GB378574A - Improved means for protecting electric lines with impedance relays - Google Patents

Abstract

378,574. Protective cut-out arrangements, induction relays. SIEMENSSCHUCKERTWERKE AKT.-GES., Siemensstadt, Berlin. June 4, 1931, No. 16305. Convention date, June 5, 1930. [Class 38 (v).] In the protection of electric lines by means of distant relays which operate in a time dependent on the resistance or reactance of the line between the relay and the fault, the induction disc 7 which under the influence of current and voltage coils 6, 8 takes up a position dependent on the resistance is provided with an adjustable stop which limits the furthermost position of the disc so that the greatest time of action is limited and adjustable. When, in the arrangement shown, the current in the driving magnet 8 drops below a certain value and at the same time the voltage remains sufficiently high the armatures 17, 18 complete a local circuit to energize a coil 15 and release a clockwork driven contact-arm 11. The time taken by this contact-arm to engage with the cooperating contact 10 on the disc 7 and trip the circuit-breaker 2 depends upon the position assumed by the contact 10 in accordance with the resistance &c. of the line. Even for a very high resistance, however, the time is limited by the adjustable stop 19 which determines the most distant position of the contact 10, and the time is constant for all values of resistance &c. above a critical value. The shortest time of operation may be varied by adjusting the initial position of the arm 11. The constant maximum time may be graded from one relay to another along the line. With lines fed from both ends additional relays with counterrunning time graduation may be used.