Parker CSM Motor/Amp successes & further road-blocks

[Stuff-Builder]

Hi All,

Several years ago I picked up a whole mess of CSM (Parker) servo motors and a few amps from my employer who was going out of business. They were all matched and so I figured I might be able to get them to work. Recently I've been getting to work on them.

I picked up the fancy MIL connector to go on the motor (see rule 1 - always grab the cables too) and got a motor/resolver cable soldered up. I plugged a motor in and powered up the drive (a brand new unwrapped model) and PRESTO! everything seemed fine. No errors on drive, and the motor shaft was locked up tight.

Plugged in the second drive - this one has seen some use somewhere - and also no errors but the same motor now spins continuously. I tried messing with the pots and making sure the settings were the same as the first drive, but no success making it hold still.

Plugged in the third drive - this one had a RED TAG from the auto plant where it was installed - POW! let the smoke out of it. Two for three ain't bad...

So I'm planning on using some Rutex R2040 drivers to give the amps their +/-10 vdc signal, so I got a couple of 9 volt batteries and rigged up the tester shown in the Rutex manual.

Ran the first drive, and everything worked perfectly! I was so happy I could have done a stir-dance.

Second drive, however, still had it's constant rotation (4000 rpm according to my touchless-tach), and would not respond to the analog input at all. Any ideas on what might be the issue? I'd like to salvage this drive and use it for my mill conversion. I can give links or forward all the factory info if needed.

Another question: the motors are all labelled 230 VAC, but the drives are labelled 80-260 VAC 1ph. I found out through my tests that they will run at 115 vac, but what's the effect? Slower speed? Less torque? Spontaneous explosion? Is it BAD to run a motor at a lower voltage like this? Ultimately I'll build up a 230 VAC panel for them, but for testing the 115 is much more convenient.

Also, does anyone know of a relatively inexpensive drive/amp for AC servos? The motors are all 230 VAC, mostly Trap, and have resolvers. Some have brakes. They're all around 1 hp. I've got a lot of motors...

Thanks for reading my saga, Scott

[Al_The_Man]

The good news is, these are AC sinusoidal motors and amps. The down side is there is no relatively inexpensive drives for these, you could try Granite devices, however.
On 120vac your PS DC is around 165vdc, on 240vac your DC will be up to 330vdc.
This is usually not a problem, as rpm is relative to voltage, and the drives or controller can restrict the max rpm to the motor rpm rating.
The second drive is looks like it is in a runaway condition, this may be an pot. adjustment or a parameter, depending on what intelligence the drive has, if any.
Al.

[Stuff-Builder]

Al, thanks for the info. If anyone hasn't told you lately, You're the man!

That makes sense that voltage matches RPM, because on the good drive I measured a max RPM in each direction of around 2500. The motor is labelled at 6000 RPM, so you figure half speed and my test max being 9 volts rather than 10 and everything looks good.

I'm hoping I can cure the runaway condition. There's not a lot of intelligence in the amp itself. I've checked all the dip switches and they look fine. I hunted around on the board and couldn't find all the jumpers. It's kind of strange - there's a bunch of jumper wires added to the board - some of it pretty hack work. Doesn't look like a factory job. Maybe I'll shoot a picture.

With regard to AC servos versus brushless DC , what does this really mean? What is the motor actually receiving? It does look like one of those Granite drives might do the job - runs AC, accept hall sensor feedback (resolver, right?), takes a step & direction from Mach. The price at roughly $250 is good too. May have to shoot them an e-mail.

Thanks, Scott

[Al_The_Man]

Resolver is not hall sensor, hall effect is commutation for BLDC, the switch is more coarse that sinusoidal which is true AC and represent synchronous motor control.
AC sinusoidal switch a 3 phase variable frequency and amplitude signal to the stator.
BLDC, although having the same winding representation, have only two windings fully energized at any given moment, Hence the DC in BLDC.
Al.

[Stuff-Builder]

Well, if it won't do resolvers then it won't work for these motors. They're all resolver feedback.

Looking at the nameplates, most of them are trapezoidal motors too.

I was looking at the Elmo servo amps and they seem to be able to handle everything I need. Definitely not "hobby stuff" but maybe that's not a bad thing.

[Al_The_Man]

An alternative is to try them as BLDC, use the Renco encoders being dumped on ebay and convert them. You need to find out the pole count, however.
Al.

[Stuff-Builder]

I played around with my problem amp a little more this morning. By changing the pots, I did get it to respond to the +/- 9V signal, but it's not as smooth as the other amp. It seems to still have some sort of bias in one direction. I have to mess around with the balance and see if I can get it to stabilize.

I saw more of these MPA-03 amps on ebay - a few for not much money - but I'm a little afraid of buying them. I don't want to shell out bucks and have them be dead amps.