Patent GB-368826-A (GB)
Title: Improvements in or relating to remote control and/or supervisory systems
IPC: H02J13/00
Filed: 1930-12-10
Abstract: 368,826. Electric signalling and remote control systems. BRITISH THOMSONHOUSTON CO., Ltd., Crown House, Aldwych, London. - (Assignees of Stewart, C. E. ; 4033, Marshall Road, Drexel Hill, Pennsylvania, U.S.A.) Dec. 10, 1930, No. 37289. Convention date, Dec. 11, 1929. [Class 40 (i).] In a remote control and/or supervisory signalling system employing selectors stepped in synchronism at a main station and a sub-station, a signal is given if a fault occurs in any of the circuits, the control circuit is opened and, where automatic controlling means is provided it is substituted for the remote control. An alarm is also given if the battery potential at the remote station falls below a predetermined value, and arrangements are made for identifying a switch in which the interlock between " out " and " in " position is faulty. The invention is described as applied to a system using four wires respectively for synchronizing, controlling, indicating and a common return, but in a second embodiment, in which no control apparatus is provided, the control line is used as a second indicating wire, indications from two apparatus units being returned simultaneously. Signalling of automatic movement of controlled units is provided. The general operation of the system is similar to that described in Specification 307,469, [Class 40 (i), Electric signalling systems &c.]. Checking indication of remote switches. To check the indicator positions the start key 6 is operated, completing a circuit from negative of 10 over i of selector A, conductor L2, i<1> of A<1> and 44 to mid-point of 13 which is connected over L4 to the mid-point of 10. Relay 44 operates and completes a synchronizing circuit over L3 including relays P, P<1> and wipers s, s<1>. Relays P, p<1> respond, completing circuits for magnets 48 and 49 to step selectors A, A<1>. Successive contacts of s, s<1> are connected to opposite poles of the batteries 10, 13 respectively so that the polarity in the line L3 changes at each step of the selectors allowing P, p<1> to re-operate and change the polarity connected to the motor magnets 48, 49. These magnets are connected to wipers n, n<1> respectively which meet opposite polarities on consecutive terminals so that the magnets operate on each energization of relays P, p<1> and step the selectors over their banks. By means of interlocks such as 35<1> the switches at the remote point connect to terminals i<1>, polarities dependent on the position of their respective switches and these polarities are connected in turn over L2 and i to relays 26 which control red and green lamps r, g to indicate the position of the respective switches. Selection and operation of a remote switch. If the operator wishes to reverse the position of the switch 1<1> the relative key 4 is moved to its opposite position and lamp w lights to indicate disconformity in the positions of the key and the remote unit. Key 3 is operated and start key 6 is depressed. The selectors A, A1 step round as previously described until position 3, corresponding to unit 1<1>, is reached when the circuit over s is broken and P, P<1> do not re-energize. Relay 53 pulls up and lamp b lights to indicate that the control circuit is extended to the correct unit. The key 7 is then operated completing a circuit over c, L1, and c<1> to control relay 26<1>, the polarity of the current flow depending on the position of the key 4. The relay 261 assumes a position relative to this current flow and the remote switch 1 is moved to the required position. When the position is reached, the direction of current flow over indicating conductor L2 is reversed and relay 26 reverses its position, reversing the indication on lamps g and n and extinguishing lamp w. The operator recloses the circuit controlled by key 3 and the selectors A, A<1> step to their normal positions. Indication of automatic operation of controlled unit. A relay 30, associated with each remote unit, is held normally energized via its own contact and the interlock 35<1>. When a switch changes over automatically this circuit is momentarily interrupted and the relay releases, completing a circuit for 36, the contact of which is in parallel with and performs the same functions as that of start relay 44. The selectors A, A<1> are started and when the position of the operated unit is reached, the polarity over L2 is such as to operate the relative relay 26 to its opposite position. The lamps g, r change over, lamp w lights to indicate disconformity between the remote switch and key 4, lamp 67 lights and alarm bell 8 is oper. ated. Alarm bell 8 is energized in response to the de-energization of 61, which falls away whenever