I work on very big VGT's

[Rawze]

(07-05-2021 )Wildcard Wrote:  ...
No tach feedback, it's just a WAG from programming motor parameters and motor speed at 60hz.
...

huge mistake with a system like that.. What cheap bas$tard would do such a thing is would I would be asking.

Open loop systems like that are always going to have issues... I would be looking into putting a tach on it and a better VSD instead of chasing surge, load balancing, and all sorts of other issues that can easily be avoided if it had been designed right to begin with.

I have worked with, and have designed from the ground up, drive and control systems far bigger than that in my day.