Synchronization ofalternatormeansconnecting an alternator into gridin parallel with many other alternators, that is in a live system of constant voltage and constant frequency. Many alternators and loads are connected into a grid, and all the alternators in grid are having same output voltage and frequency (whatever may be the power). It is also said that thealternatoris connected to infinite bus-bar.A stationary alternator is never connected to live bus-bars, because it will result in short circuit in the stator winding (since there is no generated emf yet). Beforeconnecting an alternator into grid, following conditions must be satisfied:

Equal voltage: The terminal voltage of incoming alternator must be equal to the bus-bar voltage.

Similar frequency: The frequency of generated voltage must be equal to the frequency of the bus-bar voltage.

Phase sequence: The phase sequence of the three phases of alternator must be similar to that of the grid or bus-bars.

Phase angle: The phase angle between the generated voltage and the voltage of grid must be zero.