What is the purpose of this device? (Lamsa 15kVA)

I'm not an expert, but it looks like a transformer to me.

I believe this allows you to input 115 to 230v (50 or 60Hz) and puts out a clean 230v for you.

Yeah, probably some sort of isolation transformer.
Hard to tell without seeing how it's wired into the system

Special design only for use on the moon.

Off topic, but a few years ago ASEA was developing liquid cooled shore power converters to eliminate the high heat out put, and also allow the units to be installed in a high ambient area.
Another well known mega yacht builder I worked with had to install large A/C air handlers in their shore power converter install area, which lead to a significant increase in A/C chiller size.
Gotta dissipate all that heat somewhere.

Our ASEA units are cooled from our chiller loop.

Definitely not. ASEA is much more sophisticated than a simple isolation transformer.

2- 45kVA units. Yes, HVAC must be running when plugged into shore power.

That begs the question:
How do you cool the ASEA units when you are using the chiller loop to HEAT the boat in the winter?

Most air handlers require the loop to be above 105 degrees for the klixons to become active and normal loop temp is in the 110-115 range.
Or have they configured the heat output from the ASEA's into the heating loop cycle, and they will tolerate the 115 degree operating temp??

I ask because I recently did 3 winters docked in northern Italy and heating was extremely important. And yes, I did have conventionally cooled ASEA units in the engine room and kept temps mostly acceptable with all fire dampers closed limiting the ingress of cold air. We also had a large 3 phase immersion heater in the loop for general boat heating. I was also able to isolate sections of the boat not being used, like the entire guest area and forward lounge etc.

We haven't had to consider it, as all our air handlers have heat strips. We've spent the last two September/October (early) in Maine, and needed heat then. But otherwise, we're always looking for cooling.