Wye Delta starter breaker trip on Startup

[NNPackerfan]

I have a Wye-Delta starter (440VAC) with a 800hp motor and am having intermittent tripping during motor starting. Motor LRA test data (Delta-Run) is 5980 amps and motor manufacturer and various publications are estimating that starting current in Y should be approximately 1/3 of the delta value. The installed breaker has a 1000Y element installed and is tripping with instantaneous set at band 3 (4000 amps) and in some cases band 4 (5000 amps), the starter is closed transition.

Have measured starting current for this application and are getting spikes that are well in excess of what would be expected even taking into consideration motor magnetization. Any ideas what could cause high starting current in this sort of application?

 

[jbartos]

Suggestion: Digressions from original posts often happen if the author of the original post is less pro-active.

 

[GGOSS]

Oooops,

Correction to my post of July 29, 2003. Forth paragraph should read "do NOT experience the problems raised by others".

Regards,
Slightly embarassed GGOSS