Patent GB-868768-A (GB)
Title: Improvements in automatic signalling apparatus
Inventor: STONER CHARLES RICHARD PAUL
IPC: H04M11/00
Filed: 1958-09-02
Abstract: 868,768. Substation supervisory equipment. SOUND DIFFUSION (SALES) Ltd. Nov. 26, 1959 [Sept. 2, 1958; May 13, 1959], Nos. 28185/58 and 16473/59. Class 40 (4). Supervisory apparatus capable of transmitting its information over the national telephone network to a central control station, comprises a record medium upon which are impressed verbal or other signals descriptive of all the possible states of the apparatus to be supervised, sensing means for reproducing said signals and means for selecting for transmission those reproduced signals which are applicable at that time and for suppressing the others. The invention is described in relation to an electrical substation whose circuitbreakers require supervision. The sequence of recorded signals is as follows: (1) the exchange number of the control room to which the information is to be sent. This is recorded as a series of 8 kc. pulses with the correct on/off periods and correct interdigital pauses; (2) the identity of the substation in verbal form; (3) two 8 kc. bursts; (4) verbal announcement " circuit-breaker number 1 is open "; (5) an 8 kc. burst; (6) " circuit-breaker number 1 is closed "; and (7) similarly for all circuitbreakers in sequence; (8) an 8 kc. burst; (9) " that was a false message please ignore " (for use where loss of synchronism occurs); (10) an 8 kc. burst; (11) " send acknowledgement signal now " ; (12) an 8 kc. burst; (13) a delay period followed by " send repeat message signal now"; (14) an 8 kc. burst; (15) "transient start has failed" ; (16) a series of 8 kc. bursts. Apart from those used for dialling the control station the 8 kc. bursts are used for stepping a sequence switch. Signal amplifying and detecting arrangements, Figs. 2A, 2B (not shown).-The pick-up for the recordings is connected to a transistor amplifier whose output is fed via an 8 kc. band-pass filter to an amplifier detector circuit whose output operates a relay P (not shown). The amplifier output is also fed via an 8 kc. bandstop filter via a further transistor amplifier and a 3 kc. low-pass filter to lead b, Fig. 2C for outward transmission as required. With relays SP, TR and M all operated incoming signals may be fed over lead a to the input of the further transistor amplifier whose output is connected over a further make contact of TR to the input of the amplifier detector to operate relay P. Setting up of call to control station and normal operation.-Any change in the condition of a circuit-breaker operates a contact such as ax1 to produce a positive or negative pulse in transformer TSF1. This pulses, via a full-wave rectifier and transistor amplifier, the relay TS. Relay FS then comes up, followed by BC, RCO, PFS, MS, PR, relay PFS then releasing FS. Relay MS connects up the driving motor MTR for the reproducer. Relay PR closes the exchange loop to call the exchange. After a pause the dialling code commences P operating to each of the 8 kc. pulses received from the record to release PR to send the required digits to line. Relay T operates at the first pulse and D, RS and M follow the latter being operated over CS1. At the end of the dialling sequence T releases (it has a 5 second release period at this time) and operates CO which prevents FS from re-operating should TS be again pulsed. CO connects the stepping circuit for CS and releases RCO which enables the line output transformer TSF2. Relay M connects the reproducer amplifier to line over wire c. The record then announces " The position of circuit-breakers at .... substation is as follows :-". Then the two 8 kc. bursts operate P to step switch CS twice to position 3. If the first circuit-breaker is open - ve will be applied to wiper CS1 and relay M operates over MR6 to connect up the appropriate announcement. Otherwise it is suppressed. The next 8 kc. burst steps CS to position 4. If the circuitbreaker is closed +ve is applied to CS1 and M is operated over MR7 to connect up the appropriate announcement. Otherwise it is suppressed. Stepping in this manner continues until all the circuit-breakers have been tested. Then the switch will normally be stepped by 8 kc. bursts to position 45 in which M is again operated to send the message " Send acknowledgement signal now," after which another 8 kc. burst steps CS to position 46. When CS steps to this position SP comes up over wiper CS3 and TR then comes up over CS1, CS2. The amplifier detector is now set to be responsive to the incoming acknowledgement signal which is required to be a burst of tone between 2.5 and 5 seconds long. Relay P operates to the acknowledgement signal and if it is longer than 2.5 second T operates (its operate time is now 2.5 seconds because CO is operated). Relay NU follows. When T releases RS, M follows, DPO comes up, and PR and TR then release. PR releases the exchange line. SP releases after a 5 second delay and NU follows. Stepping is then continued by the 8 kc. pulses until position 50 is reached. When T operates on the last 8 kc. pulse (which is of 5 second duration) it releases BC and CS homes automatically to position 1 and the equipment restores to normal. Failure to receive acknowledgement signal.