Page 39 - Practical Power System and Protective Relays Commissioning

Generators and Motors: Theory and Testing Chapter | 4 35

4.3.3.6 Hydro-electric Energy
The fall of water onto a turbine (e.g., a natural waterfall or manmade dam)
causes a turbine to rotate and produce electricity.

4.4 SYNCHRONOUS GENERATORS: THEORY AND
CONSTRUCTION
A synchronous generator consists of a stator with stator winding, and rotor
with rotor field winding. When the current passes through the rotor winding,
this generates a rotating magnetic field.
This rotating field energizes the stator winding and generates an electro-
motive force (emf). The emf generates an AC current in the stator winding
as shown in Fig. 4.3.
Generator units can have rates between 250 and 800 MW, however high-
er units do exist with a rated voltage of between 16.5 and 27 kV and rated
current of 10,000 20,000 A.
The components of turbogenerators are:
1. Stator: stator frame, stator core, stator winding, end cover, bushings, and
generator terminal box.
2. Rotor: rotor shaft, rotor winding, rotor ring, and field connection.
3. Excitation system: pilot exciter, main exciter, and diode wheel.
4. Auxiliaries: bearings, cooling system, and oil supply system.

FIGURE 4.3 Synchronous generator construction.