Introductory material

Essential parts of an alternator—field magnets—methods of excitation: self-excited, separately excited, compositely excited—magneto—construction of stationary magnets—revolving field—slip rings—spider for large alternator—provision for shifting armature to give access to field—armatures—core construction—advantages of slotted core armatures—armature windings—classification: revolving and stationary windings—half coil and whole coil windings—concentrated or uni-coil winding; features; waveform—distributed or multi-coil windings: breadth of coil, partial and fully distributed coils—the Kapp coefficient—general equation for voltage—wire, strap, and bar windings—condition, governing type of inductor—coil covering—single and double layer multi-wire inductors and methods of placing them on the core—insulation—core stamping—single and multi-slot windings—- arrangement in slot of two layer bar winding—table of relative effectiveness of windings—single phase windings—advantage of half coil winding—two phase windings—shape of coil ends—three phase windings—shape of coil ends—kind of coil used with three phase windings—grouping of phases—two phase star connection—two phase mesh connection—three phase star connection—winding diagrams with star and Δ connections—three phase Δ connection—three phase winding with "short" coils—three phase lap winding star connection—three phase wave winding star connection—output of star and delta connected alternators—gramme ring armatures showing three phase star and mesh connections with direction of currents in the coils—features of star connection—characteristics of delta connection—proper ends to connect to star point—determination of path and value of currents in delta connection—points to be noted with Y connection—diagram of Y connection with return wire—chain or basket winding—skew winding—fed-in winding—imbricated winding—spiral winding—mummified winding—shuttle winding—creeping winding—turbine alternator winding: how the high voltage is obtained with so few poles; table of frequency and revolutions—turbine alternator construction—form of armature generally used—two pole radial slot field—parallel slot field—difficulty experienced with revolving armatures—how the field design is modified to reduce centrifugal force—examples of revolving fields.