GB194731A - Improvements in and connected with dynamo electric machines - Google Patents

Abstract

194,731. Soc. Anon. Electrolabor, (Assignees of Poirson, E. J. F., and Escouflaire, G. A.). March 13, 1922, [Convention date]. Armatures and field magnets; machines with two or more armatures; rotary converters and motor-generators.-A high-speed dvnamo giving a voltage practically free from variations or harmonics particularly for use in telephony and wireless telephony, has a very small air gap, an armature mounted on ball bearings and constructed with an odd number of nearly closed inclined narrow-mouthed slots e which are wound with a high space factor, and supple metallic brushes making tangential contact with the commutator. The field-magnet windings, which may be shunt or series or compound, are of enamelled wire. The armature winding is divided into a large number of sections and the windings are impregnated with insulation during winding, whereby voltages from 1000 to 1500 volts may be obtained from small machines. The armature may be wound with several windings connected to separate commutators c<1>, c<2>. In the case of two windings one may be a low-tension winding, e.g. for 8 volts, and the other a high-tension winding, e.g. for 600 volts. In order to suppress higher harmonics, the armature may be constructed in two identical sections e<1>, e<2>, Fig. 3, insulated from each other, and each provided with a commutator. The two sets of brushes are connected in series and the field winding i is connected across the outside terminaLs. By listening with a telephone t the brushes can be adjusted so that the harmonics in the windings are in opposition. The machine may also be provided with slip-rings and may function as a current transformer.