Patent GB-190828186-A (GB)
Title: Improvements in or relating to Electric Alternating Current Distributing Systems.
Inventor: MERZ CHARLES HESTERMAN
Filed: 1908-12-24
Granted: 1909-12-23
Abstract: 28,186. Merz, C. H., and Price, B. Dec. 24. Distributing; switches. - The windings which normally produce balanced forces on a relay, or upon a transformer connected to a relay, are taken directly or through transformers from adjacent points in a multiple-wire system of distribution. In the arrangement shown in Fig. 1, the cores a, b, c are surrounded by a laminated ring e, which is provided with a winding f connected to the winding of the electro-magnet. If the cable be lead-covered, armoured, or sheathed with a conducting cover g the covering, armouring, or sheathing is interrupted as at the point h, and an insulating covering j substituted, the covering being earthed. As shown in Fig. 2, the three cores a, b, c are connected to windings a', b<1>, c<1> upon a magnetic core e<1>. When the balance is disturbed, the secondary winding f energizes the winding of the magnet a<2>. Instead of the windings a', b<1>, c<1> being connected directly to the cores a, b, c, they may be connected to the secondaries of current transformers, the primaries of which are placed in the respective cores. To protect the circuit in the case of an overload, a time-limit fuse may be placed in each of the secondary circuits of the transformers together with a measuring-instrument. In the arrangement shown in Fig. 4, the secondary windings m of the current transformers are connected in series ; or they may be connected in parallel, in which case measuring-instruments and fuses may be employed. In the arrangement shown in Fig. 6, the secondaries m of the current transformers are each connected to a solenoid n, the plungers o of which are connected to a flexibly suspended frame p, which is controlled by a three-armed spring r, mounted upon a support s. The support s also carries contacts engaging with contacts p<1> upon the spring r, when the balance is disturbed, to complete the circuit of the relay or tapping-coil a<2>. The solenoids n may be connected directly to the cores a, b, c. In a modification shown in Fig. 8, the windings t of the magnetic cores u are connected directly or through transformers. Rotatable disks of copper v or the like are mounted in the gaps of the cores u. The spindles v<1> of the disks v carry pulleys w connected by flexible connexion to one end of a spring support y, which passes through a hole z<1> in a conducting plate z. When the balance is disturbed, due to a leakage or overload, the support y engages with the plate z, thereby completing the circuit of the winding of the magnet a'. A further modification is shown in Fig. 10, in which the trip coil is provided with three windings 1,2,3, each connected in series with a corresponding solenoid n connected directly or through a current transformer to the cores a, b, c. Each solenoid n is connected to one of the extremities of a Y-shaped lever p, each arm of which is adapted to close a switch 4 which shortcircuits one of the windings upon the core of the tripping-device. , In a modification of the arrangement shown in Fig. 10, only one winding is placed upon the tripping-device, which is normally shortcircuited. When a fault occurs, the winding is energized by the action of the solenoids upon the Y-shaped lever.