NICK D said:
Corner grounded delta is not allowed to have 3 fuses [240.22]. If you go with fuses, you have to put in a "slug" where the 3rd fuse would normally go. This slug can't be a piece of flattened conduit, it has to be a piece supplied from the manufacturer and listed for use as a fuse holder jumper/slug.
The conductor attached to the corner grounded termination of the delta is not only a phase conductor but also a grounded conductor. If you want to put a OCD on the corner grounded phase, you have to use a 3pole breaker that is "designed so that no pole can operate independently"
David