we need to get a battery charger for an electric transport vehicle working in the USA. We can't simply use another local charger because we have complex features and functions in the charger.
We have a power consumption of 3400 Watts. The chargers accept both 50 and 60 Hz. There is a 230V 14 Amp single phase version and a 400V 3-phase + N (5 amp per phase) version so we will need a transformer anyway.
Is there a common outlet (as far as I know, three-phase is not available everywhere) where we have the highest chance of availability at the customers site? Does it depend on the kind of industry? What about non-industrial buildings, which outlet is the next common behind nema 5-15?
Sounds like you'd be best off with 240 V 20 amp (in theory 15 amp would be enough but I think that'd be a violation of the rule that circuits shall only be loaded up to 80% under normal conditions). 30 amp 240 V is common for clothes dryers so if that's OK for short-circuit protection I think I'd go for that.
Complex features? Does that mean you need four wires (two hots, a neutral, and a ground?)
There are two answers- the 'legal' and the 'useful.'
First, the legal answer... Ordinarily, your charger would be submitted to someone like UL for evaluation and testing. As part of their examination, it would be decided exactly what plug and over-current protection your charger should have.
There's been a lot of work in this area recently, as truck stops are being required to install 'power stations' for each parked truck. Also, with more electric vehicles being proposed, this area has been quite active. Some plug patterns might be set aside or standardized for this use.
As for the "useful" answer, nearly every home has a 30-A/230V receptacle for the clothes dryer. Using such a circuit might even be legal, considering what overcurrent protection might be part of the charging station.
Air conditioning units typically have power somewhere around 25A/230V. Unfortunately, such units are also hard-wired to a disconnect. That disconnect might be a convenient place to add a receptacle, though.
We use the term "U/L" to designate a tested and listed product but there are other labs that are "Nationally Recognized". In Europe that might be TUL Germany.
One easy way to accommodate different line sets is to use the IEC320 inlet on the equipment end and then supply a listed line cord with the appropriate plug on the line side. (similar to the way PCs are powered)