GB191014851A - Improvements in Controllers for Electric Motors. - Google Patents

Abstract

14,851. Adams Manufacturing Co., Cutler Hammer Manufacturing Co.]. June 20. Master control systems; systems for continuous-current Motors only.-Relates to motorcontrollers in which a number of automatic switches controlling steps of armature resistance are each provided with an automatic relay preventing its operation during excessive current flow in the motor, and in which the relays are arranged in series and are adapted to operate successively to cause the successive operation of the resistance - controlling switches. The connexions and relays are so arranged that each resistance switch short-circuits its own relay upon operating. An interlocking switch prevents the operation of the resistance switches until the motor circuit is closed and the relays are in circuit. A hand switch 13 energizes a main switch 1, which establishes a circuit through the armature A, field F, resistances R<4>, R<3>, R<2> and the coils of relays 5, 6, 7 in series, and, by means of an interlocking switch 8, closes shunt circuits through the coils of the resistance-controlling switches 2, 3, 4 in parallel. Each of the latter circuits includes the contacts of one relay. These relays are all operated by the rush of starting-current, and prevent their corresponding resistance switches from operating. They are adjusted to close again in sequence as the motor current falls to different values. As each relay switch closes, it energizes its resistance switch, which, on operating, not only short-circuits its section of resistance but also the winding of its relay, these windings being put in parallel with the different sections R<2>, R<3>, R<4> of resistance, through the switch contacts 2, 3, 4 respectively.