Power Tech Generators PTS-25 Operator's Manual page 23

The rotating field assembly consists basically of four members: 1) the shaft assembly, 2) the
core assembly, 3) the field coil damper windings, and 4) balance lugs to provide a high degree of static
and dynamic balance.
The core assembly consists of a quantity of thin steel plates compressed and fastened together to
form a single laminated assembly. The field windings are wound around this assembly.
Field coils of heavily insulated wire are "wet" wound directly onto the poles. Field coil leads are
brought out to the rectifier assembly for connection to the source of DC excitation voltage.
The rotor assembly is precision balanced to a high degree of static and dynamic balance.
Although the balance will remain dynamically stable at speeds in excess of the design frequencies, the
prime mover should be adequately governed to prevent excessive over speed. High centrifugal forces
created by excessive over speed may damage the rotor windings and field coils.
The generator rotor assembly is suspended on a shielded factory lubricated ball bearing. A visual
inspection of the bearing is recommended at typical service intervals. If signs of abnormal wear
or leakage are observed, the bearing should be replaced. Never use liquids of any kind to clean the
generator end and bearing.
The stator assembly consists of laminations of steel mounted in a rolled steel frame. Random
wound stator coils are fitted into the insulated slots.
ROTATING FIELD ASSEMBLY (ROTOR)
CORE ASSEMBLY
FIELD COIL
BALANCE
BEARING
STATOR ASSEMBLY
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