Patent GB-207549-A (GB)
Title: Improvements in and relating to automatic reclosing circuit breaker systems
IPC: H02H3/06
Filed: 1923-11-23
Abstract: 207,549. British Thomson - Houston Co., Ltd., (Assignees of Anderson, A. E.). Nov. 23, 1922, [Convention date]. Protective arrangements. -- Relates to automatic reclosing circuit-breaker systems, particularly of the kind wherein a breaker connects two sections, each of which may be independently energized. Should a fault occur in one section, the reclosing mechanism is so arranged that, when the load conditions of that section are such as to permit reclosure, the reclosing circuits are selectively energized from the section which is sound. The breaker is thus reclosed by the section having the higher voltage, and the voltage difference between the two sections operates a sensitive relay in the reclosing circuits. The arrangement is applicable to trolly systems having an earth or other return. Two conductors 1, 2 of a system are connected by a breaker 3, which is shunted by a resistor 23 and coil 10 and is held closed by a coil 4. A directional relay 7 controls a selective relay 8 and so determines that which of the sections 1, 2 is sound shall supply the reclosing circuits. The relay 7 effects this control by means of an operating and magnetizing coil 10, 16 respectively, the arrangement being such that sufficient current flowing from the section 2, in the event of a fault in section 1, will energize the coil 10 to move the contact 13 on its armature 9 to engage the fixed contact 14, whereas, if current flows from section 1 to 2, the said contacts will, assisted by a spring, be moved out of engagement, thus de-energizing the relay 8 and permitting section 1 to take the place of section 2 as the source of current for the reclosing circuits. A normally-closed hand-operated switch 22 is included in the reclosing circuit. The relay 35 which recloses the circuit of the coil 4, is constructionally the same as the relay 7. When the breaker 3 is closed the coil 4 is energized through the following circuit: from conductor 1 or 2, depending on whether the relay 8 is energized or not, conductor 20, contacts 24, 26 and coil 4 to earth. In the event of a fault, the overload relay 28 will open the contacts 26, deenergize the coil 4 and open the breaker 3. Current flows through the coil 10 of the relay 7 and, if the fault is in section 1, the contacts 13, 14, will close as described and energize the relay 8, which will open its contacts 19, 38 and close those 21, 39 so connecting the lead 20 with the sound conductor 2 and the operating winding 37 of the reclosing relay 35 with conductor 1. When the breaker 3 opens, it closes the contacts 30 and puts into circuit, through lead 20 and the sound conductor 2, the time relay 31, which, after a predetermined time, closes its contacts 33 and so places in circuit with lead 20 and conductor 2, the magnetizing winding 36 of the reclosing relay 35. When the resistance of the load between conductor 1 and earth has sufficiently increased and, consequently, also the voltage across the winding 37, connected thereto as described, the contacts 40, 41 will close and through them, a circuit will be established from the closed contacts 33 to those 26 and thence to coil 4, which will then reclose the main circuit, reclosing also the contacts 24 and establishing the original energizing circuit of the coil 4. Coils 31 and 16 are simultaneously de-energized. If a fault now occurs in conductor 2, with the contacts 13, 14 in engagement, and current is fed into conductor 1, the series of operations is similar except that contacts 13, 14 are separated by the current flowing from section 1 to section 2, as described, and the relay 8 is thereby deenergized. Consequently the coils 4, 31, 36 are connected to conductor 1, coil 37 to conductor 2, and the relay 35 operates in response to the load resistance between conductor 2 and earth. With this arrangement, coils 4, 31, 36 are always connected to the higher voltage section and coil 37 to the lowar voltage section, by means of the winding 10 of the relay 7 co-operating with the relay 8. The arrangement for reclosing the breaker in response to the load resistance is described in Specification 206,042. In the arrangement shown in Fig. 2, the contacts of the relay 8 are connected through tha switch 22 to tappings of the resistance 23 instead of directly to the conductors.