Mitsubishi FR-SX-2-11K acceleration/deceleration rate

Hello all,

I am trying to adjust the acceleration/deceleration rate of a Mitsubishi FR-SX-2-11K with regenerative braking. The unit is fitted to a 1988 Mazak QuickTurn 10N lathe, T3 Mazatrol control.

There does not seem to be a parameter for setting the acceleration/deceleration in the CNC control (though there are parameters for practically everything else!) However in the FR-SX AC drive manual I did find a setting for changing the time constant for acceleration/deceleration. This is switch SW3- positions 3,4, and 5. Range is 0.3 seconds to 10 seconds in eight increments. Ah-ha, I thought, just what I need! But the settings seem to have no effect on the spindle acceleration. It was set for 0.3, the book say the factory setting is 1.5 seconds, and I tried up to 10 seconds. No difference; it tries to accelerate the spindle as quickly as it can. The book does say that when changing the DIP switches, that to be sure to operate the reset switch (ST1). I assume all this is to be done when the power is completely off; which is the safest assumption (from an electrocution standpoint!) But since there is no change, I am wondering if there needs to be power to the board for the reset to work? Before doing so, I thought I would ask. With the power off, I assume pushing the reset switch drains a capacitor or some such to cause the reset to work.

Or is this inverter acceleration/deceleration setting simply not going to have an effect on the spindle acceleration while the program is running anyway? I have also tested the acceleration/deceleration in MDI mode. That is set the spindle for 2k and press the spindle CW and spindle Stop key alternately. Again, changing the DIP switch settings does not seem to have an impact. I would expect to see a difference between the 0.3 second and the 10 second settings.

I am running it off a 20hp RPC, voltages balanced, phase direction positive (not that the inverter is supposed to care.) However during peak acceleration and deceleration I am getting voltage/current fluctuations, which every now and then cause the controller to throw an e-stop. I have done about all I can do in regards to upgrading the wiring to 75amps (the machine was fused for 100amps at the shop it came from). The machine is wired with #2 back to the RPC (when the electrician cut it loose in the other shop, I had them cut the drop cord at the 'other' end. No sense buying drop cord if you can get it with the machine!) Short of re-wiring my whole workshop (#6 going to the RPC), I am sort of stuck with this for now. Hence I thought I would try to tame the acceleration and so cut the peak loads, which is the only point where I seem to be having a problem. Under steady load with the spindle running at 2k, I am pulling about 30amp per phase, which is what I expected.

Thanks,
Doug