Advantages of Stationary Armature Winding in Alternator

The field winding of an alternator is placed on the rotor and is connected to DC supply for producing the magnetic flux through slip rings/ brush-less excitation.

The 3 Ø armature winding is placed in the stator. This have following advantages:

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1. \mbox{Copper Loss} \propto I^2 \cdot R will increase.

Because in 210 MW unit the excitation current(2600 A) is very small the the alternator full load current(9050 A).

I = 210 x 10^6 / √3 x 15750 x .85

=9056 A

This much current will not possible to come out through slip ring/ brush

*2. More no of brush will required for 3Ø four wire STAR-CONNECTIONS.

3. The Output Voltage will reduced by the reduce of no of turns of conductor or Area.

4. Due to simple and robust construction of the rotor , Higher speed of rotating rotor is possible

5. The stationary 3-Phase armature can be directly connected to load without large unreliable slip ring and brushes.