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Generator separately excited by battery Self exciting generators Series on left, shunt on right. A shunt generator is a type of electric generator in which field winding and armature winding are connected in parallel, and in which the armature supplies both the load current and the field current for the excitation (generator is therefore self excited).
The winding material must have a low resistance, to reduce the power consumed by the field coil, but more importantly to reduce the waste heat produced by resistive heating. Excess heat in the windings is a common cause of failure. Owing to the increasing cost of copper, aluminium windings are increasingly used. [citation needed]
In a "lap" winding, there are as many current paths between the brush (or line) connections as there are poles in the field winding. In a "wave" winding, there are only two paths, and there are as many coils in series as half the number of poles. So, for a given rating of machine, a wave winding is more suitable for large currents and low voltages.
a shunt, the simplest design, uses the main winding for the excitation power; an excitation boost system (EBS) is a shunt design with a separate small generator added to temporarily provide an energy boost when the main coil voltage drops (for example, due to a fault). The boost generator is not rated for permanent operation;
The speed of a DC motor can be increased by field weakening. Reducing the field strength is done by inserting resistance in series with a shunt field, or inserting resistances around a series-connected field winding, to reduce current in the field winding. When the field is weakened, the back-emf reduces, so a larger current flows through the ...
Shunt winding was used experimentally, in the late 19th century, [8] but was impractical owing to problems with commutation. Various schemes of embedded resistance, inductance, and antiphase cross-coupling were attempted to reduce this. Universal motors, including shunt wound, were favoured as AC motors at this time as they were self-starting. [4]
Parts: (A) commutator, (B) brush, (C) rotor windings, (D) stator (field) windings, (E) brush guides, (F) electrical connections. A commutator is a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit.
A compensation winding in a DC shunt motor is a winding in the field pole face plate that carries armature current to reduce stator field distortion.Its purpose is to reduce brush arcing and erosion in DC motors that are operated with weak fields, variable heavy loads or reversing operation such as steel-mill motors.