Servo motor applications for hobbyist ? / General Science and Electronics / Forums

Forums

4hv.org :: Forums :: General Science and Electronics

« Previous topic | Next topic »

Servo motor applications for hobbyist ?

Move Thread

LAN_403

RogerInOhio

Sun Jan 31 2010, 03:27PM

Registered Member #1034 Joined: Sat Sept 29 2007, 12:50PM
Location: Chillicothe, Ohio
Posts: 154

Dose anyone know if the boat anchor in the picture is useful for anything? I was thinking it might be useful ether as a synchronous motor for a rotary spark gap or as an alternator in a wind mill.

A servo motor like the one below is a lot like a four pole permanent magnet three phase synchronous motor but there are some strange differences that I don't understand. Like in the literature below, where are the south poles?

The reason I'm asking this is that the plant I work at is throwing away a bunch of these and I might be able to get my hands on some of them. Also there are some on eBay that have starting bids of around $4.00 plus shipping. If you buy one of these motors new from the manufacture it can cost thousands of dollars!

Mads Barnkob

Sun Jan 31 2010, 05:59PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

The problem would be the lacking power supplies, inverters, controllers and communication modules.. :(

radiotech

Sun Jan 31 2010, 06:00PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

It looks like a Selsyn.Or maybe a SloSyn. A selsyn needs an AC voltage, an 2 units, and acts like a positional rotation transmitter. A SloSyn is a low speed type of stepper that needs a capacitor and an AC voltage and acts like a slow high torques motor without need for a gearhead.

Why dont you power them up and find out what they can do?

RogerInOhio

Sat Feb 06 2010, 02:22PM

Registered Member #1034 Joined: Sat Sept 29 2007, 12:50PM
Location: Chillicothe, Ohio
Posts: 154

Thanks for the input. I did manage to get permission to take home four servo motors out of all the stuff my company sent to the scrap yard. They are similar to the one in the picture and where used to turn ball screws that move machine axises for CNC machining.

If I use one of them for anything it would probably be for a generator. All my Tesla coils are DC resonant charging so I don't have a need for a synchronous rotary spark gap.

Sulaiman

Sat Feb 06 2010, 04:38PM

Registered Member #162 Joined: Mon Feb 13 2006, 10:25AM
Location: United Kingdom
Posts: 3140

Where I work we repair these motors and their associated drives (Drive = inverter)

These are high-speed servo/spindle motors of several (forgot how many) kW rating.
The rating plate on the side is your guide.
They are used for milling, turning, motion etc.
They are excellent motors.

If you have 3-phase you can connect directly.
(Secure the motor well or it will scare the s**t out of you when it starts up.)
You can run it as a synchronous (RSG ?) motor by applying ac to two of the wires and a capacitor from either of those two to the third wire.
Which wire you use will determine the direction of rotation.
This is a 'kludge' .. it's MUCH better to buy a drive.
ANY 3-phase output drive of the correct rating will work, not necessarily a fanuc drive.

These motors can be sold off easily.

Steve Conner

Sat Feb 06 2010, 05:44PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

RogerInOhio wrote ...

A servo motor like the one below is a lot like a four pole permanent magnet three phase synchronous motor but there are some strange differences that I don't understand. Like in the literature below, where are the south poles?

I think these ARE 4-pole permanent magnet synchronous motors and the lack of south poles is a misprint. Either that or GE have a secret stash of magnetic monopoles.

They're certainly not Selsyns or Slosyns as was suggested.

RogerInOhio

Sat Feb 06 2010, 06:19PM

Registered Member #1034 Joined: Sat Sept 29 2007, 12:50PM
Location: Chillicothe, Ohio
Posts: 154

If you have 3-phase you can connect directly.
(Secure the motor well or it will scare the s**t out of you when it starts up.)
You can run it as a synchronous (RSG ?) motor by applying ac to two of the wires and a capacitor from either of those two to the third wire.
Which wire you use will determine the direction of rotation.

I kind of thought I could get one to run like that but I never tried it. I have seen many post on this form and other forms from people trying to build synchronous rotary spark gaps and they end up having to modify an induction motor to make it run in step with the line frequency. It seems to me that a servo motor of this type would be a better alternative.

These motors can be sold off easily.

My company just scraped out five CNC machines and all they saved from them was the electronics for spare parts. They didn't save any motors and all together there where about 30 servo motors and 8 spindle motors. I would have liked to gotten all of them but getting permission from the company to take stuff home is kind of tricky and I didn't want to push my luck. I might just go to the scrap yard and see how much they will sell them for.

Moderator(s): Chris Russell, Noelle, Alex, Tesladownunder, Dave Marshall, Dave Billington, Bjørn, Steve Conner, Wolfram, Kizmo, Mads Barnkob