Nidec LSA 52.3 - Rotor; Pole Wheel (Laminated); Excitation Armature; Fan (Machines: IC 0 A1)

Electric Power Generation
Installation and maintenance
5382 en - 2022.11 / h
LSA 52.3 / LSA 53.2 / LSA 54.2
Industrial Range Alternators
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7
2.2 ROTOR
2.2.1 Pole wheel (laminated)
The pole wheel is produced by stacking cut laminations to
reproduce the profile of the pole (item 1).
Stacking of steel laminations is completed at each end by
high electrical conductivity laminations (item 2).
In order to allow the alternators to run in parallel, and so as
to ensure stability, bars with high electrical conductivity are
inserted in holes passing through the poles from one end to
the other. These bars are welded together with the end
plates so as to obtain a complete cage (or LEBLANC
damper cage).
The winding (item 4) is wound on the pole and then
impregnated.
The winding is made of insulated copper wire of
rectangular cross-section and high electrical conductivity.
Aluminium plates (item 5) are pressed against the winding
acting as dissipating radiators and ensuring excellent
wedging of the coils.
Retaining bars (item 6) on each pole protect the heads of
the coils from centrifugal forces.
The wound pole wheel is heated and shrink fitted onto the
shaft.
2.2.2 Excitation armature
The excitation armature is made by stacking magnetic steel
laminations. These steel laminations are held in place by
rivets.
The excitation armature is keyed and heat-shrunk onto the
shaft.
The windings are enamelled copper wires, class "F"
insulation (or "H", depending on the customer's request or
size of the machine).
2.2.3 Fan (machines: IC 0 A1)
The synchronous machine is characterized by a self-
ventilation system. A centrifugal fan is mounted between
the revolving field coil and the front bearing.
Air intake is at the rear of the machine and the exhaust at
the front.
The fan consists of a hub, which is keyed and heat-shrunk
onto the shaft. The fan is made of welded steel sheet,
attached to the hub by screws. Ventilation is obtained by
means of inclined blades. The air is exhausted by
centrifugation. The air inlet and outlet must remain free
during operation.
2.2.4 Rotating diode bridge
The rectifier bridge, comprising six diodes, is placed at the
rear of the machine. The rotating bridge is made of
fibreglass with a printed circuit to connect the diodes
together. This bridge is supplied with alternating current by
the excitation armature and supplies direct current to the
pole wheel. The diodes are protected against over voltage
by rotating resistors, or by varistors. These resistors (or
varistors) are mounted in parallel with the pole wheel.
+
-
1
2
3
1 - Field
2 - Rotating resistors / varistors
3 - Exciter armature
The 2 radiators of the diode bridge are connected to the
pole wheel.
1 - Radiator 1
2 - Radiator 2
The diode fastening screws must be tightened to the
correct torque.
CAUTION:
THE ROTATING DIODE FASTENING SCREWS MUST
BE TIGHTENED USING A TORQUE WRENCH
CALIBRATED TO THE RECOMMENDED TORQUE.
2.2.5 Balancing (single fan machine)
The complete rotor was balanced as per the ISO8221
standard to achieve a residual imbalance of less than:
1
2
2
2
3
4
5
6
Radiator 2
Radiator 1