[dan_barber]

I've recently set up a new Lenze i550 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. The motor is a Leeson.

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 ?

[123CNC]

Are you running 3 phase power to the drive, or single phase?

Simple things first, double check the tightness of the input power terminals. If OK, trace back power lines from VFD all the way back to your building connection and main breaker panel.

See if you could rent a power analyzer rather than own such an expensive rarely used instrument. Your VFD is a much cheaper power analyzer, if you question the results of the one in service buy or borrow another to confirm if phase loss is valid. This should improve your odds of determining if the problem is in the power side or the VFD. Good luck.

[mactec54]

I've recently set up a new Lenze i550 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. The motor is a Leeson.

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 ?

I would say you have a noise problem, not a power problem, a photo of your wiring would tell me what you need to do to solve your problem, the lenze is a good VFD, if your power was a problem it would be affecting your other machinery, that is using your 3 Ph supply, the other thing, is your power supply 208v / 240v or something else

[RCaffin]

Check all connections!

Cheers
Roger