142 Electrical Power Systems Technology
Find: the amount of induced voltage in each conductor.
Solution:
Vi = B × L × v
= 0.8 × 0.5 × 60
Vi = 24 Volts
SINGLE-PHASE AC POWER SYSTEMS
Electrical power can be produced by single-phase generators, com-
monly called alternators. The principle of operation of a single-phase alter-
nator is shown in Figure 6-3. In order for a generator to convert mechani-
cal energy into electrical energy, three conditions must exist:
- There must be a magnetic field developed.
- There must be a group of conductors adjacent to the magnetic field.
- There must be relative motion between the magnetic field and the con-
ductors.
These conditions are necessary in order for electromagnetic induc-
tion to take place.
Generator Construction
Generators used to produce electrical power require some form of
mechanical energy. This mechanical energy is used to move electrical con-
ductors through the magnetic field of the generator. Figure 6-3 shows the
basic parts of a mechanical generator. A generator has a stationary part
and a rotating part. The stationary part is called the stator, and the rotating
part is called the rotor. The generator has magnetic field poles of north and
south polarities. Also, the generator must have a method of producing a
rotary motion, or a prime mover, connected to the generator shaft. There
must also be a method of electrically connecting the rotating conductors
to an external circuit. This is done by a slip ring/brush assembly. The sta-
tionary brushes are made of carbon and graphite. The slip rings used on
AC generators are made of copper. They are permanently mounted on the
shaft of the generator. The two slip rings connect to the ends of a conductor
loop. When a load is connected, a closed external circuit is made. With all of
these generator parts functioning together, electromagnetic induction can
take place and electrical power can be produced.