- This may be due to the fact that the control room has failed to give it, or that a signal received is too short (e.g. busy tone) or too long (e.g. N.U. tone). In the first two cases T is not up when SP releases and therefore TR releases. In the last case disconnection of the exchange line takes place as for a proper acknowledgement signal and the switch CS steps to the end of its cycle as before. However, NU is released by SP and so continues to hold RS. In the first two cases with the switch in position 46 and M still holding, the next message " Send repeat message signal " is sent and then CS is stepped to position 47. +ve over CS1 holds TR and M at this stage and any incoming signal is fed over lead a to the amplifier detector to operate P. This signal again must be between 2.5 and 5 seconds long. If no signal, or too short a signal, is received then the operation is the same as for no acknowledgement signal and RS stays up. The switch CS then steps to the end of the cyle. If the signal is too long then as in the case of the too long acknowledgement signal the switch CS goes to the end of its cycle, RM being operated but then released again in these circumstances. In the event of repeat message signal being of the correct duration T operates NU and RM operates over CS2 and locks. When the signal ceases T releases RS and brings up DPO, PR being held by RM so that the exchange loop is held. The switch CS then proceeds to the end of its cycle. Repetition in response to request.-In these circumstances with RM still up and holding PR when the final 5 second 8 kc. pulse of the cycle is finished relapse of T releases CO, D and DPO and re-operates BC which brings up MS to restart the motor MTR and also brings up RCO. The cycle then recommences as before with the exception that no dialling pulses are sent as RM is still holding PR. Reconnection when no acknowledgement or repeat message, signals are received.-When the switch CS reaches position 50, RS is up, enabling S to operate over CS1, CS2 and when CS goes to position 1, the first relay CA of a binary counting chain CA . . . CC operates. CA releases S and prevents PR from operating so that the exchange is not called. The equipment then goes through a whole cycle, so as to allow time for the control station to clear if it had been busy when the first attempt to call it had failed. At the end of this cycle CB of the counting chain is operated. This releases CA and S. With RS still up and PR no longer disabled a second call is put through to the control room. If this is also unsuccessful after a further blank cycle a further call is attempted, and so on until after 4 unsuccessful calls with CA, CB and CC all operated the full count relay FC is operated. This releases RS so that no further cycle can be commenced and the equipment is normalized. Incoming calls.-Incoming ringing current operates RX followed by RR, BC, MS and FR. Relay RR breaks circuit for the dialling relay PR, but otherwise the usual cycle is commenced and when T releases at the end of the dialling period PR is brought up to close the exchange loop and trip the ringing and the cycle of announcements is carried out. If a person at the substation wishes to answer an incoming call personally, he operates the button KTC which brings up TC. This disconnects PR and hence disconnects the equipment from the line. If a cycle is already in progress when the incoming call is made the caller will hear the remainder of the cycle unless button KTC is pushed as previously described. Irregular operation.-Arrangements are provided to indicate if the switch CS loses synchronism with the record. The 8 kc. bursts for stepping the switch may be either of 50 msec. or 150 msec. duration. The contacts of bank CS3 are connected either to relay HS or to contact so2 according as 150 msec. or 50 msec. pulses are expected at that position of the switch CS. Slow-to-operate relay SO will operate only to 150 msec. pulses. If a 50 msec. pulse is received when 150 msec. is expected HS operates and locks because so3 fails to open. When P falls back SL is brought up. If a 150 msec. pulse is received when a 50 msec. pulse is expected SL operates over the operated so2 contact. Thus SL operates when synchronism is lost. Relay SL locks and holds M operated for the rest of the cycle. Thus both announcements for each circuit-breaker are thenceforward transmitted to line. Furthermore, when CS reaches position 43, since M is still operated in this position the message " That was a false message, please ignore " is sent. Transient start during cycle.-If during a cycle a further change occurs in the circuitbreaker position, TS brings up FS which locks. At the end of the cycle with FS still up a further call is init