252,230. Automatic Telephone Manufacturing Co., Ltd., and Hudd, A. E. Feb. 13, 1925. Distant control systems; tell-tale apparatus.- In a system for controlling and supervising from a remote point the operation of a number of apparatus units, such as circuit breakers, at a substation, the apparatus units are selected by a constant number of impulses which are transmitted under the control of a step-by-step switch at the control station. The selection of any particular unit is determined by the position in the impulse train of an impulse of distinctive character and is checked at the control station prior to the operation of the selected unit. The apparatus at the control station, Figs. 1 and 2, comprises a number of keys K1, K2, K3, one for each unit and adapted to be operated upward. ly or downwardly according to whether the circuit breaker is to be closed or opened, a common control key OK for effecting the desired operation, a rotary switch RLS1 which during rotation controls the transmission of the impulses and at a particular contact selected by an operated key the transmission of a selecting impulse, of distinctive character, e.g. an impulse of negative polarity. The impulses are transmitted over lines 17A, 18A which lead to the substation apparatus, Figs. 3 and 4. At the substation, rotary switches RLS2, RLS3, RLS4 are operated in the following manner by the transmitted impulses; the switches RLS2, RLS3 are stepped forward synchronously with the control station switch until the marked contact of the latter is reached, when the selecting impulse causes the transference of the impulsing circuit from the switch RLS3 to the switch RLS4. The switches RLS1, RLS2, RLS4 are then stepped forward by impulses of normal polarity until the switches RLS1, RLS2 occupy their normal position. Thus after the transmission of the trains of impulses, the switch RLS2 at the substation again occupies its normal position and the switches RLS3, RLS4 occupy positions which are complementary to each other. A circuit is closed by the switches RLS3, RLS4 for operating a lamp L1 associated with the operated key to provide a check on the selecting operation. An operating circuit, e.g. the circuit 42, 43, Fig. 4, for opening or closing the selected circuit breaker may then be closed by the key OK, Fig. 1. When a circuit breaker is closed or opened the operation of rotary switches RLS5, RLS6, Figs. 2 and 3, at the substation and control station is initiated and impulses are transmitted over the same line wires. The circuit breakers are associated with the third, fifth, seventh, &c. contacts respectively of the bank of contacts associated with the wiper W5A of the switch RLS5 so that two impulses are transmitted over the lines for each breaker. The first impulses for all the breakers are always of the same polarity, but the second impulses are of the same or opposite polarity, depending upon the position of the circuit breakers. Sets of supervisory lamps such as RL2, GL2 are provided for the breakers, each set being controlled by two relays. One of these relays is operated by the first impulse to control the locking circuit of the second relay which is energized or left deenergized according to the position of the breakers. The wipers of the step-by-step switches at each station are moved in a continuously forward direction in a single plane. Selection of circuit breaker. Assuming that it is desired to select the circuit 42, 43, Fig. 4, for closing the circuit breaker associated with the key K1, the latter is operated upwardly to connect battery to the corresponding contact in the path of wiper W1A and operate a slow-acting relay SR3 which energizes the stepping magnet M1. The relav SR3 transmits an impulse over the lines 17A, 18A to energize a relay QR3, Fig. 4, which is parallel with a polarized relay PR1 at the substation. The relay PR1 is not energized in view of the polarity of the impulse, but one relay QR3 operates the stepping magnets M2, M3 of the switches RLS2, RLS3. When the magnet M1 is energized, it opens the contact 23 and thereby de-energizes the relay SR3 which opens the circuit of the magnet M1. The wipers W1A, W1B, W1C are stepped forward one step upon de-energization of the magnet M1 and the relay SR3 retracts its armature to open the line circuit and allow each switch RLS2, RLS3 to move a step. When the wiper W1A of the switch RLS1 reaches the contact marked by the key K1, a circuit is completed for the relay QR2 which reverses the battery connections to the lines 17A, 18A. This impulse energizes both relays QR3, PR1 at the substation. The relay QR3 operates the switch RLS2 through a further step but the relay PR1 energizes a relay COR1 which transfers the impulsing circuit from the stepping magnet M3 to the magnet M4 of the switch RLS4. Meanwhile the wiper W1C of the switch RLS1 energizes the relay SR3 which operates the magnet M1 and thus moves the wipers of the switch RLS1 into the