The Three-Phase Generator

Three-phase generators have three sets of windings and thus produce three ac voltages instead of one. The three-phase generator has three induction coils placed 1200 apart on the rotor (armature). Since the three coils have an equal number of turns, and each coil rotates with the same angular velocity, the voltage induced across each coil will have the same peak value, shape, and frequency.

The Y-Connected Generator

If the three terminals (denoted N) of the three windings are connected together, the generator is referred to as a Y-connected three-phase generator. The point at which all the terminals are connected is called the neutral point. If a conductor is not attached from this point to the load, the system is called a Y-connected, three-phase, three-wire generator. It the neutral is connected, the system is a Y-connected, three-phase, four-wire generator.

Phase Sequence (Y-Connected Generator)

The phase sequence can be determined by the order in which the phasors representing the phase voltages pass through a fixed point on the phasor diagram if the phasors are rotated in a counterclockwise direction. The phase sequence can also be described in terms of the line voltages. In this case, the sequence can be determined by noting the order of the passing first or second subscripts.

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