Patent GB-339643-A (GB)
Title: Remote indications and supervisory control systems
IPC: H02J13/00
Filed: 1929-08-12
Abstract: 339,643. Standard Telephones & Cables, Ltd., and Chapman, S. Aug. 12, 1929. Selective signalling systems.-In a system for signalling circuit breaker positions, meter readings, tap change switch positions and for telephoning over a two-wire circuit or its equivalent, an individual code of voice frequency impulses is transmitted over the circuit for each indication, the code being made by suppressing certain of the impulses produced by the movement of a normally stationary distributor. If two or more signals originate together the transmission is effected in a predetermined sequence. Circuit breaker and tap change switch indications. The substation apparatus is indicated in Fig. 1. When a circuit breaker changes its position one of the switches SW, e.g. SW5, changes over and the relative S or T relay, T5, energizes in series with relav E, from DS1 and locks to a make contact of T5. The polarized relay P5 changes over to prepare to signal the next change. Relay E completes a circuit for J which operates completing circuits for the valves in the oscillator OS. When the filaments are emitting fully. M energizes followed by G1 starting the distributor motor MC. The distributor wiper moves over the contact bank and relay I energizes when the first terminal connected to positive is reached and releases on the disconnected terminals. Certain of the contacts are connected via distributing frames TS1, TS2 to the contacts of the T and S relays and the energized relay earths some of these leads enabling the relay I to transmit to the main station a 3 figure code of which the first digit is either 1 or 2 impulses and the total number of impulses does not exceed 22. A register, Fig. 3, at the main station receives the impulse trains and sets indicators, Fig. 4, to indicate the change made. When the last impulse of the 3rd digit has been transmitted relay Z pulls up, and holds up until the distributor has returned to normal, keeping relay I energized to prevent the transmission of further pulses. As the distributor reaches its home position springs DS1 open, releasing E and the operated T or S relay, leaving the circuit ready to transmit another indication. If a tap change switch changes its position one of the circuits TTC1-TTC4, of which a set of 4 is provided for each tap change switch, is affected. The leads LT1-LT4 are connected to the similarly marked conductors indicated in Fig. 2. When the tap change switch moves the arm indicated to the left of Fig. 2 steps on to its next contact and the relays A-D, X-W alter the condition of one set of the leads LT1-LT4. One of the relays U1-U4 or V1-V4 is thus energized in series with E and the system operates in the same manner as described for a circuit breaker change, the operated relay controlling the transmission of a code peculiar to the relay energized. Transmission of meter readings. When a meter reading is required the key MK2, Fig. 2, at the main station is moved to the left energizing P2 and R3. J2 energizes connecting the valve filament circuits and when the valves are emitting fully, T2 energizes allowing T3 to pull up. During the slow release period of R3 relay I is energized connecting the oscillator to the line and a long voice frequency pulse is transmitted to the sub-station. Relay VF responds to the pulse releasing A and energizing B and N. Relay H energizes followed by J which prepares the oscillator OS as before and the distributor motor commences to rotate. Relay H also completes an energizing circuit for W and this relay in turn completes circuits for relay K and magnet X. The meter scale is divided into 50 sections, each section being associated with one of the contacts MK in a group WM1-WM5 and magnet X pulls down the wattmeter pointer to make contact with one of the sections, thus making one of the contacts MK. As W and K are both energized the relative F relay pulls up and relay G energizes. The relay F in combination with the operated contact M marks contacts in the bank of DC resulting in the transmission to the main office of a code peculiar to the MK contact made. When the wattmeter reading has been sent DC returns to its home position and contacts DS1 open, releasing F and G. When G energized at the beginning of the transmission L11 made its "fly" contact and this relay operates completely when G releases, preparing a circuit for L22. Relay R changes over on the release of G energizing WL, and magnet Y pulls up. Magnet Y is connected with a wattless meter and makes a contact MKL exactly as X enabled a contact MK to close. Relay FL energizes and a code representing the wattless meter reading is transmitted to the main station. When the code is completed, G releases energizing L22, and H falls away, releasing the equipment. Main station apparatus. The code signals operate relay VF2 which repeats the digits in turn to the relay groups A, Band C, the relays X2, Y2, Z2 changing over from one group to the next as each train terminates. When the transmission is completed one A relay, one B relay and one C relay is energized. The A relay energizes a D relay, the B relay an S relay in the group selected by the energized D relay, and the C relay extends a marking potential over the contacts of the energized S relay to mark one of the wires incoming to the indicating apparatus, a selection of which is illustrated by Fig. 4. If a circuit breaker indication has been transmitted one of the wires connecting to an apparatus such as SRC. is marked. The relay P3 changes over, lighting either the red lamp RL or the green lamp GL. Relay H3 pulls up and locks to the release, key RK lighting the pilot lamp PL, ring- ing the alarm bell BE1 and maintaining the circuit for the glowing lamp after the marking potential is removed. If a tap change switch indication is received one of the relays P5-P8 in TTR is changed over and the corresponding holding relay H5-H8 energized. The relative position lamp is lit and the H relay maintains the glow until the key RK is operated, the pilot lamp being lit and the alarm bell run as before. If a meter reading is received one of the conductors to MRC is connected to positive potential and the meter MM moves to a position corresponding to the current flow through the resistance R giving an indication of the position of the meter at the substation. Telephone arrangements. To call the main station from the sub-office a two-position key (not shown) is moved, energizing a relay similar to the S or T relay, and one of two codes is sent depending on whether the key is moved into its first or second position. One of the wires leading to P4, Fig. 4, is energized, P4 changes over, energizing TB which locks and rings bell BE2 and Q4 changes over. When the receiver is lifted, springs TA open and TB releases. When next a call is required, the key is moved to its other position, and the second code is transmitted marking the other wire to P4. To call the sub-office the key MK2 is moved to the right. The oscillator starts up as before and I is energized, but its circuit is intermittently connected to negative via contacts of relay R2 which interacts with relay S2. A train of impulses is thus connected to line resulting in relay A releasing as before but relay N (which is slow acting) does not pull up and U energizes, ringing bell BE and locking to the springs SBE. When the sub-office attendant replies, springs SBE open and C releases. Precedence of certain calls. The relays U and V are made slower acting than relays Sand T so that if both a tap change switch and a circuit breaker change together, the circuit breaker indication is always transmitted first. Both circuit breaker and tap change switch indications have precedence over meter readings, for should a meter reading indication have been demanded when a circuit breaker or tap change switch changes, the operation of relay E releases the operated F or FL relay and allows the position change indication to proceed. If the meter reading relay H has energized it remains locked to contacts of L22 and the meter reading is transmitted after the position change signal has been sent. Telephone calls may be given any desired priority by making the marking relays more or less slowly operating than the S, T, U or V relay.