Patent GB-101151-A (GB)
IPC: H02H7/26
Filed: 1916-08-07
Abstract: 101,151. Cole, W. H. Aug. 12, 1915, [Convention date]. Protective arrangements; electro-magnetic switches.-In a system of electric distribution, wherein parallel conductors or feeders are connected to cut-out devices, which act when the ratio between the currents carried by the feeders exceeds a certain value due to a fault, the cut-out devices disconnect the faulty feeder when the disturbance is due to an increase, decrease or reversal of current therein. As shown in Fig. 1, two parallel feeders 3, 4, connected to the mains 1, 2 at two distributing- stations, have at each end switches 5 adapted to be opened by electro-magnets 6 when the local battery circuits 7 are closed at the contacts 9. An electro-magnet 10 has two windings 12, 13 connected to the secondaries 17, 20 of transformers, the primaries 18, 21 being in the feeders 3, 4. A pivoted armature 11 also has two windings 14, 15 in series with the windings 12, 13. One of each pair of windings predominates over the other, so that, under normal conditions, the armature is held against the stop 24. When the ratio between the currents becomes excessive, the windings are arranged to cause a change in the polarity of the system, and the contacts 9 are closed by movement of the armature 11. In a modification, the armature has one winding only connected to one transformer and the electro-magnet one connected to the other transformer; each winding has in series one of two opposing coils surrounding a core connected to the armature. When a disturbance takes place, one of the coils predominates, attracts the core, and closes the local circuit contacts by tilting the armature. In a modification of this second arrangement, the coils and core are replaced by windings on a transformer core. These windings tend to produce opposing currents in each other, so that if one is greatly in excess of the other, the latter receives an induced current, which alters the polarity of either the electro-magnet 10 or armature 11 and causes displacement. In another arrangement, a double core 32, 33, Fig. 2, carries the arm for closing the contact and is acted on by two pairs of windings, one pair 35, 38 augmenting each other, and the other pair 36, 39 opposing each other. One winding of each pair is connected to one transformer, the other winding to the other transformer. In a modification of this arrangement, each pair of windings is replaced by one winding, the connexions being arranged so that the currents produced in the transformer secondaries are added in one winding and opposed in the other. As applied to three or more feeders a, b, c, &c., Fig. 7, each local circuit including an electro-magnet 6 has two sets of contacts, one set 90 controlled by, say, the sensitive device B, and the other set 91 by the device C. As shown, each of the devices B, C is constructed as in the form shown in Fig. 1. Assuming a fault &c. occurs in the feeder b, both devices B, C will be effected, owing to the disturbance in the current ratio, and the switch 5 in the feeder b will be opened. Specification 7457/15 is referred to. The Specification as open to inspection under Sect. 91 (3) (a) states also that the cut-out devices will act on phase difference of a definite ratio. This subject-matter does not appear in the Specification as accepted.