I bought and installed a new 1.5kw water-cooled spindle with an inverter to run it. Now whenever I switch the spindle on it triggers my limit switches (in Mach 3) and I can only reset it when the spindle is not running.

I'm virtually at a standstill. Any help?

 

Things to try:

Add debounce to limit switches.

Add a line reactor like TCI's KDR series to VFD.

http://www.clrwtr.com/PDF/TCI-TRANS-COIL/TCI-KDR-Optimized-Drive-Reactors.pdf

Make sure your Spindle and limit switch wiring is all shielded and properly grounded.

 

Sounds like the noise or RF from the spindle power wiring is inducing noise and a false limit switch signal into that wiring.

You will need to separate those different wiring runs or cables at a minimum.

You may also have to shield the limit switch wiring by using shielded cable that has a shield you can ground, from just 1 end.
A conductive braid that you can wrap your wiring with and then ground that braid at 1 end only might also work.