(2) When the voltage increases above normal enough current will flow
through the relay to energize it. When it energizes, the field circuit is opened
cutting off the current. The magnetic flux decreases lowering the output voltage.
(3) When the output voltage decreases, the current through the relay is
reduced, thus applying less magnetic force to the spring-loaded contact. When the
magnetic force of the relay coil is less than the force of the spring, the contact
will once again close. Upon the closing of the relay contact, current once again
flows through the field winding, which will cause the output voltage to increase.
(4) The opening and closing of the relay contacts are continuous; so,
during normal operation, they vibrate. The rate of switching will vary according
to the speed of the generator, thereby regulating the output voltage. The rate can
be as low as 10 times per second and as high as 7,000 times per second.
d. There is one thing wrong with the circuit in figure 5 and that is, when
the vehicle is stopped, the battery will be connected to the field winding
(1) Since a field winding can draw from 1 ampere to 10 amperes of
current, depending on the size of the generator, it could run the battery down
while the vehicle is sitting overnight.
OS 010, 5-P4