Hi all!
I have a Bridgeport Series II Interact 2 milling machine that I wish to retrofit to a new servo control but still using the old dc motors.
But I need a dc psu for the motors, and was thinking to maybe use the transformer in the control cabinet to do this.
Will be using the DG4S-16035 servo drive which has a max operating voltage of 160v.
The motors are t SEM MT30R4-58.
Attachment 262984
Volts 145
Cont. Stall Torque 3.2Nm
Max RPM 2500
Power output motor: 3.2Nm*2500rpm/10 =800W / 145V = 5,5A.
The Bridgeport has a big 3KVA transformer that was used to power the servomotor drives with 180v.
Attachment 262990
Seeing the electrical schematics in the manual it looks like it is an autotransformer?
Attachment 262994
For information I live in Norway and we have IT net which is 3x230v power here. I also have 400v from a transformer in my shop.
Now, what my idea is.. The transformer can be hooked up to various voltages to give out 180v as seen in schematic. They probably made one model to make it work for all markets..
380v to 180v is a reduction of (380/180) = 2,11 times
So if I were to connect 230v to the 380v (230/2,11) I would get about 109V, and when this is rectified (109v*1,4) would give me about 153V.
Quoting Al_the_man here
So the 153VDC rectified is perfect for motors and within spec for drives.For servo Power supply design the DC voltage should be at least 10% over the motor plate voltage, you can also go higher than this if needed.
Is it possible to simply do it like this? Obviously also have to put some decent caps and bleed resistor and maybe inrush limiter depending on size of caps..
I have looked at the wiring going to the terminals of 3KVA transformer and they appear to all be of the same gauge.
Still having read similar threads, I know there may be an issue with the efficiency, and derating of transformer when used like this..?
If the 800w per motor is true, then 2400w for all three motors is below transformer VA rating. I think I read an 80% requirement of total power req so about 2kw should be sufficient.