Acorn 12 Spindle Speed Problem
Posted: Thu Apr 01, 2021 2:05 am
Hi Folks,
Here is Hyundai/Mazak 8G gang tool lathe with Acorn 12, DMM Dyn4 1.0kW motors, Siemens 360V 15hp spindle motor, and DuraPulse GS4 20hp VFD. I did all wiring with star ground coming to the ground plate. At this point no spindle encoder connected, yet.
The problem is--the spindle speed deviates and also, whenever I put M00 with 0 speed the spindle actually runs at some 95--100rpm with the 0-10v line shield not grounded. Once I ground the shield the RPM jumps to 200--205. Before I was running all VFD controls with 0-10V line in one shielded multiwire cable. Now I tried running the 0-10V in a separate shielded 2 conductor cable--no change. I tried to separate the power, logic, and analog rails--no changes. The different points of grounding--no changes.
The machine has an enormous power transformer (in separate compartment) with 3phase 220V in, giving out 3phase 360V, 3phase 220V, and 110V. Originally, I was feeding the spindle VFD with 360V, DMM with 3phase 220V, and Acorn with 110V, coming from that transformer. Thinking of reducing crosstalk I rewired the DMM to one phase 110V feeding off the wall. The same with Acorn. No any changes. Other than that everything works as it should and machine runs parts beautifully.
Do I miss something? The problem in short--when I leave the 0-10V line shield ungrounded the M00 with 0 RPM runs at 95-100RPM with some deviation, when I ground the shield it runs at 200--205RPM.
Best, M
Here is Hyundai/Mazak 8G gang tool lathe with Acorn 12, DMM Dyn4 1.0kW motors, Siemens 360V 15hp spindle motor, and DuraPulse GS4 20hp VFD. I did all wiring with star ground coming to the ground plate. At this point no spindle encoder connected, yet.
The problem is--the spindle speed deviates and also, whenever I put M00 with 0 speed the spindle actually runs at some 95--100rpm with the 0-10v line shield not grounded. Once I ground the shield the RPM jumps to 200--205. Before I was running all VFD controls with 0-10V line in one shielded multiwire cable. Now I tried running the 0-10V in a separate shielded 2 conductor cable--no change. I tried to separate the power, logic, and analog rails--no changes. The different points of grounding--no changes.
The machine has an enormous power transformer (in separate compartment) with 3phase 220V in, giving out 3phase 360V, 3phase 220V, and 110V. Originally, I was feeding the spindle VFD with 360V, DMM with 3phase 220V, and Acorn with 110V, coming from that transformer. Thinking of reducing crosstalk I rewired the DMM to one phase 110V feeding off the wall. The same with Acorn. No any changes. Other than that everything works as it should and machine runs parts beautifully.
Do I miss something? The problem in short--when I leave the 0-10V line shield ungrounded the M00 with 0 RPM runs at 95-100RPM with some deviation, when I ground the shield it runs at 200--205RPM.
Best, M