Patent GB-553433-A (GB)
Title: Improvements in or relating to supervision of electric power supplies
IPC: G08C19/16
Filed: 1941-08-17
Abstract: 553,433. Electric signalling systems. STANDARD TELEPHONES & CABLES, Ltd., McWHIRTER, E. M. S., and CHAMBERS, C. H. Aug. 17, 1941, No. 9040. [Class 40. (i)] In a telemetering system, a cumulative meter such as a watt-hour meter controls two registers alternately during successive time periods and each register when dissociated from the meter effects the transmission of signals in accordance with its setting. The line can thus be employed also for the transmission of other meter readings or for other purposes. As shown, the registers comprise pairs of step-by-step switches RA,RB and RC,RD which record the impulses received from the meter in eights and units. The apparatus normally operates under the control of a time switch T which has a cycle of 4 minutes, but for fast impulsing, as explained below, an alternative time switch TT having a cycle of ¢ minute comes into service. After the register RA,RB has been recording for 2 minutes, relay CO changes over and substitutes the register RC,RD, and after a further 12 seconds the switch RST moves off-normal and connects up relay ST to start sending. The sender becomes associated over a finder and transmits first a series of impulses identifying the meter and then two series of impulses in accordance with the positions of the switches RB, RA, which are made effective in turn by RST. If in any 2 minute period the setting of one register is the same as that of the other register during the preceding period, sending is suppressed by means of relay NS. To effect the comparison, two additional switches RAC, RCC retain the settings of RA, RC respectively after the latter restore in readiness for fresh recording and act in conjunction with RB, RD which do not restore until the beginning of their recording periods. The change from a 4 minute cycle to a ¢ minute cycle is controlled by relay AA which is adjustably biassed through a rheostat. At each impulse from the meter relay AT releases AB which operates AA and makes a charging circuit for condenser QA, the charge being dissipated when AT relapses through resistance YM and AA. Any charge remaining when AT reoperates at the next impulse goes directly through AA which, if the charge is sufficient, operates to hold AB and connect up AL. The switch RST if off-normal restores, and an alarm code 73 is sent, after which relay ALR energizes and changes over relay TD to substitute the time switch TT for the switch T. The apparatus continues to operate on a ¢ minute cycle until the impulsing rate decreases sufficiently to allow AB to release, and then relay AF energizes, reoperating AL and releasing ALR, with the result that a code 74 is sent and the time switch T is brought into use again. Separate meters for import and export are provided and the registers are arranged to be connected to whichever meter predominates. For this purpose, condensers QB, QC are progressively charged by the impulses from the two meters, and at a certain point in the time cycle when relays M, MR are up the difference of the charges is applied across resistance YL. Achange from import to export ionizes a cold cathode tube and operates relay DA which connects up relay S to send a code 71 and to change over relay DD, transferring the registers to the export meter. Relay DR also changes over so that a return, to import will cause the operation of DB, the code in this case being 72.