Basic electrotechnical units and theory
93
this simple arrangement produces very bumpy d.c.
When coil wire rotated inside magnetic field shown Fig. generator dynamo. 4.c. Such waveform has the characteristics displayed Fig.
The generated alternating supply the power station transformed up
to 132,000 more, for efficient transmission along the National Grid
conductors. output.5, a
voltage induced the coil.8. 4. output.
Cathode
ray
oscilloscope
Rotation
N
S
Carbon brush
Commutator
FIGURE 4. Similar the unidirectional bat-
tery supply shown Fig.
One the reasons for using alternating supplies for the electricity mains
supply because can very easily change the voltage levels using a
transformer which will only work a. (see Fig.c. 4.7.6
Simple d.
Alternating current theory
The supply which obtain from car battery unidirectional d. supply.7).c. 4.
. practical
machine, the commutator would contain many segments and many wind-
ings produce smoother d.c.c.
Most electrical equipment makes use alternating current supplies, and
for this reason knowledge alternating waveforms necessary for all
practising electricians. sup-
ply, whereas the mains electricity supply alternating a. The induced voltage follows mathematical law
known the sinusoidal law and, therefore, can say that sine wave has
been generated
