TABLE OF CONTENTS GUIDE NO. 2.

THE ARMATURE 221 to 228

Definition—how continuous current is obtained—type of armature—comparison ring and drum armatures—why drum armature is the prevailing type—disc armatures—why disc armatures were abandoned.

ARMATURE WINDINGS 229 to 256

Preliminary considerations—winding diagrams and winding tables—lap and wave winding—angular pitch or spread of drum coils—parallel or lap winding—series or wave winding—double-windings—Siemens winding—objection to Siemens winding—chord winding—multiplex windings—number of brushes required—number of armature circuits—equalizer rings—drum winding requirements.

THEORY OF THE ARMATURE 257 to 282

Current distribution in ring and drum armatures—connection of brushes—variation of voltage around the commutator—cross magnetization; field distortion—remedies for field distortion—angle of lead—demagnetizing effect of armature reaction—effect of lead—eddy currents; lamination—remedy for eddy currents—magnetic drag on the armature—smooth and slotted armatures—comparison of smooth and slotted armatures—magnetic hysteresis in armature cores—core loss or iron loss—dead turns—friction.

COMMUTATION AND THE COMMUTATOR 283 to 302

Period of commutation—commutating plane—normal neutral plane—neutral plane—plane of maximum induction—commutation—position of the brushes—sparking—effect of self-induction—construction of commutators—points relating to commutators—types of commutator.

BRUSHES AND THE BRUSH GEAR 303 to 320

Classification—gauze brushes—wire brushes—strip brushes—carbon brushes—adjustment—comparison of copper and carbon brushes—size of brushes—number—contact angle of brush— brush contact—drop in voltage at brushes—brush holders—brush rigging—multipolar brush gear.

ARMATURE CONSTRUCTION 321 to 348

Parts—shaft—core—slotted core—core laminations—core bolts—attachment to shaft—insulation of core discs—teeth—advantages and defects of slotted armatures—slotted cores; built up construction—ventilation—insulation of core—armature windings—construction of inductors—objection to copper bars—various windings: hand winding—evolute or butterfly winding—connectors—barrel winding—bastard winding—former winding—former coils—peculiarity of evolute coil—"straight out" coil—coil retaining devices—driving horns.

MOTORS 349 to 388

Definition—principles—propelling drag—essential requirements of construction—the reverse electromotive force—hydraulic analogy—action of current supplied to motor—armature reaction in motors—method of starting a motor— classes of motor; series, shunt, and compound—power of a motor—brake horse power—mutual relations of motor torque and speed—speed regulation—series parallel controller—interpole motors.

SELECTION AND INSTALLATION 389 to 406

General conditions governing selection—construction—efficiency—adaptation of series and shunt motors—location—foundations—erection of dynamos and motors—connecting up dynamos—marine generating set—belt clamp—belt lacing—belt speed—points relating to belts—gear drive—friction drive—electrical connections.

AUXILIARY APPARATUS 407 to 430

Switches—switch classification and construction—difficulty encountered in opening the circuit—various switches: knife, snap, and quick break types—fuses—circuit breakers: maximum, minimum, reverse current, maximum and reverse current, no voltage breaker—discriminating cut out—time limit attachments—rheostats—starting boxes—switchboards.