Patent GB-465356-A (GB)
Title: Improvements in or relating to electric remote indicating systems
IPC: H02J13/00
Filed: 1935-11-05
Abstract: 465,356. Electric signalling systems. GUNNING, P. F. Nov. 5, 1935, No. 30608. [Class 40 (i)] [Also in Group XXXIX] Electric power substations are supervized over the public exchange network. To ascertain the condition of equipment at a sub-station, a call thereto is set up automatically or manually and after a delay to provide for normal reply if the sub-station is attended, tone signals are sent in code from the substation, indicative of the substation and of the condition of circuitbreakers, meter readings &c. A change in the condition of equipment at the sub-station automatically makes a distinctive call to any exchange operator who extends the call to the supervising station which then receives the tone signals, or the call may be extended automatically to the supervising station. Variation of tone frequency or duration may be used to give quantitative indications. Call to sub-station.-Ringing current operates relay ST shunted by a rectifier and connected in parallel with bell BL, relays A and B follow and back stroke magnet SM is energized whereupon A and B interact with SM to step switch S idly to its last contacts to provide time for a normal reply. If this does not occur magnet DM operates in parallel with SM in the last position of S to move D one step whereupon SS pulls up over D3, loops the line to trip ringing and prepares the circuit of tone generating relay TR. Relay ST falls back but S continues to step. Certain contacts of S3 are connected to battery over contacts controlled by circuit breakers OCB1-3, the corresponding contacts of S4 are connected direct to battery as are also certain initial contacts according to a code identifying the sub-station. If a circuitbreaker is closed, battery is connected over wiper S3 during the time the wiper engages the contact whereas battery connections over S4 exist only during the shorter time when A is operated. The battery connections operate relay P which connects up vibrating tone relay TR for transmitting signals over the line so that with the contact breakers in the position shown, the complete signal comprises 3 dots (identifying the substation) followed by dash, dot, dash for the contact breakers. Relay TR is preferably energized by a local battery and not from the power supply. By connecting two adjacent contacts of S3 to each circuit breaker, and using a bridging wiper, the dashes may be made longer. Each time S reaches its last contacts, DM takes a further step and the signal is repeated. After any desired number of repetitions, the operating circuit over D1 for relay A when S is normal is opened, and D homes over further commoning of D1, relay SS falling back to open the loop. If the call is answered before S reaches its last contacts, CO which is unaffected by ringing current pulls up and operates P to prevent the stepping of DM. When S reaches its first contacts it stops since, owing to the relapse of ST and the non-stepping of D, there is no fresh circuit for A. Circuit breaker initiates call from sub-station. -When a change over occurs, relay OCB is released during the transit time of the circuit breaker, opens its own operating circuit and operates A over D2 and S1. Switch S steps as before but each time A operates, SS pulls up and loops the line to flash the calling lamp at the exchange (manual). The operator recognizes this as requiring a call to the power control station which, when connected to the substation, receives the code and supervisory signals in the manner described above. In the case of an automatic exchange system, the change over of a circuit breaker would be arranged to cause the transmission of digit 0 to call an operator or of the digits of the power control station.