GB285870A - Improvements in the automatic protection and control of electrical installations - Google Patents

Abstract

285,870. Schild, S. Feb. 24, 1927, [Convention date]. Cut-out arrangements.-Electrical systems, for example, the incoming lines L1, L2, the power transformers A, B, C and the outgoing lines L3, L4 are protected against fault by means of a maximum and minimum relay N which through switching mechanism K isolates all parts of the system on fault, and then reconnects them in sequence, and switches off the defective parts by means of a maximum current relay M. Upon removal of the fault, the defective parts are switched in again automatically. The switches which isolate the various parts of the system A, B, C, and A2, B2, C2, for example, are of the double coil type one coil when energized serving to close the switch and the other to open it. The energization of these coils from the battery D is under hand control by the selector W which determines which of the main switches shall come under the automatic control of the cutting-out and resetting controller K which is driven by the motor G when the voltage relay in one of the incoming lines assumes one of its closed positions due to increase or decrease of voltage. When, for example, the line L1 becomes live the contacts a, b of the relay N close and the motor G commences to rotate the drum. The connections of the drum controller to the main switches are such that the main switches in the system are closed in sequence. During this switching-in action, if a fault occurs in the next succeeding section (for example, between the switches A1 and A2) then the maximum relay M will operate and the main switch just closed will be opened again. In position 11 of the controller, it is stopped as the supply is automatically cut off from the motor G. If the voltage on the conductor L1 fails, for any reason, the motor is restarted and all the switches are switched off at position 13 of the drum. In position 14 the motor is again stopped and only on reappearance of voltage on line L1 is the switch mechanism again set in operation by the voltage relay N.