[Tinmuk]

I have some Superior Electric SS222E AC Synchronous motors. According to the SE brochure;

"The SLO-SYN motor is unique in that it has the capability of being operated as an AC synchronous, constant speed motor or as a phase switched DC stepper motor. In either case, it is classified as a permanent magnet inductor motor. Figure 1 shows the simplicity of the basic motor construction. Note that the motor has no brushes, commutators, belts or slip rings. Essentially, the motor consists of a rotor and a stator which make no physical contact at any time, due to a carefully maintained air gap. "

The motor has an 8 pin terminal block, of which only 7 pins are present. There are not further instructions in the brochure for wiring these. I have looked all over the internet and cannot find any info on driving these as steppers.

My question is: Can these be used as a standard 8 wire stepper? What is a phase switched DC stepper motor?

[ballendo]

That's an old brochure...

The word "unique" in the first sentence is simply no longer true (if it ever was)...

The staements made are true for ALL hybrid style steppers. (They ALL are synchronous motors which can be run at a constant speed or "as" a stepper.
Take most any synchronous multi phase motor and feed it square waves in the proper relationship and it will perform as a stepper. Feed it "stepped" sine waves and it will behave as a microstepping stepper. Feed it pure sine waves and it will rotate at its synchronous speed.

Basically a stepper is just a synchronous motor "fed" with various "simplified" sine waves. Think of it this way, a square wave is a sine wave of extremely LOW resolution. It's a digital "one bit" version of a sine wave. This gives us "full step" operation. Running a stepper half step just means giving it a little "bit"(pun intended<G>) better approximation of a sine wave. 1/4 stepping, 1/8 stepping and further microstepping resolutions just increase the "quality" of the digital sine waves you use to drive the motor.

Note that each motor is configured into --usually-- two coils and EACH coil is fed a "digital" sine wave of its own with one leading or lagging the other. This is almost always taken care of within the driver these days. So you feed the driver step and direction, and it feeds the coils...

The words "phase switched DC stepper motor" is simply a manufacturer's way of describing stepper operation to a--then--uninformed buyer base.

Fact is, you have some early steppers. (Or some early synchronous motors that "could" be used as steppers, but were sold and marked as synchronous. FWIW, LOTS of superior electric motors have been found on the surplus market over the years in both the "stepper" and "synchronous" labeling. And each can be used either way. Now the--potential--problem.

Eight wire motors ARE unique in that they CAN destroy the driver electronics if they are incorrectly wired. AND, there is no way to be CERTAIN of the wiring used short of Mfr's schematic OR disassembly. (Do NOT disassemble steppers! At BEST you will lose about 1/3 to 1/2 the available torque--and these older motors are ALREADY at a disadvantage in this respect-- while at WORST you will lose the operation of the motor entirely through the introduction of debris to the motor interior.)

So back to the motors...

With eight wires you have 4 coils, and since the motor is two phase, you will be using these 4 coils in parallel or series, to get effectively TWO coils. (with 4,5 or 6 wires going to the driver)

In simplistic terms the problem is that the coils have a "start" and "end". These need to be connected properly or the motor coil(s) behave(s) as if the coil is a dead short, destroying most drivers instantly.

Search/Read about "buck" and "Boost" in transformers to understand this a bit more...

Okay, so what to do?

You "should" be ble to find someone on the various groups with old Superior stepper motor info. I have some but your model number is not "familiar" to me
What are the wire colors?

You can safely connect two of the four coils at a time to a driver, at roughly half the torque. (note that some combinations will not work; but none should be devastating to a driver)

Hope this helps,

Ballendo

I have some Superior Electric SS222E AC Synchronous motors. According to the SE brochure;

"The SLO-SYN motor is unique in that it has the capability of being operated as an AC synchronous, constant speed motor or as a phase switched DC stepper motor. In either case, it is classified as a permanent magnet inductor motor. Figure 1 shows the simplicity of the basic motor construction. Note that the motor has no brushes, commutators, belts or slip rings. Essentially, the motor consists of a rotor and a stator which make no physical contact at any time, due to a carefully maintained air gap. "

The motor has an 8 pin terminal block, of which only 7 pins are present. There are not further instructions in the brochure for wiring these. I have looked all over the internet and cannot find any info on driving these as steppers.

My question is: Can these be used as a standard 8 wire stepper? What is a phase switched DC stepper motor?

[Tinmuk]

Ballendo,

Thanks for the informative reply. There are no wires, just an 8-pin terminal block. I can check them with an ohmeter to see where the coils are. Can I assume that energizing each coil one at a time with 24vdc would allow me to see if the motors even work? I could also determine the coil sequence from that, right?

If I put together a basic driver circut with a 5804 driver chip would that work for testing?

I have heard that a three wire SLo-syn can be modified internally to become a stepper, but since this one is an 8pin I am hoping it will work.

Thanks again for your help.