GB117546A - Improvements in Electric Time Relays. - Google Patents

Abstract

117,546. Engelhard, A., and Soc. Automatisme et Appareillage. Oct. 19, 1917. Electro-magnetic switches; electrically-released switches; protective arrangements.-Time element relays for closing the circuit of instantaneously-operating cut-outs enabling the cut-outs in the different parts of a 'distributing system to be graded in respect of their time element so that the cut-out of the line immediately in front of the part where the disturbance occurs alone is operated consist of a contact-bridging member 4 supported by a cord passing over a pulley 2 so that, on abnormal conditions arising, time is consumed by the bridging member in falling before it reaches the contacts 15 slidably adjustable on the rod 14. The shaft 1 which carries the fixed pulley 2 drives, through speed-reducing gear, a second shaft 5 carrying a fixed pulley 7 in a groove of which a cord 8 is fixed carrying at its lower end the core 9 of a solenoid 12. The solenoid is normally energized from a local source II through a relay having a solenoid 16 and normally closed by the spring 17 against the action of the current in the solenoid 16 which is proportional to the current in the system. With excess currents in the system, the solenoid 16 breaks the local circuit and the resultant de-energization of the solenoid 12 allows the weight of the bridging-member 4 to overbalance the weight of the core 9, the bridging-member slowly falling retarded by an adjustable braking-device or by inertia bcdies such as the cylinder 13. The time element may be varied by varying the weight of the bridging- member, the adjustment of the braking-device and the position of the sliding contacts 15, The pulleys may be mounted on the same shaft if pulleys of correct relative size are chosen. The relav is self-resetting, the core 9 being pulled down by the solenoid 12 when the overload ceases. To deal with the heaviest overloads such as those due to short-circuits, the time element is eliminated by the use of secondary contacts similar to 15 and in parallel therewith located immediately below the bridging-member 4 in its raised position and adapted to be brought into the path of the bridging-member against the action of a spring by means of electro-magnets in series with the relay winding 16 on the occurrence of heavy overloads.