Patent GB-378065-A (GB)
Title: Method of and apparatus for electrical control of electro magnetic interrupters
IPC: H01H51/34
Filed: 1931-04-29
Abstract: 378,065. Electromagnetic interrupters. SAFETY CAR HEATING & LIGHTING CO., 75, West Street, New York, U.S.A. April 29, 1931, No. 12680. Convention date, April 30, 1930. [Class 38 (v).] Timing devices.-In a control circuit for causing a delay in the rise of current in a circuit for achieving continuous cyclic actuation of an electromagnetic interrupter, which may control a flashing signal lamp, the controlling current which determines the length of a time period in the cyclic actuation is delayed in its rise by causing it to overcome the residual or remanent magnetism in a core of magnetic material with which a winding, separate from the interrupter windings, is associated and through which winding the current passes. As shown in Fig. 1 the controlled circuit consisting of the lamp &c. 10 and battery 11 is interrupted at spring contacts 12, 13 operated by a pivoted armature 16 under the control of an electromagnet with oppositely-wound windings 14, 15. The armature 16 also operates further spring contacts arranged in the circuit of a battery 24 to produce continuous reversals of magnetism in the core 26 of an inductance 25. A polarized relay 21 is arranged in the inductance circuit so that its armature 20 is attracted to engage contacts 22, 23 when the current in the inductance 25 has reached a maximum in one or other direction, the armature occupying a non- contacting position between these contacts with currents in the coil 21 below this value. In operation, from the position shown in which a remanent flux OF, Fig. 2, is present in the core 26 a current passes by way of contacts 27, 30 and 28, 31 through the inductance which current is retarded in its growth while the flux is reversed from the negative value OF to the positive maximum value BG the current thus rising to its maximum value OG and causing relay 19 to close contact at 22. This energizes the coil 14 to attract the armature 16, the coil 14 completing a maintaining circuit at contacts 28, 33. The circuit through the inductance is now broken the flux dropping to the positive value OC and the contact 22 of relay 19 is released. A reverse circuit through the inductance is now completed at contacts 28, 33, 45 and 27, 32 and a slow growth of current takes place during the reversal of the flux from the positive value OC to the negative maximum value JE after which the armature 20 engages contact 23 to complete the circuit of the opposing coil 15. This neutralizes the flux of the winding 14 and releases the armature 16. The energizing current of inductance 25 is thus broken, the relay 19 releases its contact 23 and the flux falls to the value OF. Thus a complete cycle of operations has been completed and a further cycle is initiated as already described, the time elapsing during the rise of current in the inductance 26 timing the opening and closure of the controlled circuit. If the opening and closing periods of this circuit are to be unequal the connections for forward and reverse currents through the inductance 26 are taken as shown to different tappings 37, 47 but if the periods are to be equal both connections are made to the same point. The time period of opening or closing may be varied by varying the positions of the tappings on the inductance to include a smaller or larger number of turns.