AC repulsion-induction electric motor 1

[grannyknot1]

Hi Guys, first post so I hope I'm in the right forum,
I have a very old Leland Electric 1/3hp single phase, repulsion induction motor with a forward/reverse lever that also allows variable speed from 500 rpm to 2800 rpm. I have actually got the motor down to 100rpm and it seems fine at that speed, I would like to use to power a 14" band saw using the high speed for wood and lowest speed to cut metal.
Does that sound like a use that a motor like this could handle?
Again sorry if this is the wrong forum,
thanks,
Chris

 

[electricpete]

I had to google repulsion motor

https://en.wikipedia.org/wiki/Repulsion_motor

It's a strange beast

In repulsion motors the stator windings are connected directly to the AC power supply and the rotor is connected to a commutator and brush assembly, similar to that of a direct current (DC) motor.... there is no electrical connection between the two and the rotor current is generated by induction. The rotor winding is connected to a commutator which is in contact with a short-circuited pair of brushes which can be moved to change their angular position relative to an imaginary line drawn through the axis of the stator. The motor can be started, stopped and reversed, and the speed can be varied, simply by changing the angular position of the brushes.

=====================================
(2B)+(2B)' ?

 

[waross]

Just when I think that I have seen it all, something new.
I have worked on a couple of Repulsion-Induction motors, but the last time I saw one was in 1983.
I have never seen one with brush shifting gear such as that one.
The more common induction-repulsion motors started as a repulsion motor by virtue of the brush gear.
When up to speed, a centrifugal mechanism shorted the commutator and lifted the brush gear, and the motor ran as an induction motor.
My impression of these motors was;
"Tougher than a hammer."
I found a repulsion-induction motor belt driving a refrigeration compressor. The vee belt was introducing too much friction so that the motor did not have enough torque to run as an induction motor.
The belt was found running very loosely.
The belt was tightened, BUT.-
The belt and sheaves were worn badly and the tightened belt was running too deep in the sheaves and too much side friction was developed.
The motor would accelerate as a repulsion motor until it transitioned to an induction motor.
As an induction motor it did not have adequate torque and would slow down until the centrifugal mechanism transitioned back to repulsion mode.
It would go through a cycle in several seconds.
Any modern single phase induction motor that was overloaded and cycling on the start winding would be expected to burn up in a time measured in minutes.
This one had been running that way for a few days.
The motor was warm but nowhere near burnout temperature.
The drive belt was loosened and the motor then ran normally in induction mode.
The people who made it may have known what they were doing. I would avoid running the motor below rated speed.
Question: Does this motor have the commutator shorting and brush lifting gear for transitioning to an induction motor at high
speed?
As I said; Compared to a "U" frame motor, those motors were as tough as a hammer. Compared to a "T"frame motor, those motors were tougher than a hammer.
An interesting observation:
In Canada today, standard motor voltages are multiples of 115 Volts and standard system voltages are multiples of 120 Volts.
That motor was made when the standard motor voltages were multiples of 110 Volts. That motor is likely over 70 years old.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[grannyknot1]

waross, there is no brush lifting gear, just 4 brushes in continuous contact. Pull the lever to the center and the motor stops, move the lever from one side to the other, forward to reverse and the motor come to a brief stop in the middle and spins up to 2800rpm, it's quite amazing.
I'll try and take a pic in the dark, there are sparks coming off of all 4 contacts.

 

[waross]

Unique. Thanks for sharing this with us.
That is a motor that I have never even read about much less seen.
By sure to make sure that the bearings are well lubricated.
It would be a shame if that motor failed due to bearing failure.

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[grannyknot1]

Yes it is well lubed, I recharged internal felt of the bronze bushing with 75/90 gear oil.

 

[itsmoked]

We had a 3HP repulsion motor that ran our shop air compressor. It had been scavenged out of refrigeration service. It was a beast. I believe they were generally used out in rural areas where the line voltage was soggy. We used it in 120V service with the return thru a piece of 1" conduit driven in the ground.

I think that qualified as a soggy rural supply.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[dArsonval]

Various types of "repulsion" motors have long been confused with one another.

Noting that most saws typically start without a load, this motor would likely serve greater where its high starting torque attribute would be better utilized.
Prohibiting debris from saw chips getting into the motor while providing adequate airflow and access to the brush shifting lever will obviously also be required.

I get a kick out of the frame numbers on these old motors.

As shown in one of the OP's photos, what is a 35A frame?

It be similar to inquiring, "What is a RS 1-1/2 Frame?"

I'd say the OP's Leland motor is too fancy for a saw.

John

 

[waross]

Thanks Jon.
That text book does not agree completely with direct field observations and experience.
There is a break in the speed torque curve, and the torque when running as an induction motor is less than the torque when running as a repulsion motor.
While brush noise may be continuous in a brush shifting repulsion-induction motor, in may motors the brushes are lifted from the commutator at running speed, and the motor runs at synchronous speed less slip.
The text does make a distinction between a repulsion start-induction run motor and a repulsion motor.
The nameplate notwithstanding, I would consider the motor under discussion a repulsion motor, not a repulsion-induction motor.
--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[FacEngrPE]

I remember Audels Electric Library has an extensive discussion on repulsion motors.

I think this torque curve (the type without a brush lifter) is what is being discussed above:

There are some additional illustrations that show the action of shifting the brushes.

The only time I saw one was in a church pipe organ, about 1979. The pipe organ has been salvaged from a church that was demolished about 1970, the organ was thought to have been built in the 1920's. It was a single phase motor that drove the blower and a 74 volt generator. The commutator working surface was flat having wedge shaped bars and brushes that were also wedge shaped, The brush lifter moved the brushes along the motor's shaft axis, under the command of s flyball mechanism.
The motor was replaced when we needed to replace the brushes, as we could not find a source for wedge shaped brushes.