Re: [CAD_CAM_EDM_DRO] Testing a 10HP Spindle with a 2HP VFD...Hmmm

Peter Renolds wrote:

>Hi VFD gurus,
>
>What have I done! I've just won eBay item #3836015794 which I intend
>to use to replace my entire BP clone's varispeed spindle/motor etc...
>Probably not going to run it much above 12,000 RPM without balanced
>tooling but that's going to be way better than the 4500 RPM I get now
>for faster feed rates, particularly with small diameter tools!
>
>Eventually I will get a suitable 10HP vector drive VFD but as I have a
>spare 2HP VFD, I was wondering if I could at least power up the unit
>without any load just to see/hear it run? Or am I likely to break the
>VFD? Yes, I have 3 phase power at my shop.
>
>

No, you may have problems with it. Most likely it won't destroy a good VFD,
but the 10 Hp motor has much lower inductance than the 2 HP drive is
expecting,
and the PWM mechanism may not be able to handle it.

Oh, even worse, it is a 400 Hz motor! No, you can't run this with a
standard
VFD at all! You will almost certainly need series inductors to bring
the inductance
up into the range the VFD requires. I have run a 1 Hp air bearing
drilling spindle with
a standard VFD, and needed to put an inductor on each of the 3 wires to
the motor.

Jon