You are still stuck with OPCD on the Secondary under 450.3(B)...
Primary only protection is disallowed by 240(F) which means that you must use line 2 from the table: PRIMARY & SECONDARY PROTECTION.
I have in my day installed a ton of dry-type delta-wye transformers. Without exception the AHJ looked for the secondary OCPD --- RIGHT OFF THE BAT EVERY TIME.
It remained on their hot list of common electrician errors.
I can't speak for your AHJ, but out here they are on this like white on rice. You'll get red-tagged every time.
Wrong, it is not about 3-phase transformers, it is about transformers with multiple output voltages.
Yes, 240.4(F) says the secondary conductors need protection except for single voltage secondaries.
But it is 240.21(C)that says where the conductor over current protection must be located on the secondary of a transformer and what size that protection can be.
450.3(B) only says the transformer primary must be protected at not more than 125%
except when a properly sized secondary protection is provided.
