Phil: Obviously the unit must comply with safety regulations. Therefore the voltage MUST be less than 50V for safety, and probably (hopefully) a lot less... in fact I HOPE they have used the dcc standard since it already exists, and has 25% of the US market, and people likely to buy the loco to USE rather than leave in a box (why don't they just buy a photo or empty box 8-) ), are likely to also use or consider dcc track control.
Therefore consider 16V ac with control data as the switching frequency (dcc). Maximum current capability 5A (again toy train regulations) P=IV = 16 x 5 = 80Watts absolute maximum, and nothing else running. It will be less than this:
Note that it says it takes time to heat, and then runs for 25-30 minutes. (What volume of water can you get in the tender?? possibly 10cm3?
Now calculate 25min x60 seconds = 1500seconds and the latent heat of steam for the energy required to convert water at (100C) to steam, and ignore the preheating time to get the water to 100C in the first place (for this rough example)
(brain stress - is is 540Joules per gram???? itsa been a long time)
1500 seconds to consume 540J x 10cm3 (10g) 5400 1500 ....5400 15 ......54 Joules 5........18 Joules 1 second .... 3.5Joules which implies a lot less than 80Wobvously the actual figures work or the product wouldn't have been launched!
E+OE !
I look forward to reading more about it, and joining the queue to get a West Country!
Phil