ECN Forum Forums General Topics of the Trade General Discussion Area Wye/delta fire pump motor question

poorboy,
Nema rates a 150 hp motor at 180 amperes at 480 3 phase. (180 amps x 1.75 = 315 amps). Use the FLA that is on your motor nameplate.
The fuses or breaker will be 300 amp. Now figure your wire size for this current. Not the nameplate FLA. Size your overload for the motor nameplate FLA.

The motor uses all six leads for wye and delta, with the wye having leads 4,5,and 6 tied together momentarily. Connect all three contactors as shown on your diagram. "trust me, you may not get it right the first time you try to run it"......lol

Since this is a fire pump it may not be considered continuous duty. That will change your values.