[luca27973]

We have a mid-80s OKUMA LC-40 machine with SDU-600-W spindle drive unit. After we give spindle rotation command PH led will become red on the spindle drive unit SDU-600-W.
We checked fuse and they are OK, we checked phases on the line and theyare Ok. We replaced inductance and nothing change, we replace SDU and nothing change.We replace spindle motor and nothing change.
please note that SDU give us allarm only after spindle rotation command. At the insertion of the power SDU is fine with green leds ON.
Any idea????

Thanks
Luca

[OkumaWiz]

I'd check cables for a short. That vintage of machine has lots of miles on the cable movements and it could be that you've finally worn through the insulation and are shorting when the motor receives current with the M3 command.

Best regards,

BTW, you should have a drives manual for the machine that explains in more detail the PH led and troubleshooting techniques. Do you have the manual? More details on the alarm would be helpful.

[luca27973]

Hi,

we have the manual and PH failure is "missing Phase", "check for blown fuse".
We did it and fuse are not blown.
BTW we checked cable insulation with megger at 1000V and they are fine, more than 2GOhm.

At the moment we are stopped because after several test spindle drive blown.
Now we are repairing it to start again additional test but really we don't know what we have to check again.

Regards

[OkumaWiz]

Are you checking cable inside the motor or are you checking cable between the motor and the drive? I think you need to check from cable to ground with motor and drive unit disconnected and from cable to cable to make sure each phase is not shorted to other phase.

Best regards,

[luca27973]

we check cables form drive to motor and changed the motor, just in case....