A three-phase 15Hp 230/460Vac 1800RPM motor is standard in the 254T frame in a TEFC (Fan Cooled) or DP (Drip Proof) enclosure.
You list the RPM as 1700; what does the motor nameplate say? A Four-Pole motor is 1800RPM 'synchronous speed,' but the nameplate will always be LESS; 1775RPM, 1760RPM, etc.
If the RPM on your motor is much less than 1800, and closer to 1700 e.g. 1725, 1710, etc., then see if the nameplate also shows the NEMA design. The higher RPM is a #standard# NEMA 'B' or 'C' design. The lower RPM may be a NEMA design 'D'; which is called 'High Slip,' and produces much higher starting torque.
NEMA design 'D' motors are used on punch presses, forges, etc., where you have to start a heavy inertial load.