If you size the OCPD at 175, it will most likely trip on the inrush current. Assuming that there is secondary protection the primary OCPD can be 250% of the primary current. That would be 451 amps...you can't round up so you could use a 450 amp OCPD. If there is no secondary protection you can go up to 125% of the primary current and in this case you can round up to the next standard size, which would permit you to use a 250 amp OCPD. Note that the conductors between the primary OCPD and the transformer must have an ampacity equal to or greater than the rating of the primary OCPD.
