Patent GB-428652-A (GB)
Title: Improvements in electric supply systems
IPC: H01H50/72
Filed: 1934-06-27
Abstract: 428,652. Supply systems; electromagnetic switches. TRIGGS, W. W., 57, Lincoln's Inn Fields, London.-(Adiake Co. ; 319, West Ontario Street, Chicago, U.S.A.) June 27, 1934, No. 18978. [Class 38 (iv)] [See also Group XXXVII] Substituting sources in service.-An emergency supply arrangement, particularly for railway signalling systems, comprises a main source of supply, 24, an auxiliary source of supply 25 and a common load 20 the connection of each source to the load being controlled by a slow-acting relay D or C and a quick acting relay A or B the former operating to prevent simultaneous connection of both sources to the load during a transfer, the energization of the relays being controlled in response to the voltage of the main supply source. The coils of the relays A, B, C, D, may be connected in series and through a contact of a relay E to the primary or secondary side of the main supply transformer, if the main source provides A.C., the coil of the relay E being connected to be responsive to the voltage of the main source and the arrangement being such that, with the relays E, A, B, C, D, energized, the contacts of A and D are closed and those of B and C are open so that the load is supplied from the mains 24. Alternatively windings A, B, C and D connected in series with each other, may be in parallel with the coil of relay E and the contact of relay E may be in series with the contacts of relay A. In a modification the coils of relays A, B, C and D may be on one core controlling four contacts in the manner described, contacts C and D being slow-acting. The relays may be of ordinary construction or may be of the type in which a glass tube, such as 51, containing an inert gas and two contact electrodes such as 62, 63 is partly filled with mercury and contains also a hollow open ended cylindrical armature e.g. 59, 66 which is pulled down into the mercury by gravity or magnetic action to raise the level of the mercury so as to connect the contact electrodes or is raised up out of the mercury by buoyancy or by magnetic action to lower the level of the mercury and break the connection between the contact electrodes. In this type of relay, time delay is obtained by making one end of the cylindrical armature conical as at 61 and providing a restricted opening 60. All the relays may be of this type and the relays A, B, C, D may have their external sleeve polepieces 49 arranged to form the air gaps in the four outer legs of a core construction 26 having a common middle leg surrounded by an energizing coil 27 the armatures 66, 67 of the relays A and D being pulled down by magnetic action to close their contacts and those 58, 59 of relays B and C being lifted to open their circuits when the core is energized. Springs 33 and 34 are provided in the glass tubes to prevent damage thereof. In a unitary structure comprising the switches A, B, C and D the magnetic circuit of each switch consists of two laminated L-shaped pieces bolted together to form a vertical limb and two horizontal pieces to which the magnetic sleeve-like poles on the switch tubes are secured by means of clamping rings. The vertical limbs of each relay magnet are assembled together so that the horizontal limbs thereof extend outwardly in the form of a cross, and the energizing coil is arranged to surround the vertical limbs.