Assuming that we're talking about a motor/generator (MG) 10EE, 15A fuses will not work. During startup the MG draws about 100A for the first second or so. That's enough to pop a 15 or 20A, time delay fuse. As long as the internal wiring of the machine, from the disconnect to the MG, is still at the original 10 gauge wire size, 30A fuses are fine.
+1 The input has to drive the starting load of the 3-Phase AC Motor of the 'Motor-Generator'. That has slightly higher starting load/inrush than comparably-sized 3-P motors. The 'extra' comes from the 'primary' DC generator - same shaft - that drives the armature. That may have near-zero DC load at startup, but does add mechanical inertia & drag.
Same again with the 'exciter' DC Generator for field and control power. Straight belted, no clutch, that also adds some mechanical drag and inertia even if no DC load is yet being drawn.
Result is an at least 'slightly' harder start for the rating of the MG's 3-P motor section compared to a totally unloaded 3-P motor, same size.
The 'hollow state' electronics of the WiaD and Modular differ. Less greedy at initiation than a motor, but do have large transformers to serve and heater filaments to warm-up.
"Monarch Sidney" and any other solid-state DC Drive are gentler yet. Basically all those do is power-up their transistor / IC control electronics section, AND NOT their Thyristor pass-elements, may or may not provide field power right away, but even so, it is but 2 A or less.
Even when solid-state DC Drives are later asked to provide power, and with a fairly aggressive ramp-up, there still IS a ramp-up, or form of 'soft start', so there is no inrush to speak of.
VFD have a capacitor bank to charge, so should see a modestly heavier inrush at initiation than a DC Drive, but far less than an MG.
Bottom line is that fuse sizing goes by Monarch's 'book' for any of MG,. WiaD, Modular, powered systems. Then goes by the DC Drive or VFD maker's 'book' for either of those.
That's roughly five different 'drive' scenarios = 5 different fusing schemes.
Only one will matter for any given single 10EE but it involves activation "speed" of the fuse as well as Amperage rating.
Just be sure to select the 'right' one for your drive, remember to review that choice if/as/when making a major change, and adjust to the new situation.
