually, 1/1.73), a third of the torque. this would be 1/5th the hp.

so that is one of the reasons you find two different diagrams for two speed motors.

an example of a two speed pump motor nameplate is in post #15, half way down the first page.
AC motor 1st time running, strange vibrations - The Australian Electric Vehicle Asn - Page 1

I think the question was not about how a motor is built to OWN two speeds.

Rather how the reconfiguration was made to happen to tell it which of them to use when only the THREE wires left the motor to the outside world power and control station.

Possibilities seem scant:

- Electrician on standby as an 'Operating Engineer' who locked-out power, climbed a ladder, re-terminated inside the peckerhead/motor casing, climbed down his ladder, powered back up.

- Only one speed was selected by a board meeting of company Directors, hard-wired, then used for months or years with no change

- Magic was applied at the control box to send two different flavours of juice down the three wires..

Or ..... A prior owner re-wired with only three wires because they only wanted the one speed.

Not really a mystery. We just aren't looking at the original wiring scheme.

I'm betting on the last one, BTW.

:D
 








 
Back
Top