Patent GB-141653-A (GB)
Title: Improvements in or relating to energy-regulating arrangements for electric circuits
IPC: H02J3/30
Filed: 1918-07-15
Abstract: 141,653. Siemens - Schuckertwerke. June 13, 1917, [Convention date]. Alternating-current commutator and induction machines.-A buffer machine of the alternating- current. commutator shunt type, controlled by the automatic adjustment of its brushes, is employed for equalizing the load on a central source of supply. In the arrangement shown in Fig. 1, the commutator machine 7 is connected in cascade with a normal asynchronous polyphase machine 5, the rotors of the two machines being coupled together with a fly-wheel 6. The adjustment of the movable brushes 11 is effected through toothed gearing 12, 29 by a motor 13 fed from a small generator 14 excited by oppositely-connected windings 15, 16 controlled by a high-speed regulator 17, which is itself controlled by a transformer 18 in the central supply circuit. Under normal conditions, the windings 15, 16 neutralize each other, but on variation of the main or central current the regulator causes one or other of the windings to preponderate, thereby energizing the generator 14. The motor 13 then adjusts the brushes 11 in one direction or the other so that the buffer machine gives out or absorbs energy according to the conditions. To prevent over-regulation, a regulating resistance may be provided in the exciting system of the generator 14. The rate of adjustment of the brushes may be varied in different positions of the brush carrier by inserting in series with the exciting winding 20 of the motor 13 a regulating resistance 19 adjusted by the toothed wheel 12 of the brush carrier. In a modification, a variable speed ratio in the adjustment of the brushes is obtained by connecting the motor 13 to the brush carrier by means of elliptical gear wheels or by a crank and connecting-rod. In the arrangement shown in Fig. 3, the brushes are adjusted by a hydraulic motor comprising a pressure cylinder 27 with a piston-rod connected by gearing to the brush carrier. The piston-rod is actuated in one or the other direction by compressed oil under the control of the valve 32 connected to the balance lever 41 of an efficiency relay. When the load on the central supply varies, the left hand side of the lever 41 is raised or lowered and oil is admitted to one side or the other of the piston in the cylinder 27. The movement of the piston is transmitted to the brushes and also to the balance lever 41, so that the valve 32 is restored to its original position, thereby interrupting the regulating action in order to prevent over-regulation. During the regulating movement, the length of the rod system between the valve 32 and the end of the lever 41 is adjusted by means of a small constant-speed auxiliary motor 35 coupled by friction disks 36, 37 to a sleeve 38 into which is screwed the end of the rod 39 of the valve 32. In another modification, the adjustment of the brushes is effected by means of two oppositely-acting alternating-current motors mounted on the same shaft. These motors normally balance each other, but when the central current varies, one or other of the motors preponderates in order to effect the desired adjustment of the brushes. In the arrangement shown in Fig. 5, the adjustment of the brushes is controlled by the current in the consuming circuit 2 as well as by the current in the main supply circuit, an auxiliary motor 53 acting against a spring 54 being provided for this purpose. The shaft 78 for adjusting the brushes is actuated by the motor 13 and the auxiliary motor 53 through a differential gear 50. Both sets of brushes on the commutator may be adjusted simultaneously in opposite directions through a second differential gear 74, 75, 76. The planet wheel 74 of this gear is carried by a lever 73 frictionally attached to the shaft 78 and movable between stops, so that whenever the direction of rotation of the shaft changes, an immediate adjustment of the brushes takes place to compensate the change in the buffer machine from the motor to the generator status or vice versa. In a modification, Fig. 6, the auxiliary motor 53 is controlled by a relay having a coil 69 in the consuming circuit 2. The core 70 is suspended from a airing 57 and carries a rod 58 on which is mounted a contact 67. Two transverse rods 60, 61 carried by the rod 58 support a cylindrical weight 63, which is suspended between springs 62 and carries contacts 64, 65. When the current in the consuming device varies, the core 70 is adjusted and the contact 67 engages one or other of the contacts 64, 65 to cause the motor 53 to rotate in one or the other direction to adjust the brushes of the buffer machine. The weight 63 is furnished with wings 68 and placed in a damping fluid so that it can only follow the core 70 gradually under the action of the springs 62. After an interval, the circuit of the motor is interrupted and the motor comes to rest. Specification 24744/11. [Class 38 (iv), Electric supply and transmission systems &c.], is referred to.