Patent GB-190902520-A (GB)
Title: Regulating System for Alternate-current Installations.
Inventor: HEYLAND ALEXANDER
IPC: H02K17/30
Filed: 1909-02-02
Granted: 1910-02-02
Abstract: 2520. Heyland, A. Feb. 3, 1908, [Convention date]. Regulation, automatic systems and apparatus for ; systems depending on the u s e of auxiliary machines; equalizing load. - The variations of potential produced by the operation of working or load - carrying motors connected to an alternating- current system are automatically regulated by devices combined with these motors. As shown in Fig. 1, an auxiliary machine e is connected to the mains, and its excitation is varied, so as to compensate for potential variations produced by starting the motor a, by mechanically coupling the rotor resistance r to the field resistance w. The machine e may be of any suitable type, a synchronous motor running light being shown in Fig. 1 ; or the generator of the system may be used. The current in the field of the auxiliary machine may be varied in any other way, for example by means of a machine driven by the working motor, by operating the rheostat w by currents developed in the working motor, or by its terminal voltage ; the speed, acceleration, or other property dependent on the operation of the motor may be employed. Where the working motor is fed through a synchronous motorgenerator, the primary element of this set may be used in place of the machine e, avoiding the use of a fly-wheel for the purpose of steadying the voltage and the consequent losses. The voltage drop may even be over-compensated and the mean power factor thus kept very high. Such a system used with winding or rolling-mill plants entails a regulation of supply potential proportional to the secondary circuit voltage or current respectively. This is effected by connecting the rotor of the synchronous motor in parallel or in series respectively with the direct-current system, part of the excitation being derived from the usual separate source if desired. Fly-wheel effects may, however, be retained if an asynchronous motor-generator is used, much smaller fly-wheels than usual being necessary. Fig. 7 shows a modification in which such an asynchronous motor-generator set is used. The regulation is in this case effected by a synchronous machine e connected to the network, and, if the supply be single-phase, generating the extra current for the polyphase motor a. The field of the machine e is partly supplied from the usual exciting current source as shown, but the circuit of the direct-current working motor c is connected in parallel to the field of the auxiliary machine to effect the regulation. An exciter f may be coupled to the machine e. A regulating effect may be obtained in other arrangements by coupling the exciter f to the motor-generator or to the working motor. The asynchronous motor a may be made to supply the regulating effect by connecting its rotor with the armature of the working motor by means of slip-rings on the latter, or by connecting the former to the stator of an auxiliary machine d, Fig. 9, coupled to the working-motor, the field of the machine d being connected in parallel with the working motor circuit. Another method consists in fitting the generator b, Fig. 9, with slip-rings from which a regulating-current is supplied to the rotor of the machine d coupled to the working motor and provided with slip-rings. A further development of this last arrangement is shown in Fig. 11. The slip-rings of the generator b are connected to the stator of another auxiliary machine e, the rotor of which is connected, together with the stator and an asynchronous machine d coupled to the working motor, to the rotor of the primary motor a, to supply the regulating effect. If the machines a and b in this arrangement have the same number of poles, and the auxiliary machine e is arranged so that its stator and rotor rotate in opposite directions, the rotor shaft will revolve at a constant speed and an exciter f may be driven therefrom. A further modification of the arrangement shown in Fig. 7 is also described in which the working motor is coupled to a machine connected to the slip rings of the motor a as shown in Fig. 11. Those modifications which emply two inter-connected motor-generator sets permit of either set a, b or c, d being used to supply mechanical work, the efficiency being greater when the former set is so used. In this case, the motor a may be a single-phase machine, a change-over switch in the high-tension leads to this motor being obviated by placing such a switch in the rotor circuit of the machine.