What drive for this DC motor?

[snaggletto]

Hello,
I'm interested in pricing a drive for a variable speed DC motor. The nameplate information is here;

http://members.cox.net/snaggletto/EMC Plate Right.jpg

I can't make much sense of it in terms of max RPM, armaure voltage, field voltage etc... The motor used a 1.25:1 gear reduction (belt driven) to the spindle. The manual that the machine came with claimed a max programmable speed of 4000RPM. So, 4000 X 1.25 = 5000RPM at the motor as top speed.

What voltage specs should I be looking for to match a drive up to this motor? Thanks.

 

[Skogsgurra]

Hello snagletto,

This motor can be fed from a thyristor drive with a 400 V DC output for the armature and a controlled field supply that automatically reduces the field current when speed goes above 1700 RPM.

The maximum speed for this motor is 6000 RPM (at 400 V/6.5 A armature and 37 V/0.11 A field) so it should cover your speed range.

If money permits, I would chose Siemen's type 6RA70 digital DC drive with automatic field weakening. I would also use speed feed-back since the speed will be quite load/temperature/mains voltage dependent when running with low field current.

Please note that the field winding needs a 20 mH DC inductor between supply and winding (Lv 20 mH 380 V 50 Hz). This is to prevent too much induced voltage from field to armature winding, which would lead to brush fire if no inductor fitted.

The motor also needs external cooling, so you will need either a separate fan or cooling air via a duct from a central supply.

 

[snaggletto]

Wow!
I'm impressed with knowledge at this site, and the speed of which I get responces.

I know very little about DC drives. The bit of looking I've done seems to turn up regenerative and non-regenerative types of drives. Also, there are drives that use SCR's and those that use PWM to control the motor.

I'm definitely on a budget and I originally intended to replace the motor with an AC drive (which I already have) and an inverter duty motor (see 60Hz motor at 120Hz thread). If I could find a nice, but affordable drive for this DC motor it would be another option for me. If the drives are going to be more than $400, then I would be better served with the AC drive and motor route.

I'll do some looking at the type of drive you recommended. Any other recommendations on drives for the DC motor in question would be appreciated. Thanks.