I may be wrong here......
But I've been around Electricity for a long time.
Have Never seen a device that does phase conversion.
A Building site or home will either have Three Phase or Single Phase Power Available
BUT...A portable (Hired) generator could be "three phase" and you could use any one of those phases individually or all three phases.
I have 3 Phase supply to my house!
But I use 230 volt Single Phase for appliances.
My Bore Pump uses a 3 Phase Motor,
(so with a voltmeter it would read about 440 vAC to the pump motor).
Some Further Info:
A GENERATOR is basically a motor used the opposite way. Rotate a motor and it Generates.
The Phases refer to the THREE Windings in the supplying generator in your suburb.
A Large Magnet passes each winding in sequence giving you the three ripples in the supply.
Our houses can choose to have 1 Phase or Three Phases from the street when you set up your electric supply.
So... to confirm, look at the wires on the supply poles to the premises. Usually three in our area (Oz)
Most people are not aware that a car Alternator is actually three phase. The Rotor is the magnet that rotates.
The only difference with an Alternator is that each "Phase" is connected to 2 Diodes (6 total) to convert the three phase to DC to charge the vehicle.
The Regulator controls the voltage to the Rotor, thereby controlling the output.
So.... An Alternator could in theory supply 3 Phase in a mobile generator. Custom Made. Constant speed would determine the frequency of 50Hz or 60Hz.
Not sure what country you are in
Hope this Helps or gives you food for thought!
Three phase electric power