3 phase power analysis (Troubleshooting VFD issues)

[andrewwong2000]

I've recently set up a new Lenze SMV 4kw 3phase VFD to run a 3kW 3 phase motor, but have an intermittent "input phase loss" issue.
Really annoying if you want to run the motor for any length of time!

I'm stumped to figure out how to solve it, and am not sure if it's my VFD, the supply, between the vfd and the mains. My direct start
3 phase machinery works fine but the VFD is not totally reliable.

So the engineer in me says I need to really understand what's going on with the power and see if I am really losing a phase, or if it's the front end of the VFD.. or the mains supply.

As I'm planning to buy another VFD for a future CNC project, I'm thinking about buying a 3 phase analyzer to sort this out once (and for all). Do the cheaper $1500 EBay taiwan/chinese 3 phase analysers do a reasonable job of detecting dips/swells, phase, PF issues or should I be going to something more expensive ?