| 摘要 |
353,732. Protective cut-out arrangements. ASSOCIATED ELECTRICAL INDUSTRIES, Ltd., Bush House, Aldwych, London.-(Assignees of Crichton, L. N.; 61, South Munn Avenue, East Orange, New Jersey, U.S.A.) Aug. 22, 1930, No. 25168. Convention date, Aug. 26, 1929. [Class 38 (v).] To prevent tripping of a circuit-breaker 31 owing to the unidirectional current component superposed on the steady fault current when an asymmetric fault occurs in a line 29 supplying a load 30, which may be a traction system, the current actuating winding 34 of an impedance relay 33, such as described in Specification 103,947, [Class 38 (v), Electric switches &c.], is shunted by an arrangement of resistance 40 and reactance 41 preferably approximating in value to those of the line 29. The shunt byepasses the unidirectional component, leaving the steady fault current to actuate the relay 33, which is therefore responsive to the true impedance and does not operate with an apparently low impedance due to a fault, say, in a neighbouring section. The voltage coil 36 of the relay is fed from a transformer 37, but the invention is stated to be applicable also to overcurrent relays. |
