Three-phase generator uses three-phase AC power supply, because of the three-phase AC their phase difference is 120°. When the stator winding is connected to the three-phase alternating current, a rotating magnetic field will be generated in the stator. Rotating magnetic field cuts the rotor winding, then the rotor winding will produce inductive current, the inductive current will be affected by the electromagnetic force in the rotating magnetic field, so it will rotate up.

Three-phase generator uses three-phase power supply, and their phase difference is 120°. We can simply understand that the three-phase generator is equivalent to three people standing at three different angles to push the rotor. Single-phase generator adopts single-phase power supply and capacitance, and the phase difference between main and secondary coils is 90°. We can simply understand that a single-phase generator is equivalent to two people standing at two different angles to push the rotor. Therefore, a three-phase generator with the same power has a greater torque (rotational force) than a single-phase generator.

Generally, if there is a three-phase power supply, try to use a three-phase generator, because the same power three-phase generator is smaller than a single-phase generator, light weight, small noise, low price, high torque advantages. Finally, why do Marine generators use three-phase? That is because the ship's electricity is basically three-phase, three-wire system, and the power grid is well insulated to the ground, so that when the crew accidentally touches any wire of the power grid, there will be no accident of electric shock. When single-phase grounding occurs, short circuit is not formed and the normal operation of electrical equipment can still be maintained. The two phases are not the same, not a single term can be missing.