It is not a NEMA configuration. It might be a configuration related to OTHER approved types. It does look like a plug you might see on something from Europe but there are also Calofornia configurations too. I'd guess it is about a 30 amp plug with a ground, neutral and 3 phase conductors. Not a normal shore power configuration for RV or Boats. I'd guess data processing gear. but definitely something that needs a neutral.