second position. In this position the relay QR2 is deenergized and the battery connection to the lines 17A. 18A is restored to its original condition. Impulses of the same polarity are then transmitted under the control of the relay SR3 and the switches RLS1, RLS2. RLS4 are stepped forward until the switches RLS2, RLS1 reach their normal positions, say after the transmission of 25 impulses. Under these circumstances the switch RLS3 occupies its 1st position and the switch RLS4 occupies its 24th position and the relays QR1, QR4 are energized in series through the selected contacts of the switches RLS3, RLS4 at the substation. The relay QR1 illuminates a lamp L1 and thereby indicates that the correct selection is effected and the relav QR4 energizes a relay GR1, Fig. 3, which prevents transmission of supervisory signals from this substation to the control station. The ejecting key at the control station must be restored to normal to open the circuit of the relay QR4 before supervisory signals can be transmitted. Operation of circuit breaker. The common control key OK is now operated and a circuit is completed over the line 40, contact 41 of the relay QR4, the selected contact of the switch RLS3, conductor 40, the " closing " magnet of the selected circuit breaker, conductors 43, C5, to line 18A. Operation upon depression of wrong selecting key. When the despatcher operates the wrong key, the system functions in the manner previously described, but the illumination of the corresponding check lamp informs him of the incorrect operation. The key is therefore restored and the circuit of the relays QR1, QR4, which have been energized in series, is broken. The relay QR4 retracts its armature 46 and together with the armature 47 of a slow acting relay SR4, which is maintained energized during impulse transmission, closes the circuits of relays RR3, RR4, Fig. 4, which operate the magnets M3, M4 so as to restore the switches RLS3, RLS4 to normal. The relays RR3, RR4 also open the locking circuit of the relay COR1 and restore the apparatus at the substation to normal in readiness for the receipt of a fresh selecting signal. Signalling automatic opening of circuit breaker. Assuming circuit breaker No. 2 opens automatically, a contact CB2, Fig. 3, associated with the breaker is closed to energize a relay OR2 and connect battery to the fifth contact in the path of wiper W5A. A relay QR5 is also energized momentarily to operate the relays SR5, COR2. The relay COR 2 disconnects the apparatus shown in Fig. 4 from the lines and connects thereto the apparatus shown in Fig. 3 for transmitting to the control office a signal indicative of the position of the circuit breaker. The relay SR5 operates the stepping magnet M5 and also a relay QR6 over a circuit including the wiper W5A and the first contact in the bank of contacts associated therewith. The relay QR6 transmits an impulse of such polarity that the polarized relay PR2 at the control station is operated to energize a relay QR7 which connects, through the consequent action of a relay SR7, the lines to the relays PR3, QR8 and disconnects the lines from the control apparatus, Fig. 1. The relay QR7 also operates the relay LR1 of an alarm CBA which informs the operator that a circuit breaker has come out. The relay LR1 locks up and maintains the operation of the alarm until it is rendered inoperative by a kev 79. The polarized relay PR3 remains unaffected by this impulse but the relay QR8 energizes the stepping magnet M6 of the switch RLS6. When the magnet M5 at the substation is energized, the contacts 60 are opened and the relay SR5 is deenergized. The circuit of the magnet M5 is opened and the switch RLS5 is stepped forward and the relay QR6 is de-energized. The line circuit is opened at the contacts 62 of the relay SR5 and the relay QR8 at the control office is de-energized to allow the switch RLS6 to move forward through one step. When the magnet M5 is de-energized, the contacts 60 are again closed and the relay SR5 is energized to send over the lines an impulse which is of a polarity opposite to that of the first impulse due to the de-energization of the relay QR6. This impulse energizes the relays PR3, QR8 but has no effect upon the relay PR2. The relay PR3 closes a circuit for a relay R1A associated with the supervisory lamps of the first circuit breaker over the wiper W6B. The relay R1A is however without effect, since the relay R11 is de-energized in consequence of the " closed " position of breaker No. 1. The relay SR5 also energizes the magnet M5 and the switches RLS5, RLS6 are moved a second step. The switches are thus moved forward step-by-step until the marked contact on the switch RLS5 is reached, when the relay QR6 is again operated and an impulse of reverse polarity is transmitted to cause the energization of the relays QR8, PR2. The relay PR2 now closes a circuit over the wiper W6A to the relay R12 which locks up over the contact of t