There is no way to convert the 400cyc alternator on there to 60 cyc output. The -frequency- is determined by the number of physical poles/slots in the stator, times the RPM. Obviously, you cannot change the way the laminations in the stator were machined/made.....i.e., stamped.
A 400cyc alternator designed for 1800rpm would put out 60cyc as-is IF you could run the engine around 250 rpm..
(but even then, it wouldn't work worth a damn. It'd overheat even at moderate load, because the amount of iron required for 400hz magnetic fields is far less than for 60hz fields....which is why 400hz power is used on aircraft (gens and motors and xformers are lots lighter).
A "phase converter" isn't relevant to this situation. A phase converter is a device for creating 3-phase output from a single-phase input.....using either large oil-filled capacitors or a 3-phase motor plus a capacitor.
Phase-converters do NOT change the FREQUENCY.
There are two post-genset methods of "changing" the frequency. I put "changing" in quotes because in both methods, what's actually happening is that the power is being 'created' over again from scratch.
The first method is a simple motor-generator rig....which someone mentioned already. But you'd need a 25hp 400-cyc AC motor to begin with....not easy to find.....and that would drive a 10kw 60cyc alternator (i.e. generator or gen-head). Those are easy to find, but costly. Then fab a frame, drive-coupling, etc. etc..
But if one were going to buy a 10kw gen-head, one might as well just bolt it to the diesel in place of the current 400cps gen-head...
Also, motor-gens are typically only 60-70% efficient...quite a large loss.
The second "frequency converter" method is "electronic"; in that it first rectifies the 400cps to HVDC, which powers a very large power-amplifier, which amplifies a 60-cycle signal from an oscillator.
These are the big, heavy, rack-mount boxes you see for several grand.
Best method to get 60hz from that rig is to buy a 15kw gasser genset with a blown engine, take off its gen-head, and bolt it onto your diesel. Should be doable for 500 bucks total cost.....or less if you get lucky finding a gen-head.
Note; if you're close to a port at all, check for a company who services the work-boat gen-sets. They almost always have a pile of old gen-heads in the weeds out back.....from gen-sets which blew the engine, and the owner decided to replace, rather than repair. I've gotten 10-20kw heads for $100-300 more than once. Basically for the scrap copper value.
hope this helps...
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