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star/delta o/load

star/delta o/load

star/delta o/load

(OP)
i have a 3 phase motor  pump rated at 17.9A full load do i fit an o/load in the main contactor line and set it at 11A this being 17.9/sqrt3

RE: star/delta o/load

Yes, if this is a standard Y/D starter with O/L relay on the load side (in series with motor windings), of the main contactor.  In other words if the O/L relay is seeing the phase currents of the delta conection then your statement is true.

RE: star/delta o/load

Regularly on wye-delta starters the full load current of the motor is shared between two contactors ( 1M and 2M), then the thermal units must be sized for 58% of the full load ampere rating of the motor .

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