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Electric motor help

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ShawnR

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Hi all
I don't know if this is an appropriate question for an electronics forum but thought I would try. I know there is a wide range of talent and experience here.

I am trying to fix a squash ball machine for our junior program (like a tennis ball machine but just for squash balls). The machine is no longer supported by the manufacturer (sold by Black Knight) and the motor manufacturer has even gone out of business so data is hard to get. There are two motors that work together so I was able to get RPM off the good one. My question is if anyone would have suggestions in locating a replacement (or two ). I am hoping to luck into a direct replacement but I have spent some time on line and that is looking unlikely (although up until tonight, I was looking for an AC motor) . I am open to making minor physical changes, electronic ones if needed.....I would hate to write this machine off as it is a great asset for aspiring squash players.

The motor is about 5" long and 3" in diameter. It is labelled as 90 VAC, 60 Hz but is driven by a control circuit that varies the speed. (In typing this, I thought I should see what range the motor is driven in (volts) I found I measured the voltage as 51 volts to 115 VDC...so now I am more confused!)

The other motor spins in the opposite direction, although the same motor. Each direct drives a wheel about 6 inches in diameter and the squash ball is dropped between them, then fired to the court. I measured the maximum RPM on the working motor and it went up to about 3500 RPM and down to almost zero. I have not looked a the control circuit very much yet. It is working well, with the other motor.

Not sure if I am looking for an AC motor or a DC motor with this new info. Are AC motors ever driven with a DC voltage or is my DMM fooling me? On the AC scale, I got about 8 volts, regardless of speed input.

Anyone have any suggestions for me?
Thanks
Shawn
 

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dknguyen

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The motor is about 5" long and 3" in diameter. It is labelled as 90 VAC, 60 Hz but is driven by a control circuit that varies the speed. (In typing this, I thought I should see what range the motor is driven in (volts) I found I measured the voltage as 51 volts to 115 VDC...so now I am more confused!)
Where was this measured?

Not sure if I am looking for an AC motor or a DC motor with this new info. Are AC motors ever driven with a DC voltage or is my DMM fooling me?
A universal motor maybe? Can you see inside if it has brushes?
 
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rjenkinsgb

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The motor photo shows it says "Red Pos CCWSE" - it's DC, it is giving the polarity for the direction of rotation.

How many wires does the motor have and is there a total power consumption rating somewhere on the machine - that may give an idea of the motor power.

There are quite a few parameters to try and match up.

Edit - and what mounting style is it - side feet, end mount etc..
Can you give a photo of the complete motor?
 
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dknguyen

Well-Known Member
Most Helpful Member
The motor photo shows it says "Red Pos CCWSE" - it's DC, it is giving the polarity for the direction of rotation.

How many wires does the motor have and is there a total power consumption rating somewhere on the machine - that may give an idea of the motor power.

There are quite a few parameters to try and match up.

Edit - and what mounting style is it - side feet, end mount etc..
Can you give a photo of the complete motor?
What's the 60Hz label for?
 

ShawnR

Member
The voltage was measured at the circuit board connector, to the other motor, while running, no load. I am not at the ball machine to check total power but can add that later to this thread. In the motor, there are 16 bars or sections on the stator and commutator so 8 windings I assume? There are just two wires to the motor and the mount is the 2 screws protruding from the shaft end. They go through a plate. The feed wheels mount directly on the motor shaft.
When I first opened up the motor, I found several wires broken at the com. I went to the motor shop to ask about fixing them or general advice in going forward. He offered to fix it for me. After he looked at it, he said there were more serious issues with shorted and or open windings. In testing it now, iirc, there should be continuity to every other com connection? I find there is no consistency to the continuity checks so I see what he meant.....

Not sure if that makes sense. ...

Thanks.
 

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Les Jones

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In post #1 Shawn says "I found I measured the voltage as 51 volts to 115 VDC...so now I am more confused! " This makes me think it could be a permanent magnet motor. A question for shawn. Does the motor have stator windings or is the stator a permanent magnet ?

Les.
 

Les Jones

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If it is a universal motor i can't see the point of rectifying the AC supply, They could just use a phase angle speed controller. I agree the fact that the lable on the motor says 60 Hz would rule out a PM motor.

Les.
 

ShawnR

Member
There are permanent magnets on the inside of the housing, lining inside walls of housing. I thought the rotating part was the stator. ..wrong?
 

Les Jones

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No need for more photos at the moment. the magnets confirm what type of motor it is.

Les.
 

gophert

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There are permanent magnets on the inside of the housing, lining inside walls of housing. I thought the rotating part was the stator. ..wrong?
A stator is the stationary portion of an electric generator or motor, especially of an induction motor.
 

ShawnR

Member
How can I determine the horsepower rating for the motor I need without specs? I can measure current draw on the other one that is running..? I think that is about the only other electrical info I can gather that I can think of.

If you with more experience than I were working on this, what would you do here? ie what other options would I have? Switching to an AC motor? The control circuit gets a little more complicated but I did make a zero crossing triac controller last year that maybe I could convert or use the theory? Will stepper motors go this fast? That would be cool since I have only recently been successful with stepper motors but not sure if cost effective. I will try to get a photo up so that you can see better how this is used.

Any other suggestions? Anyone deal with this company? The specs on the link below are confusing. They do not match the title of the motor, ie RPM and voltage but the motor looks good if the title is more accurate than the actual specs page ie 90 vdc at 3500 rpm

http://www.electricmotorwholesale.c...00,90&attSearchList=,20027~2500-4000,20031~90

more specifically http://www.electricmotorwholesale.com/LEESON-M1110014/

Edit...I have found other suppliers this morning. Maybe just a matter of sending emails as nothing is jumping out as ideal.

Thanks

Shawn
 
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ShawnR

Member
More info...

No load, full speed current is about 280 mA. Loading it a bit easily runs over 2 amps.
Most of the time it would be running at the 280 at full speed. When a squash ball drops, I guess current draw would spike momentarily and then it would be a few seconds before another ball drops. I would think the inertia of the spinning wheels would take most of the power to deliver the ball but then a slight time lag to get the wheels back up to speed?

Shawn
 
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