Hi all
Most have replaced the DC spindle with an AC + VFD drive. I decided to take the less travelled path and keep the original spindle.
Briefly this is how it is supposed to work:
0 RPM->1700 RPM: field voltage constant at 310VDC.
Varying armature voltage from 73VDC to 400VDC at constant current yields constant torque output, 50RPM to 1700RPM
1700->6000 RPM: armature voltage constant at 400VDC.
Reducing field voltage from 310VDC to 73VDC yields constant hp output, 1700RPM up to 6000RPM
The ABB DCS402.075 is the drive I am using. Full of features but commissioning is not for the light hearted (using rs232 and DWL software)
The EMCO transformer provides 333V 3 phases (coincidently the 120P can go up to 5000 rpm which is 333V DC via interpolation). The ABB DC drive calls for 380V 3phases.
I plan to use Mach3 + ESS + C32 (cnc4pc) for the retrofit. I did an emco Mill this summer and all worked out fine.
I will use the Analog ouput (10V) from C32 (port VFD) to control the spindle speed.
Got
The original Encoder has 4 wires: 0V, 5V, 360PPR and 1 PPR while the ABB DC drive calls for A+/- B+/- Z+/- 0/5V but accepts single ended encoders.
So 360ppr wire to A+ should suffice for speed control ? I was told to connect 1 PPR to B+ ... not sure about it.
ABB Drive details:
ABB DCS400
thanks for any pointer.