Problem- Overcurrent/Field loss on spindle deceleration Fanuc 5t Nakamura and phase converter

[rolandkra]

Hello again, I have a Nakamura lathe with 5T controller and, after moving to a property out of town, am running it via a (undersized) phase controller.

I have successfully switched it on and homed it for the first time after a year sitting in the new shed, ( WhooHoo!!!) but now have a problem. I started the spindle on low speed and let it run for a while then raised the rpms up and down, again slowly, before switching the motor off at half speed. Bang! Something popped and I had a <machine> alarm. I turned the main switch off and then on a few seconds later and went through the same routine with the same result. The motor was not humming as sweetly as I remember from a year ago and reminded me of when I was running on 2 phases but not quite as growly (my word there)

I shut off and started again then, thinking I had a phase missing, raised the revs up towards maximum and found that it went up to 2500 rpm instead of the 3000 that it used to reach, but better than the 800 rpm when the fuse was blown. I switched the motor off which then triggered the alarm again and I shut down and restarted again right away without problems. I then brought the motor up to high speed, lowered the speed to minimum before turning the motor off and SUCCESS, nothing blew. I repeated this a few times with the same result so then I turned the motor off at high speed when the original problem returned.
The motor really shuts down quickly from high speed and this triggers the <Over Current/Field loss > alarm. Manually reducing the speed to minimum before turning the motor off avoids this problem.

I think that if I could extend the deceleration time, I could work with the machine.

I am running this via a 12 kW phase converter and wouldn't mind the limit of 2500rpm as I never seem to work above that. I wonder if the converter is contributing to or causing the problem.


Can anyone advise me on this?
regards, Roland

[rolandkra]

Here is a (hopefully) clearer description of the problem.

I've moved my Nakamura lathe with Fanuc 5T controller to another property and let it sit for a year.

It boots up properly but the spindle drive behaves badly

Following are the symptoms;

When I use the control panel to start the spindle, and the speed knob is in the lowest position, the motor turns on and makes a mild growling sound.

If I then turn the spindle speed knob quickly, the circuit trips and I get an alarm on the spindle drive board "over current/ field loss" after which I turn the power supply off then on again and re-boot the machine.

After starting the spindle again, when I turn the knob slowly to increase the speed, the motor follows but is a little rough sounding and it doesn't reach as high a speed as it used to nor accelerates as fast as it used to, ie: the motor doesn't keep up with the knob position. If the spindle is at 2000 RPM and I turn the knob to <full> (3000RPM) the spindle speed will increase over 20 seconds to only 2500 RPM . It sounds OK at that point.

If I press the spindle stop button at that point, or at any time when the spindle speed is above ~300 RPM, the circuit shuts down and I get the same alarm.

If the spindle is at any higher speed and I turn the knob quickly to reduce the speed, the circuit shuts down and I get the same alarm

If the spindle is running at high speed and I SLOWLY turn the knob to reduce the speed to around 300 RPM and then press the spindle stop button, the spindle stops as it should.

Would anyone be able to guide me on this problem?
regards, Roland

[gamalgold]

[good day
i have aproplem in fanuc oitd in the servo
alarm SVO 367
iwant help

[injunear]

What type of phase converter are you using?