I'm not an electrician either, but I think you want a tranfer switch between the utility power and any backup power source.
If not set up and isolated properly you can backfeed the grid through the transformer, stepping up the power, making it dangerouse to utility workers. Lineman really frown on that. Also if not done correctly and utility power is restored all your equipment may be fried as well as risk to your home circuits, fire, and electrocution. I have heard tales of linemen and power companies having uncooperative cutomers running a generator during a power outage. At least one of them insisted on not turning off and disconnecting his generator. The homeowner insisted it was installed correctly. The homeowner found out very dramatically it wasn't installed right when the utility restored power.
As an electrician, you need to have a "break before make" isolating breaker, your on the power company power OR gen power, AND NEVER THE TWO SHALL MEET!!!
Also are inverters, very popular in countries with substandard electrical grids. In essence golf cart batteries wired in series to create a large battery bank, run into an inverter which creates 240/120 VAC. to run your house, there is seamless transfer safety devices, growing in popularity here in FL. where the power cuts out and the inverter takes over so yo don;t even see a blink.
Regardless, who needs a 3 phase Generator??? What are you going to run with that?? Your Dryer & Stove, even hot tubs are 240 dual phase... L1 L2 N G thats it...
Three phase is L1 L2 L3 NO neutral and ground. 208 3ph is no joke, and you need to have a freq meter to maintain 60Hz here in the US or you will blow your appliance whatever up...
You must have a bad ass big screen for 3ph, I worked on the Princess of Mariana over 200 ft of floating power. 4 155kw generators, all 480 3ph...
This will light your neighborhood, apt bldg. and/or small community. Unless your running some serious heavy equip. 3ph is not practical..