Brochure

3
Construction
Frame
The stator frame is made of welded
steel construction and manufactured
with thick steel plates to prevent
distortion during operation. Robust
and rugged, these frames are
designed to withstand the mass of
a stator core, bending stresses and
deections. The frames are designed
to minimize vibrations and noise
levels. The frame bore is machined to
ensure a uniform air gap between the
rotor and stator, thereby minimizing
the unbalanced magnetic pull. These
frames are designed to withstand the
extreme stresses due to short circuits.
Each machine is designed to be
assembled on a robust concrete
foundation or steel base. A minimum
of four lifting points is provided in the
generator to facilitate this process.
Larger or heavier machines, which
are shipped disassembled, are
reassembled over the foundation
at the site, as a part of the eld
installation process.
The frame is fabricated from structural
steel plates to ensure an extremely
robust and rigid support structure. The
generator can be designed for open
enclosure and totally enclosed water-
to-air cooled. The exciter and rectier
hub are mounted at the non-drive
end (NDE) enabling easy access for
maintenance purposes.
Stator Core
The stator core assembly consists of
segmented and insulated laminations
of cold-rolled low-loss silicon steel,
clamped between substantial side
plates. Laminations are stacked up
with a controlled burr in order to
ensure minimal losses. Lamination
steel is selected based on project
requirements. The core is built inside a
structural cage, which is then inserted
into the frame and attached through
weldments. Steel I-beam spacers
spot welded to low carbon steel
laminations form radial ventilation
ducts along the core length. When
core building is complete, the whole
assembly is clamped under pressure
with studs. The nuts and compression
plates are welded in place while
maintaining pressure.
Laminated Poles
The rotor has laminated poles tted
with strip or wire wound
eld coils and supplied with an
amortisseur winding on the
outer pole face.
Laminated Spider
The rotor spider is made of thin
laminations, clamped with axial
studs. According to design needs,
there are axial holes to improve the
air ventilation through the rotor. The
laminated poles are attached to the
spider with dovetails.
Solid Spider
The rotor spider and shaft are
obtained from a one-piece machined
carbon steel forging. According to
design needs, there are axial holes to
improve the air ventilation through
the rotor. The laminated poles are
xed on the spider by using dovetails
on the pole bottom.
Rim Spider
The rim is made of forged steel.
The rim is shrunk on to a large web
that is attached to the shaft by
means of a hub and a key, then pole
bodies are attached to the rim via a
number of radial bolts.
Two axial or radial fans (according
to design characteristics) are
mounted on the shaft to provide
airow to maintain the machine
temperature within the limits
specied. The fans are used to
provide double-ended ventilation,
helping ensure an even temperature
distribution across the eld and
stator windings.
Rotor
Three types of rotor construction
can be utilized in this product line:
a laminated spider with dovetailed
poles, a rim spider with bolted poles, or
a solid spider with dovetailed poles.
Rotor with shaft-mounted out board exciter