Abstract :
Section 1 deals with the electrical design of open-circuit windings on the high-voltage machines used in connection with arc lamps in series; and the Brush open-circuit generators. The small hand-driven generators used in insulation-testing sets are also mentioned. Attention is drawn to the fact that interpoles were not introduced before these designs were superseded. Closed-circuit windings are dealt with, and it is pointed out that ring windings have gone out of use except for the special cases mentioned. The drum winding is then discussed. Section 2 deals with mechanical design. Section 3 treats of the effect of the number and dimensions of the core slots in relation to various aspects of the design. Attention is drawn to the effect on commutation of slots containing coils of various numbers of turns. Mention is made of the points to be noted in selecting the number of slots and coils. Section 4 deals with limiting factors in design. Section 5 shows how the ratio of diameter to length of armature for the minimum inductance of coil is deduced, and draws attention to the loss due to inductance. Section 6 treats of the effect of coil pitch on both commutation and armature reaction. General formulae are given for the period of commutation. Section 7 discusses special connections and their use in increasing the number of commutator bars, and draws attention to the factors limiting the output of direct-current machines. Section 8 deals with the factors affecting the electrical balancing of windings. Section 9 discusses windings for special purposes.
