Slo-Syn TS25-1024 "stepper motor" info?

[J Tiers]

I have one of these that I do have a use for. But if it is a stepper motor, it seems odd compared to most. Did not find anything useful on line, and am not sure what sort of driver it wants.

It has 3 wires, but I cannot find a combination that will actually step. It feels like a stepper, as it has many very fine "coggy" positions when rotated by hand. However, most combination result in a very strong step in a direction, followed by a not quite as strong step in the opposite direction, when the other wire is energized.

Is this not what I think?

[MaxHeadRoom]

That appears to be one of the older AC sysnchronous motor versions, it has three conductors and requires a R/C set up to run synchronously on AC mains supply.
The TS stands for 200rpm version when ran on 60Hz.
SS = 72 rpm
LS = 28.8 rpm
They are connected the same way as a asynchronous PSC AC motor.
They are intended to be ran on simple AC supply with 'instant' stop/start and can be stalled with no problem.

[J Tiers]

For what then is it called a stepper? Because it is so called, and it has rotation like a stepper. Clearly has magnets in it, a compass goes crazy near it, and rotation is coggy exactly like every stepper motor.

The "steps per rev" is blank, but..........

As a synchronous motor, it would need to be started, but then would need no more assist. I doubt it has any amortisseur windings 😉 in that small case, so perhaps a start cap that could be ignored during running.

Evidently available as either? Surely they could afford a label for a synchronous motor if they needed one. It is a puzzlement of sorts as to why it is not simply described on it's data plate as what it is.

[MaxHeadRoom]

Because that is how it is shown in the Superior Electric Design Engineers Guide to AC synchronous motors - DC stepping motors as such.
It is constructed fairly much the same as its DC stepper counter-part. Superior describe it as a SLO-SYN motor.
The stator has 8 salient poles & 2phase, 4 pole winding's
It can be fed from a 2 phase source or the 1ph with the R/C to one winding, it can also be fed with DC to increase the holding torque when stationary, in some applications.
If you were to disassemble it, it appears identical to a typical DC stepper.
I have come across them a few times in the past when used for fixed RPM reel feeders etc. No sophisticated driver needed if one speed is all that is needed.
As a synchronous motor, no other starting arrangement needed?
Disconnect the Cap and it will stall
They do describe it for what it is, just read the data plate!

[nickel-city-fab]

FWIW, these were common on larger aircraft back in the day. Used to control hydraulics etc. Also used for process control valves etc. Its one of those odd designs that they reached for when they needed absolute bulletproof reliability.

[J Tiers]

....
They do describe it for what it is, just read the data plate!

Well, "Synchronous/Stepping" is what it says on the data plate. But evidently it cannot function as a "stepping" motor, so why that is part of the description is puzzling. Apparently the "stepping" designation is just a confusing misnomer, perhaps included merely because it can be "locked" using DC. But it cannot be "stepped" by any means I can discover.

The only clue that is given is the lack of a "steps per rev" entry. I noted that and was suspicious of the data plate.

That publication I did not find on line with the searches I did. Searching under that name produces lists of engineers salaries, and other extraneous data. SE no longer is involved with such motors.

[MaxHeadRoom]

SE liquidated the Co back in 1980's due to lack of international sales etc.
The design books I have are from the 1970's.
They show a section through a motor, rotor & stator, and it is basically a stepper motor but designed to sync to the AC frequency
Showing they have rotor teeth at a pitch of 50 two more than in the stator. Although being an AC synchronous motor, they do actually 'step' in practice.

.

[J Tiers]

Too bad.... The "step" that it does show, has a good deal of "authority" behind it.

[nickel-city-fab]

JT -- did you search on the name "sel syn motor", it is quite similar if not identical. Maybe same thing under a different name? I recall seeing one of these things in one of my electronics textbooks, but darned if I can find the book!!

Here's a good explainer, IMHO from a Navy guy: https://eugeneleeslover.com/AMMUNITION/SYNCHROS.html

[nickel-city-fab]

... and here is an even better documentation from GE:http://1stopmotorhouse.com/GE_Produc...ns_3S9890.html

I may be totally wrong here, but it almost looks like you could call these "analog steppers"

[MaxHeadRoom]

JT -- did you search on the name "sel syn motor", it is quite similar if not identical. Maybe same thing under a different name? I recall seeing one of these things in one of my electronics textbooks, but darned if I can find the book!!

Selsyn (Synchro) motors are a different animal.

https://www.allaboutcircuits.com/textbook/alternating-current/chpt-13/selsyn-synchro-motors/

Max

[The Artful Bodger]

I think this page describes the animal....http://www.industrial-electronics.com/emct_2e_5i.html

I have seen aircraft instruments which appear to work on this principle (B, below).

[J Tiers]

So it would seem. It is actually a "PSC" motor, and nothing to do with a stepper despite what it says at the top of the label.

What it looked like originally was a stepper that maybe had such a high inductance that it would not work well at fast pulse rates, accounting for what appeared to be a 60 Hz "pulse rate", but what turns out to be a plain old PSC motor with sine wave input and a run capacitor.

Booooorrrrrrring....... I got lots of little PSC motors. I admit I have got nothing that is 200 rpm, so maybe it will find a purpose.

[The Artful Bodger]

You really should read and understand the page I posted.

An insight into operation from both pulsed and sinusoidal power is provided by the arrangement shown in FIG. 17. In essence, the potentiometer constitutes a two-phase generator. One complete revolution of this potentiometer advances the angular position of the rotor by one tooth, in the same way that one cycle from a conventional ac supply would. With a rotor having 100 teeth (two 50-tooth sections), 100 revolutions of the potentiometer would be required for one complete revolution of the motor shaft. The positions of the potentiometer and motor always remain synchronously related—a given angular position of the motor can always be “recaptured” by turning the potentiometer back to its total angular displacement from “start” that previously corresponded to that motor position.

[J Tiers]

You really should read and understand the page I posted.

the potentiometer plan is really a two phase illustration.

The writeup is fine, as far as it goes, but it is incomplete. It omits mention of the logic needed for the 3 wire version. I tried a lot of different logical inputs, and none would produce the effect of a stepping motor..

My conclusion was that I need a bipolar supply, but that is a big nuisance, requiring twice the parts and I have no money in this motor, so no need to "salvage an investment".

The logic for a type of motor I do not have (the 5 wire motor) is shown. My assumption is that the a' and b' notations for that are achievable in a 3 wire by reversing polarity, which requires 2 supplies, and double the usual number of switching devices, logic outputs, high voltage level shifters, etc. It is not clear that a suitable result cannot be had with a normal 48V supply and a normal large stepper at a lower overall cost than the 240V supply that appears to be needed to get this motor operating in a form of step mode....