Re: [CAD_CAM_EDM_DRO] Re: Hi frequency inverters and spindles

ddgman2001 wrote:

>I picked up the 7.5 HP Colombo spindle, now I'm on the hunt for an
>inverter. There aren't many 7.5 HP ones available, would there be
>any problem with using an inverter rated for 10 HP instead? Assuming
>the phase, Volts and freq. are all correct.
>
>
>

You can't assume! You need to find out what winding scheme is used
in that motor, anf go from there.

What RPM is it designed for?

Very few VFDs go higher than 400 Hz, and those that do are usually special
models, ie. not likely to find on the surplus market. AC Tech has a
model that
goes to 1000 Hz, and a few other makes do, too.

But, if the motor is not 3-phase, it gets a lot more complicated.

You can't pick VFDs by HP, you have to pick them by volts and amps that
the motor draws. For instance, my Westwind spindle runs on roughly 80 V
at 400 Hz. (It would want 160 V at 800 Hz, or 200 V @1000 Hz).
And, it wants 4.5 A at 400 Hz just to idle, although it probably is
generating
less than 1/4 Hp at that speed and freq. The rest is circulating
current because
of the low motor inductance. I also had to add series inductors between the
motor and VFD.

Jon