3 phase motors, missing phase

[Tony S]

A centrifugalpump will spin the locknut and impeller right off and into the housing, quick as "snap there go the fins". Saw it done more than once and bought a rotation meter just for them.

Did you just happen to know two old guys “Albert and Dougie”? I’ll say I was happy when they both retired.

“The new pump and motor are on it just needs the power restoring”.
They hadn’t done rotation checks before the belts or coupling and guards were fitted. They always conveniently left it to the next shift to test run.

I fell for once, motor wrong direction and the impellor unscrewed itself. I never trusted them after that. I can think of better things to do at 01:00 than trying to get a 24” impellor screwed back on the chewed up shaft threads.
To refurbish an effluent pump would cost about £10,000 or $15,000 totally ruined for the sake of a rotation check.