why some motors star point earthed?

Don't know if this applies but I used to work with large chillers that had star\delta wired starters. Chiller would start in the star windings(lower V&I then after a few seconds would switch to delta ...more efficient.
 
M

Manmohan Sreedhar

could be as part of a protection scheme. with a ct on the star earthing cable neutral current which will be zero unless there is a phase imbalance can be detected.

i have seen large HT motors with a neutral junction box. this coms in handy for testing and also can be used to provide differential protection.
 
Responding to Mike's Thu, Feb 13, 9:48pm, comment:

Sorry, but I disagree! If the wye-point of wye-delta motor (used for starting) is intentionally grounded, then upon transfer to the delta
configuration a line-to-ground fault would ensue.

I believe that jatinder was referring to a normally configured wye-winding motor, not a wye-delta one.

Regards,
Phil Corso, PE
(Boca Raton, FL) [[email protected]] {[email protected]}
 
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