Patent GB-190307716-A (GB)
Title: Improvements in Means for Controlling the Working of Periodically Operating Electric Machinery
Inventor: JOHNSON JAMES YATE
Filed: 1903-04-02
Granted: 1904-04-02
Abstract: 7716. Johnson, J. Y., [Elektrizitõts Akt.- Ges. worm. W. Lahmeyer & Co.]. April 2. Dynamos and motors combined for transmitting power; motors, controlling.-Relates to arrangements for use in connection with intermittently-operated electric machinery, such as winding-machinery at collieries &c. Buffer or compensating machines are employed to store energy during the stopping period. Preferably the compensating - machine gives a counter-electromotive force at starting which is reduced and reversed as the motor speeds up. Fig. 1 shows one arrangement, in which D, G is a motor-generator driven from alternating- current mains, P is the compensating-machine provided with an energy-storing mass S, M the motor, R', R<2> resistances in the fields which are supplied from a separate exciting-source, and u a change-over switch. When the switch u is on the contact 1, the machine P is driven and energy stored. To start the motor M, the field circuits of the generator G and compensating-machine P are broken, and the switch u moved to the contact 2. On gradually exciting the fields, the motor starts, the machine P giving up its energy according to the potential supplied. In a modified arrangement, Fig. 2, the machine P and the generator may be connected to oppose one another at starting, and then, by diminishing the excitation of the field of the machine P, the motor M is started, and finally the machine P run to assist the generator. The potential applied to the motor M may be varied by varying a resistance in the armature circuit, and such resistance may be varied simultaneously with a resistance in the field of the machine P. In another arrangement, Fig. 4, a variable potential may be supplied to the machine P by means of an auxiliary machine Z coupled to it and driven electrically or otherwise. When driven electrically, the field n may be varied by a regulator R<3>, which can be operated by hand or automatically ; or the excitation of the machine Z may be suitably compounded. In order to lessen loss in the resistances, an additional machine may be employed to introduce a counter-electromotive force at starting, which electromotive force is gradually diminished as the speed rises, and may finally be reversed in sign and added to that of the mains. The energy - storing mass may be mounted directly on the motor M, as in the case of rolling-mills, or it may be mounted in connection with the motor-generator. Fig. 6 shows such an arrangement. The generator is driven by a three-phase motor D, and is provided with an energy-storing mass. An additional machine A<1> to give a counter-electromotive force may be switched in at starting. The armature of the three-phase motor is not closed on itself, but is connected to the armature of a motor-generator m, d having two fields n<1>, n<2> connected as shown. The fields are so proportioned that the speed of the armature d can be controlled, and consequently that of the motor D. Various other arrangements of the machines and of their interconnections are described in the Specification for varying the potential supplied to the motor and utilizing the stored energy, and in place of a motor-generator a transformer with a single winding or a stationary transformer may be employed. Fig. 12 shows another modification, in which the regulator R<3> for varying the field of the additional machine Z or the compensating-machine P is controlled by a centrifugal governor R<4> connected to the energystoring mass and acting through epicyclic gearing controlled by an electromagnet E. The electromagnet has two windings, one in series and the other in parallel with the circuit of the motor M. The governor R<4> may turn the lever of the regulator R<3>, while the magnet E rotates the contacts of the regulator.