[Arjuna]

Hello everyone,
i have a S01 SERVO ALARM:PR 0071 with MITSUBISHI MDS-B-SP-185 (spindle) and MDS-A-V1-45 and MDS-A-V2-3535 for axes.
It just appears after some time working (sometimes over an hour or more of work) and machine stops because of that.
I can't figure out pattern that triggers that alarm...Alarm manual says that 0071 alarm means INSTANTANEOUS POWER INTERRUPTION.
Machine monitor also displays STAR-DELTA SWITCHING PROBLEM under S01 ALARM but i don't think that's a problem because spindle rotates at 6000 RPM (program set) all the way, so STAR-DELTA switching occurs only at power up and power down.
Pieces which are manufactured are aluminum cubes with gentle cycles so any harsh movement and overloading of driver isn't the case.
Also i'm not sure for what that alarm stands for...i found it under axes alarm, so that would indicate axes servo driving error but machine monitor also displays SPINDLE AMPLIFIER ALARM (i guess because of STAR-DELTA).
Just to mention, DC link is about 280V at 6000RPM without load so that's OK i guess, but i didn't measure PSU DC with load, that's my next step.
Here it is, if anyone can comment a bit this issue it will be greatly appreciated, thanks guys!

[Night Shift Wiz]

Just had an instance where the X-Z servo drive module went dead. Pulled it out and found the cooling fan was so gummed up with coolant overspray that it locked the fan up. The fan is 24VDC and runs off the internal power supply inside the drive, which shuts itself down when it senses an overload. Disconnected the fan and it came back to life.

It could be something similar. Your cooling fan could be getting gummed up and momentarily overloading the internal power supply.

The spindle module and the inverter module both had 440VAC fans. They would probably blow a fuse or burn open the windings if they gummed up. So I would check the servo drive first.

[Arjuna]

Thanks for reply!
Could be fan no doubt regarding there's no pattern at all for that alarm. Some time ago we changed Z axis lathe as suspicion was on that coordinate. Machine instantly refused it and reported same alarm again, so we replaced old lathe and it "worked" as before. Currently im preparing scope measurments for Z lathe signals to see what's going on there. And yes, there's sine to TTL signal converter between lathe and drive so im going to check signals before and after that converter. But again, I could save some time if i check fan first

[Rokkin]

Alarm 71 on the spindle is actually a CV unit alarm. it only appears on the spindle because it is linked to the power supply via CN4 cable. You'll notice that the CV unit will display an alarm also. You need to check the RST input going to the power supply. If there is a contactor feeding it, it could be a contactor problem or even the circuit that controls the contactor coil.

[Arjuna]

Yes, that's solution...I found 2 contactors with burnt contacts which apparently caused power failure. I just cleaned them and put them back in driver. I hope that anyone with the same problem will come to this thread!
Thanks guys!







Alarm 71 on the spindle is actually a CV unit alarm. it only appears on the spindle because it is linked to the power supply via CN4 cable. You'll notice that the CV unit will display an alarm also. You need to check the RST input going to the power supply. If there is a contactor feeding it, it could be a contactor problem or even the circuit that controls the contactor coil.