Old Roth Brothers and Company motor on a jewelry metal rolling machine.

[hbiss]

When did they start being able to use capacitors for motor starting? I don't think electrolytic capacitors were even available such as we know them much before the mid thirties.

So my thinking is that either this motor is much newer than the OP suggests, maybe the controller had a momentary "start" button that took the place of the centrifugal start switch or it is a repulsion/induction. I really don't think there is a capacitor in there but without a good look I can't be certain. It would be quite large. Open it up so we can see the back of the armature also.

-Hal

 

[ActionDave]

Shouldn't be any continuity from any lead to ground. So, yes that looks like a problem.

Your pictures are way too small to determine anything. How about some that are large and that show the motor from different angles?

That's not his fault, it's a function of the forum software. If you click on the thumbnail the pictures will get larger.

What you posted is mostly of the machine and you can hardly see the motor on the bottom.

-Hal

More photos from different angles of the motor on the machine is not going to give anyone any more of a clue how to hook up the leads on that motor.

 

[ActionDave]

Thanks for that, I'll attempt to file it in my head for future reference. So would this indicate that there is in fact a capacitor inside the motor casing?

I doubt there is a capcitor in there. You do need to get the motor off the machine and open it up and possibly trace out the leads, that would be the biggest help.

 

[hbiss]

That's not his fault, it's a function of the forum software. If you click on the thumbnail the pictures will get larger.

I know that and they are not nearly large enough! Really, posting images on this site is a problem!

More photos from different angles of the motor on the machine is not going to give anyone any more of a clue how to hook up the leads on that motor.

No, but I could see it's approximate age, if there was a compartment for a cap and possibly the armature end to see if there are brushes. That might give us a clue as to what kind of motor this is. He could certainly help by removing the end cover if there is one and posting a picture of the commutator/armature inside. That picture does nothing and neither does a picture of his chart of resistances.

-Hal

 

[LarryFine]

He should bring it to school so we all can see it.

 

[ActionDave]

I bet it's a repulsion induction motor and there is no cap.

 

[Brue]

He should bring it to school so we all can see it.

The year before high school I hauled a refrigerator motor/pump in a wagon to school. Used it as a replacement for a failed pump under a plate and bell jar. I hooked it all up with exposed knife switches and alligator clips nailed to a wood plank. We made dried deer jerky in it.

 

[Brue]

 

[Brue]

I doubt there is a capcitor in there. You do need to get the motor off the machine and open it up and possibly trace out the leads, that would be the biggest help.

with the owners agreement I'll open it up shortly after July 8.

 

[retirede]

I bet it's a repulsion induction motor and there is no cap.

I’d say that’s a good bet!

 

[iceworm]

The machine with all its gears weighs 800 pounds. The motor shop would charge to pull the motor out in order to open it up. And they may well damage the gears or their shafts in the process. So I may propose to the owner that I open it up in his shop and take a look expecting to find a centrifugal switch which might be repairable.

if this works do you have a method of sizing a capacitor?

My post was a physics guess. I'm out of my element concerning single phase motors. I wouldn't have a clue.

 

[iceworm]

I bet it's a repulsion induction motor and there is no cap.

I've never seen one - or didn't know it if I did.
So, my knowledge is way lacking - just pictures and physics descriptions in my dad's Audels motor book.

Aren't these brushed motors, internally shorted armatures, and would only have two leads?

(edit to add) Fat fingered the send button
What is the therory for the other leads?

 

[synchro]

When did they start being able to use capacitors for motor starting? I don't think electrolytic capacitors were even available such as we know them much before the mid thirties.

So my thinking is that either this motor is much newer than the OP suggests, maybe the controller had a momentary "start" button that took the place of the centrifugal start switch or it is a repulsion/induction. I really don't think there is a capacitor in there but without a good look I can't be certain. It would be quite large. Open it up so we can see the back of the armature also.

-Hal

It appears that capacitor start motors were first developed around 1925:

http://ece.umich.edu/bicentennial/chairs/bailey.html

They were quickly applied in refrigerators because of their high starting torque. It's not clear whether the application in the OP's post would require any especially high torque.

 

[hbiss]

I've never seen one - or didn't know it if I did.
So, my knowledge is way lacking - just pictures and physics descriptions in my dad's Audels motor book.

Aren't these brushed motors, internally shorted armatures, and would only have two leads?

(edit to add) Fat fingered the send button
What is the therory for the other leads?

Yes, unless it's dual voltage. Repulsion induction motors were used where you needed high starting torque like for a compressor. It accomplished that without capacitors so I suspect it predated the advent of capacitors for motor starting.

I don't think this machine requires an unusually high starting torque.

Food for thought, my parents had a rotary electric lawn mower back in the 50's. All it was was a 1/3Hp induction motor with a blade on it's shaft. Three wires up to the control panel on the handle. On the control panel there were two buttons. One you held down until it came up to speed and the other was off. Matter of fact it was the exact same two button switch that was used on many fluorescent desk lights of the day that didn't use a starter.

-Hal

 

[Brue]

It appears that capacitor start motors were first developed around 1925:

http://ece.umich.edu/bicentennial/chairs/bailey.html

They were quickly applied in refrigerators because of their high starting torque. It's not clear whether the application in the OP's post would require any especially high torque.

I have a book published in 1921 that talks of capacitor start single phase motors. But I suppose there were many patents on the subject so I'm not questioning the veracity of your link.

 

[Brue]

Yes, unless it's dual voltage. Repulsion induction motors were used where you needed high starting torque like for a compressor. It accomplished that without capacitors so I suspect it predated the advent of capacitors for motor starting.

I don't think this machine requires an unusually high starting torque.

Food for thought, my parents had a rotary electric lawn mower back in the 50's. All it was was a 1/3Hp induction motor with a blade on it's shaft. Three wires up to the control panel on the handle. On the control panel there were two buttons. One you held down until it came up to speed and the other was off. Matter of fact it was the exact same two button switch that was used on many fluorescent desk lights of the day that didn't use a starter.

-Hal

Here's a diagram for a repulsion induction motor out od a 1921 book on electrical machinery. It shows two leads and interestingly a normally open centrifugal switch.
However, I don't see a way to wire my leads to achieve this diagram. Wouldn't a test from a to b show a short circuit in an unconnected motor?

 

[Brue]

Here's a diagram for a repulsion induction motor out od a 1921 book on electrical machinery. It shows two leads and interestingly a normally open centrifugal switch.
However, I don't see a way to wire my leads to achieve this diagram. Wouldn't a test from a to b show a short circuit in an unconnected motor?

I can see a need for this machine to be reversible to back out of a situation the machine could not handle. However, one could accomplish removing a partially completed rolling operation by backing off the separation between rollers without reversing the motor.

 

[Brue]

Here is what I expect to verify and fix when I open this motor up. The ohmic values are what I found in my ohmic mappings of my randomly numbered motor leads. The right hand portion of the diagram is my proposed motor wire connections. The two double ended arrows indicates a movable set of brushes which I saw evidence of on the back end of the motor even though the motor is nearly totally enclosed. Solid lines being internal connections and dotted lines being external conditions.