either A or A<1> moves off-normal. The de-energization of 61 allows 42 to pull up and 63 relapses, completing a circuit for 8. Key 9 changes the operation of 8 to a single stroke bell, relay 64 energizing under these conditions to re-establish the circuit of 63. When 42 relapsed its contact 66 changed over and 70 de-energized, lighting lamp 67. This signal is extinguished by the depression of 68. Relay 42 also extinguishes lamp G, indicating the selectors are off-normal. Preventing reoperation by line surges. When the selectors regain their normal positions, surges in lines L3 or L2 may operate P, P<1> or 44 and thus restart the selectors. To prevent this slow operate relay 46 is connected in circuit with a contact of P and is energized when the selectors are normal, keeping the starting circuit closed. When the selectors are stepping 46 falls away, opening the initial circuit of P, P<1> and energizing slow release relay 47, which opens another point in this circuit. When stepping terminates a time lag occurs, whilst 46 is operating and 47 is falling away, before the initial circuit of P, P<1> is recompleted, thus allowing time for line surges to dissipate. Preventing irregular control. The terminals of relay 69 are connected, during stepping, to like polarities at the armature of P and on wiper s. When the selectors A, A<1> stop, due to s being on a disconnected contact, relay 69 energizes (over P, P<1> and s<1>) and completes a circuit for 53 (over contacts of 47) which, as already described, lights lamp b and completes the control circuit. Relay 53, on operation, short-circuits a portion of resistance 78 to make 69 more sensitive to voltage variations. Should A, A<1> be on dissimilar contacts, 69 does not energize, the control circuit is therefore not completed and the lamp b remains unlit. Relay 53 cannot be energized under these conditions until the selectors have completed a successive operation, after which the contacts of 69 and 47 are simultaneously closed to complete the circuit of 53. Line circuit faults. A fault alarm bell 8, which may be replaced or supplemented by a lamp or a drop indicator, is operated whenever relay 61 de-energizes, a similar relay 61<1> being provided at the remote station for giving a local alarm and, as described later, for switching over to automatic control. The relays 61, 61<1> are included in the circuit of L1 and L4 and should either of these lines break, the relays de-energize. The circuit also includes operated contacts of 62 and 65, which are in the circuits of L2 and L3 respectively so that an open circuit on either L2 or L3 de-energizes the relays 61, 61<1>. A short circuit between L1 and L2 shorts down 61 and may energize 44 to start the selectors, in which case 61<1> de-energizes. Relay 61 is also shorted down if L1 and L4 are connected. Relay P is operated to move A off-normal and thus de-energize 61 if short circuits occur between L1 and L3, L2 and L3 or L3 and L4. No alarm is given if L2 and L4 are shorted but as the start relay 44 is shorted out the apparatus cannot be set in operation and the fault would thus be revealed to the operator. The relays 53 and 55 remain de-energized during fault indication and maintain the control circuit open. Failure of sub-station battery. Should the sub-station battery fall below a predetermined fixed value, relay 50 de-energizes, opening the circuit of L4 which in turn de-energizes 61 and 61<1> to operate the alarm. Automatic control. Apparatus at the remote station, such as motor generators or oil switches, may be put under control of automatic control equipment, indicated at 87, by relays such as 26<11> which are normally operated from the control station in the manner previously described. This automatic equipment may, however, be brought into operation by relays 84, 85 which are operated from 61<11> by a battery (not shown). Relay 61<11> is energized every time 61<1> falls away but it is provided with a time lag sufficient to prevent it completing the circuits of 84, 85 during normal control operations. Faulty operation of interlock. Should an interlock 35<1> fail to make its contacts properly, the restoring circuit of relay 30 is not completed and the selectors A, A<1> step round continuously. Relays 61, 61<1> therefore remain de-energized and an alarm is given each time the switches regain their normal positions. The meter 86, connected in circuit with L2, enables the faulty switch to be identified, the meter reading falling when the selectors are connected with the faulty apparatus. Restoring synchronism. Should the switches lose synchronism, the key 5 is depressed, allowing the switches to step independently to normal. Relay 62 is operated by key 5 and opens the starting circuit, thus preventing the starting of the selectors until the key is restored.