Patent GB-190808522-A (GB)
Title: Improvements in Turbo-electric Generator Systems.
Inventor: BERG ERNST JULIUS
Filed: 1908-04-16
Granted: 1908-11-19
Abstract: 8522. Berg, E. J. April 20, 1907, [date applied for under Section 91 of Patents &c. Act, 1907]. Elastic-fluid turbines. - Two turbines, each comprising two rotors mounted upon independent shafts, are combined with three dynamos to form a station plant. The turbines employed are preferably of the axial-flow type comprising two oppositely rotating rotors 1, 2, Fig. 1, furnished with buckets 3 and mounted upon independent shafts 11, 12, which are preferably, but not necessarily, in exact alinement. Steam passes from a steam-chest 9 to nozzles 4, and after passing through the blades exhausts into a chamber 6. The shafts are packed with spring-pressed carbon rings 13. The turbines may be modified by providing each wheel with two or more rows of buckets with or without stationary intermediate buckets. Instead of causing the rotors to rotate in opposite directions, they may be made to rotate in the same direction by means of suitably shaped intermediate buckets. Alternatively, the turbines may be of the radialflow type. At a bucket speed of about 560 feet per second, it is stated that the primary rotor 1 will perform 70 per cent of the work and the secondary wheel 2 about 30 per cent. This inequality of torque is taken advantage of in arranging the generators. In one system, comprising two turbines 5, Fig. 2, working in series, and three dynamos 18, 19, 21, the two primary rotors are arranged on a common shaft and drive the dynamo 18, which is of the induction type, developing about 70 per cent of the total output. Each of the dynamos 19, 21 is of the synchronous type, and is driven by a secondary rotor and develops about 15 per cent of the total output. Steam enters a supply pipe 8, drives the left-hand turbine, is exhausted into a conduit 7 leading to the right-hand turbine, and is afterwards exhausted into a conduit 20. In a modification, the centre dynamo 18, Fig. 3, is of the induction type ; it is driven by the primary rotor of the first stage and the secondary rotor of the second stage, and develops about 50 per cent of the total output. The unit 19 is of the synchronous type, is driven by the secondary rotor of the first stage, and develops about 15 per cent of the total output. The unit 21 is of the induction type, is driven by the primary rotor of the second stage, and develops about 35 per cent of the total output. In this modification, the unit 19 may supply the exciting-current for the other units. In a modification adapted for direct-current generators, the centre unit is driven by two secondary rotors, and each of the three units develops approximately one-third of the total output. In a further modification, the centre generator is driven by the secondary rotor of the first stage and the primary rotor of the second stage. For units of the three - phase alternating - current type, each armature winding may be connected by three connexions 22, 23, 24, Fig. 6, to conductors 25, 26, 27. The field windings 28 are supplied from a suitable source of direct current. For direct-current units, each of the units 29, 30, 31, Fig. 7, is provided with armature taps 32, 120 degrees apart, which are connected by wires through slip-rings 33 with each other and form a three-phase electric gearing to maintain the proper speed relation.