Robin America RGX180 Service Manual page 22

The RG Series 1s the revolving armature type. and the RGX Series is the revolving field tk-pe. The differences between these
types and then features are described below. The constructron of the revolving armature t>-pe is shoxn in Fig. 5 -15. and that
of the revolvmg field type in Fig. 5 -16.
The basic operating principle of the generator is this. As a conductor moves in a magnetic flus (between poles S and S of a
magnet). a voltage is generated in the conductor and can be taken out as electric power. Generally. an electromagnet is used
for generators. The ele.ztromagnet consists of poles and field coils wound around them, and the poles become magnets as a
direct current runs through the field coils. The revolvtig armature type has static poles and a revolving armature which con-
sists ot' a conductor for taking electric power out. The revolution of the armature generates a voltage.
It was earlier explained that a conductor moves in a magnetic flux. Actually, howev-er. a relative speed between the two is
sufficient for generating a voltage. That is. a voltage can also be generated bl- rotating the magnet while keeping the con-
ductor still.
The revolving field type falls in the latter categor!-: The pole serving as an electromagnet rotates. and armature ivhich con-
sists
of
a conductor remains still.
The features of the revolving field type are as follows:
a)
b)
Cl
Only two slip rings
AS generator applications diversified! it became necessary for generators to meet increasingly varied conditions involv-
ing XC output. DC output, dual voltage, three-phase, and usefulness with induction motors. Accordingly. AC windings.
DC windings. auxiliary windings, etc. became necessary for generators. Because the revolving armature type takes elec-
rric power from the revolving part. it requrres as many slip rings as the number of winding output termmals. and this
increases the generator dimensions. The revolving field type is small in size because it requires only two slip rings <or
feeding a current to operate the electromagnet.
Easy maintenance
As man)- brushes as the number of slip rings are necessary. The revolving field type is easier to maintain than the re-
volving armature type because it has fewer slip rings and brushes than the latter.
Lightweight
The revolving armature type is heavT because it requires yokes to fix the poles and serve as tlus passage. The revolving
field type is light in %-eight because the stator and rotor can be made by laminating steel sheets of the same material.
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