[GearHeadMech]

Hi there,

I have a new 5 axis CNC mill build that uses 2x DYN4 servo drives and 3x DYN2 servo drives.

I am having an issue with the performance of the DYN4 drives. Using the DMMDRV program for parameter tuning, motion and scope monitoring I am consistently getting overcurrent faults, as well as occasional Lost Phase faults. These faults occur with the motor connected to the load, and with the motor on its own. Small motor shaft disturbances cause the drive to fault, with various Main, Speed and Integration Gain values.

The DYN4 drives are DYN4-H01A2-00, both are wired identically. They are wired for 240V single phase, hot leads (L1 and L2) connected to R and S, with the same source powering the logic L1 and L2 with a 1A fuse on each line. All of the incoming power is filtered through EMI filters, 16A filters for the main power leads, 1A filters for the logic power leads. They each have a resistor connected to R1 and R2, as per the manual. I do not have a line reactor installed (LR1), the incoming power voltage is fairly consistent and stable. I've tried tuning the drive manually and with the Auto-Tuning feature without success. The Auto-Tuning faults at the high frequency sweep/test everytime (regardless of the test parameters inertia load matching, torque filter, position servo, belt or rigid connection). I tested the drive with 5 main gain, 5 speed gain, and 1 integration gain without success (127 Torque filter constant). The motor shaft can be manually rotated with little effort and then fault occurs, cutting power to the motor. A loud clunk/ stalling noise is heard. Sometimes I am able to run the sinusiodal test motion with a small position displacement and at frequencies below 4 Hz, past that it faults.

The 750 W motor has a brake (880-DST-A6_ _1), is connected to my Z-Axis. The Z-axis is driven by a 25 mm dia. ball screw with 5 mm pitch, directly coupled 1:1 with the servo motor. The Z-axis has a tunable pneumatic counterbalance offsetting the force due to gravity. The calculated load inertia is within the limits for the 750W servo and it should preform quite well. There is an audible humming coming from the motor when connected to either servo drive. I have 2 sets of motor and encoder cables and both sets of cables act the same, as do both drives. The humming does not change much with changes to any of the gain settings.

I scoped the encoder position in DMM DRV, and the encoder counts at steady state, with no motor shaft rotation only fluctuate +/- 2 counts, which suggests to me that the encoder, encoder cable, encoder connector connection to the drive is OK.

I am a bit stumped as to what to change next, or adjust. I've been in contact with DMM this week, awaiting some more answers from them.

[Jmhx2]

This is a very thorough description of the system and problem. I have been thinking about putting together a similar email to DMM, because I have been dealing with this problem for a few years. I installed three Dyn4 drives in a mill per the manual. After a couple of years I started experiencing over-temp, over current errors, along with the dreaded clunk sound when the drive shuts down. I have replaced two drives and after receiving lost-phase on my same Z motor w/brake, I replaced the motor. I am currently experiencing over-temp error on my X-axis. The weird thing about my scenario, I usually receive the error after I have run a job and the machine is a rest for a varied amount of time. However, I have had it error out while in the middle of a job, wasting material or breaking an end mill.
I had an axis that would fail autotune with resonance. I adjusted the gibs (tightening the axis) and was able to get through the sequence.
Prior to this mill, I installed 4 Dyn2 drives in my router. I have never had an issue with this setup.
I really like DMM products but with the dependability issues with the Dyn4 I am looking for other solutions.
Please update with what you or DMM find.

[GearHeadMech]

After more troubleshooting and with assistance from DMM, we found that there was an incorrect firmware setting on my DYN4 drive. The setting instructs the drive how many "motor pole pairs" the servo motor has. In this case the 880-DST motor has 5 motor pole pairs, and the drive setting was set to 4 which is more common for their other motors. In your case Jmhx2, it sounds like your drives and motors are working as expected, but wearing out? I would not have been even able to use my motor and drive combination in any machine given how it was performing before the firmware setting change.