Thread: Arboga EM825 motor rewind

Guys,

Thanks for your kind words following my post - apologies for the delayed reply.

Joe, the rewound motor runs well at both speeds (ie four pole mode and two pole mode), both on or off the VFD. Since the nameplate top spindle speed is 2900rpm I don't feel the need to run it faster, and this speed is comfortably achieved in 4 pole mode with the VFD set to deliver 100Hz, so there really is no need to operate the motor in two pole mode at all. If both motor speeds remain easily available with the existing switch, I know that sooner or later I will get involved with the job and without thinking will change motor speeds but forget to switch off the VFD first. Also, it turns out that switching off the VFD between speed changes is s-l-o-w because of the time taken for the VFD to shut down. I do not want the VFD for speeds greater than originally provided.

Stuart, re the method of setting the VFD base frequency to 29Hz for running a 415V motor on 240V, the effect is that the motor has full torque only up to 29Hz and above that torque is progressively reduced. I expect that in some cases 415V machinery runs just fine (in the home shed) on 240V, but I did not like this solution for the EM 825, and the rewind fixed it (satisfactory glove test).

BTW I have misgivings about disclosing the 'glove test' - be warned that it is potentially dangerous. If the rotating part catches a full wrap of the glove you will either stall the spindle or risk serious injury.

I'm now thinking about the fact that the table of the EM825 has no central T-slot so there is no easy way of securing the vice and rotary table. The plan here is to find some MS plate (possibly cast iron) and make a fixture plate to take these items. In the unlikely event of having a spare day, I will drill and tap a grid pattern of holes in the plate to save time with future setups.

Bill


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