| 摘要 |
381,510. Protective cut-out systems. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Fitzgerald, A. S. ; Warwick Road, Wynnewood, Pennsylvania, U.S.A.) May 12, 1932, No. 13732. Convention date, May 12, 1931. Addition to 274,070, [Class 38 (v), Electric switches &c.]. [Class 38 (v).] Relates to protection against faults within a line section by means of a comparison of high-frequency currents superposed on the line as in the parent Specification. A transmitter 19, 20 is located at one end of the section to transmit only during alternate half-cycles of the circuit current at this end. A receiver 21 at the other end is so connected as to receive only during alternate cycles of the circuit current at its own end. The arrangement is duplicated, as shown, so that unless there is relative reversal of circuit current between the two ends due to fault, the receiver at one end is receptive to the high-frequency oscillations at the other end and the circuit-breaker will be locked closed to prevent operation with through faults. According to the invention, the protective relays 33 which completes the tripping circuit of the circuit-breakers 13 are arranged to be operated by overcurrent in the coil 35 (connected with the current transformer 23 in the line) and are restrained when the line is sound by a winding 36 which is controlled by a receiver relay 27 itself controlled by its local receiver 21. The transmitters and receiver are put in action on fault by a starting relay 30 which may be of the overcurrent type. This relay short-circuits one of the windings 38 of the receiver relay and the other winding 22, connected with the receiver maintains the relay closed and the restraining winding 36 energized as long as both transmitters transmit alternately. If, however, the fault is in the section itself the transmitters will transmit simultaneously so that the receivers cannot receive ; the relay winding 38 is deenergized and the relay 27 opens thereby open-' ing the circuit of the restraining winding, permitting closure of the relays 33 and tripping of the circuit-breakers. In a modification, the receiver relay is of the double-throw type and when de-energized is adapted to complete a circuit through the contacts 32 to trip the circuit-breaker and when energized to complete through its second contact a circuit through the restraining winding. |
