PUMP 4343866 - Caterpillar

Illustration 1 g03869299
Machine General Information
The machine is equipped with a standard 70 kW switched reluctance generator. The generator provides power to operate the electric screed heaters and the optional accessory power inverter. The generator is driven directly by the engine.Electrical Power Generation
Illustration 2 g06033174
Generator Operation
(1) Stator
(2) Rotor
(3) Stator pole
(4) Stator winding
(5) Rotor pole
(6) Generator phase currentsRotor (2) of the switched reluctance generator is driven by the engine. Stator (1) is attached to the generator housing and remains stationary. The rotor and the stator are made of steel laminations with symmetrical and equally spaced salient poles. The salient poles on rotor (5) extend outward toward the stator. The salient poles on stator (3) extend inward toward the rotor. When the poles on the rotor and stator are aligned, a thin air gap separates the poles.Stator (1) includes copper coils (4) wound around each pole. The coils are electrically connected into three separate groups, each of which forms a phase.Rotor (2) has no magnets, windings, or brushes. Torque is transferred to (or from) the rotor through the principle of magnetic reluctance. In a magnetic field, magnetic flux will follow the path of least magnetic reluctance, analogous to electric current following the path of least resistance.In a switched reluctance motor, when a phase is energized, a magnetic field is created. Rotor poles (5) are pulled into alignment with this field to create the path of minimum reluctance. In the case of a generator, the torque from the engine pulls the rotor out of alignment with the energized phase. This movement increases the reluctance, causing more current to flow through the coils. The energy generated in the coils during this stage is greater than the energy put into the coils to create the initial magnetic field. The result is a net increase in electric energy.Each excitation cycle of a phase creates a single pulse of current on that phase. Combined generator phase currents (6) produce a continuous series of current pulses. The pulsed direct current (DC) is smoothed out by the capacitor contained within the inverter, resulting in a stable voltage output on the DC bus.