Digital drive for old shunt wound motor


Thread Starter

Mark Cosin

I want to drive an old 1/2 HP, 230V armature, 200V field DC brush motor, previously driven by an amplidyne [we are talking about 1960 stuff]. I have found many SCR analog drives suited for 180V armature, 1/2 HP, many of them also supplying the field voltage.

I wish to close the position loop using an encoder, however I cannot find a digital drive with the same specifications. Therefore I have two questions:

1. Can I use a separate motion controller, feed the +-10V to the SCR analog drive, and get decent response after a bit of tuning?

2. Is there any digital drive for this kind of motor? If not, why [i.e.: is there a technical reason, or just there is no demand]?



The demand is low on digital DC drives for single phase. The only one in existance that I know of is the 590SP made by formerly Eurotherm Drives now known as Parker Hannifin/SSD Drives Division. (they were bought by Parker). In fact I don't see the 590SP on their website so I don't know if that demand is down and they still have them for new applications, I know they would supply them or parts for existing installations, they are very good about that.

Anyways, I have used hundreds of these and they work well. They have some configurability to them for applications i.e. winding/tension control. You don't mention your application, so I can't say that it is a good fit or not. Expect to pay quite a bit more than just a plain old analog drive. I believe these drives can take 110-400vac single phase depending on the model etc. This can handle an encoder for feedback, but as far as position control you would have to use an external controller.

However, This drive doesn't do position control. So with out application information, I am not sure that you really need position control on a old 1/2HP dc motor. If you truly need position control, and me assumuming your motor is a 56C frame Parker makes a 56C face servo motor (MPL or MPM series I believe) that could bolt up to where your existing motor is, then use one of their intelligent drives to do position control in one unit.

If you want more help post more details. And yes you can get decent response from an analog drive using an external controller. Though, you have to know what you want and what you are doing.

Just another FYI, I have used SSD Drives 590+ to run 7.5HP 230V Arm, 200V Field motors before, this is a three phase drive though, and they are still running great today 5+ years later.

Drive Guy
I forgot to mention, you can also get an AC vector motor with a 56C frame, many AC drives that are multi-purpose can do position control with many different types of feedback. You could easily retrofit to an AC Motor and use a drive such as the 890 from SSD or the Unidrive SP from Emerson/CT... just to name a few.
Thanks for all the information. The motor is used in an electromechanical universal testing machine. I could get by with a decently accurate velocity control, though position control would certainly be great.

Hi, Mark.

I also have a universal testing machine with amplidyne and would like to compare notes.