Page 80 - Apprentice Manual_Neat

Section 3: Generators/Alternators

S3-Q55.) Which of the following is NOT a component of a brushless generator?

a.) Exciter field
All generators must have a field.
b.) *Slip rings
Correct. Since it is brushless, slip rings would have nothing to transfer energy to, so there is no
need for slip rings.
c.) Rotating diodes
Part of the exciter is the rectifier which is composed of diodes. Since the field is created through
induction, the diodes must be located on the rotor.
d.) Main rotor
Generation could not take place without the rotor.

S3-Q56.) On a 2-pole generator, how many revolutions are required to produce one complete sine-wave?

a.) *1 full revolution
Correct. Having two poles means that the coil only rotates in one positive direction and one
negative direction with each rotation. Since each alternation consists of one positive pulse and
one negative, this corresponds.
b.) 2 full revolutions
This would yield two complete sine-waves. The coil would rotate from positive to
negative two times and there is only one positive and one negative alternation in each sine-wave.
c.) ½ revolution
This would only yield either the positive pulse or negative pulse. The coil would not make it through
both positive and negative.
d.) 4 revolutions
This would yield for complete sine-waves. The coil would rotate from positive to negative four times
and there is only one positive and one negative alternation in each complete sine-wave.

S3-Q57.) Generated voltage is a function of what?

a.) Stator configuration
To a minor degree there is some configuration considerations of the stator. However, the stator is
usually selected for the specific application and configuration is not a concern.
b.) Prime mover RPM
RPM determines frequency.
c.) *Magnetic strength of the main rotor
Correct. Flux density is the key to generation. The greater number of flux lines, the more
voltage that can be induced. The only consideration is the permeability of the material (how
well it conducts magnetic flux) and saturation (the maximum amount of flux it can conduct).
d.) Diode polarity
Diodes have an anode and a cathode which are determined at manufacture. Polarity does not change.

EGSA Apprentice Certification Program Study Guide - Page 72