Delta Induction Repulsion motor (NJ - VNA SALE - FAR HILLS)

Sorry If I got you excited . .

I was wandering thru the tools section of the Visiting Nurse Association rummage sale in Far Hills NJ today and came across a BIG Delta motor.

I was black with a DELTA INDUCTION REPULSION MOTOR plate. I think it said Frame 156 or something like that on the tag.

It had a piece of masking take on it marked WORKS, $15.00.

I don't know diddly about old motors but I figure someone local might be interested enough to swing by and look at it.

It's in the Tools area, within the Furniture enclosure, in the corner under the tables.

THe VNA Sale is free admission and runs thru Sunday. You might be able to bargain on the price.

Good Luck

Jim

Well worth that and there is demand, be it small, but a demand for those motors. Lots of torque from R/I motors.

Jeff Horton said:

Well worth that and there is demand, be it small, but a demand for those motors. Lots of torque from R/I motors.

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Jeff is correct, but the greater torque is only during startup. Once the motor is running, the torque is the same as any other electric motor of equal HP rating and equal operational RPM (like 3450 RPM).

HP is torque times angular velocity. So for two motors of equal rated speed and HP, the torque will be equal. Engineers have been able to calculate and measure HP and torque for a lot of years - and older motors were not built to generate higher than nameplate HP.

But RI motors do provide greater startup torque. Unfortunately, it's not of much use because we start our woodworking equipment without any significant load. That's the primary reason almost all single phase motors on woodworking equipment today is capacitor start.

Mike

I hope someone picked up that motor - hate to see it in a landfill.
I've got 6 R/I motors - three restored and in use, one earmarked for my lathe resto, and two on the sidelines waiting for an appropriate project. I like the old Baldor "Streamcooled" ones the best because they're totally enclosed. The Emerson running my 20" bandsaw is open frame - it has regular dates with compressed air and the shop vac. I haven't had the Delta drip proof open yet, but will this winter when i clean up that scroll saw.
One thing that's hard not to notice with R/I motors is their size and weight when compared to capacitor start motors. They have two sets of windings, which makes them bigger and heavier. The 1/3 hp on my Walker Turner 24" scroll saw is about the same size as the 2 hp capacitor motor on my table saw. The 2 hp saw awaiting a planer or big bandsaw resto is HUGE. I can barely lift the thing, and it definitely won't fit in any tight spaces. It's a total beast. The added weight can be a benefit if you're looking to smooth out some vibration. If you're moving your machines around a lot, it's definitely a hassle.

Paul Hubbman

Mike Henderson said:

But RI motors do provide greater startup torque. Unfortunately, it's not of much use because we start our woodworking equipment without any significant load.

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I'd have to disagree with a blanket statement mike. I can think of several applications were machines are started with a significant load; compressors, the real kind, not the way over inflated oiless junk. Bandsaws with real cast iron wheels, that's a lot of mass to get moving from a stop and exactly why it takes a bandsaw so long to wind up to full speed. Real planners and large jointers with large cutter heads.

Mike Henderson said:

That's the primary reason almost all single phase motors on woodworking equipment today is capacitor start.

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As long as we're speculating on why I/R motors lost favor, I'd say it has more to do with the cost of two separate sets of windings, the added cost of copper, increased weight and physical size.

Mike

M Toupin said:

I'd have to disagree with a blanket statement mike. I can think of several applications were machines are started with a significant load; compressors, the real kind, not the way over inflated oiless junk. Bandsaws with real cast iron wheels, that's a lot of mass to get moving from a stop and exactly why it takes a bandsaw so long to wind up to full speed. Real planners and large jointers with large cutter heads.



As long as we're speculating on why I/R motors lost favor, I'd say it has more to do with the cost of two separate sets of windings, the added cost of copper, increased weight and physical size.

Mike

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You're right, of course - blanket statements always have exceptions. It may be that the extra starting torque of an RI motor would be an advantage in certain applications. My guess as to why the capacitor start motor is used is because it's less expensive. Capacitor start motors are made in the millions while RI motors, while still made, are considered special application motors and are much more expensive. I expect they're also more expensive to make, primarily because of the brush and commutator elements. A capacitor start motor also has an extra winding - the starting winding* - and the iron mass required should be about the same in both cases (old motors are more massive because modern motor iron has better magnetic qualities than the iron used in old motors - of all kinds).

Additionally, by using only capacitor start motors, the manufacturers can reduce their inventory - both for original manufacturing and for spare parts stocking.

RI motors have brushes and that's a maintenance issue compared to regular capacitor start induction motors. Capacitor start motors have a centrifugal switch but those switches rarely need service - except in open frame motors in dirty conditions - but in dirty conditions, a sealed motor (like a TEFC) would be used.

My guess is that brush maintenance and cost were the major drivers towards capacitor start induction motors.

Note that all of this discussion only applies to single phase power - such as a residence or small industrial site. Any reasonable sized industrial site would have three phase power so RI or capacitor start would not apply.

Mike

*The extra winding on a capacitor start motor is in the stator, while the extra winding on an RI motor is in the rotor, but the material cost for the winding is probably about the same - ignoring the brush and commutator elements in the RI motor.]