Patent GB-562381-A (GB)
Title: Improvements in and relating to electric selective controlling apparatus
IPC: H02J13/00
Filed: 1942-11-24
Abstract: 562,381. Signalling over power circuits. BRITISH THOMSON - HOUSTON CO., Ltd. Nov. 24, 1942, No. 16641. Convention date, Nov. 28, 1941. [Class 40 (i)] [Also in Group XXXVII] An alternating current control receiver for producing a control operation in response to the reception of two current impulses having a predetermined interval between them, comprises a driving and a driven member arranged on a motor shaft with the driven member producing the control operation. These members are normally disengaged, but the motion of the driving member on receipt of the first impulse causes engagement between the members. Means are provided for de-energizing the motor in response to the second impulse, comprising a pair of impedances connected in series across the motor and means responsive to the reception of current for impressing voltage across one of the impedances and means for impressing an opposite voltage across the other impedance in all positions of the motor except its initial position, the arrangement being such that the motor is driven when either of two contacts are closed and stopped when both are closed. Receiver, Fig. 1.-Impulses of relatively high frequency on the mains 15 are received on tuned inductances 25 and after full wave rectification operate relay 24. One side of the mains is connected to a common point between two series condensers 29. 30 connected across the winding 16 of a shaded pole motor 10, the circuit comprising either condenser and the winding being tuned to the supply frequency. The motor will run when the other side of the mains is connected to one or other of the leads to the winding by relay 24 or contacts 23 to be described later, but will not run when both leads are so connected. On receipt of the first pulse, the motor starts up and drives, through gearing 20, a shaft 11 carrying a loose cam disc 14 and a member 13 angularly adjustable and driven by a pin 71 on an arm 12 keyed to the shaft but slidable thereon to enable member 13 to be adjusted. In the normal position of the device, the free end of spring contact member 41 engages a depression 42 in cam 14 and initial movement of arm 12 releases spring 40 to close contacts 23. If the impulse has not ceased, the motor stops but will restart when relay 24 relapses. Contacts 23 can be opened only when member 41 enters a depression and, simultaneously, arm 12 is in the position shown. The cam 14 has two lugs 55, 57 carrying sliding pins 58, 60 adapted to be engaged respectively by shoulders 50, 51 on member 13 during its clockwise rotation, a further lug and pin 56, 59 may be provided. When the motor is energized, pin 60 is held up by magnetic attraction of an extension 61 from the core of the motor. When. the next impulse comes in, the motor stops and restarts, and if the duration of the pulse interval corresponds with the setting of the receiver, member 13 will have been rotated to bring the recess at 51 beneath pin 60 ; the de-energization of the motor releases pin 60 from attraction by member 61, so that the cam 14 is driven by member 13 until depression 44 comes opposite the end of spring arm 41. The sloping side of the depression causes the cam to receive a small kick forward when engaged by the spring arm so that pressure of pin 60 against shoulder 51 is released and the pin drops out of engagement with member 13. The cam thus remains in the position in which the high portion 62 operates spring contacts 65 to open both sets of contacts 66, 67. If at this time arm 12 does not open contacts 23 to stop the motor, its rotation proceeds until this is effected.. To re-close the contacts 66, 67, two further spaced impulses are required, the operations being similar except that pin 58 is now in the upper position and is released by the second impulse to engage shoulder 50. The positions of the shoulders 50, 51 relatively to the arm 12 determines the pulse intervals to which the apparatus responds. If a third pin 59 is provided, the spring sut may be operated in two stages 67 being opened by the intermediate portion 63 of the cam in response i o one pair of impulses and 66 subsequently by a further pair. The operation on the first pair of impulses is as previously described except that when the cam 14 has been driven approximately 90 degrees by shoulder 51 and pin 60, recess 43 comes opposite the spring arm 42 to release the pressure between 51 and the pin 60 and the latter is withdrawn by magnet 80. The motor runs until arm 12 opens contacts 23. A subsequent pair of impulses operates similarly to effect rotation of 14 through another 90 degrees, the drive being imparted by pin 59. The spring sets may be used to control variable street lighting or low and high consumption water heaters. Modified cams and spring sets may be provided as in Figs. 2 and 3 (not shown). In Fig. 2, edge cams are used which momentarily open one switch during one half revolution and momentarily close another switch during the other half ; in Fig. 3, the operation is similar to that of Fig. 1 without the intermediate stage. Face cams may be used. Circuit arrangements, Fig. 4.-Four receivers are provided, three of which, 150, 151, 154, are in accordance with the present invention, whereas the fourth, 139-146, is as described in U.S.A. Specification 2,064,644 and opens and closes a mercury switch 146 in response to two different durations of current flow in heater 142 of a bimetallic strip 145 in response to operation of relay 141 by high frequency of different durations on the mains 130. The transmitter comprises a generator 137 driven by motor 160 and connected to the mains over a tuned circuit 161, 162 by relay 173 controlled by circuits shown in the lower half of the Figure. The impulses of different duration for controlling the thermal switch 142-146 are transmitted when switch 164, 166, 167 is in its uppermost position, switch 168 being connected to one or other of two delayed action (dashpot) relays 169, 170 providing durations. of, say, 10 to 40 secs. The motor is started by moving switch 164, 166, 167 upwards to the next contact from the position shown. When the generator is giving steady output, as indicated by lamp 174, the switch is moved to its uppermost position, whereupon the motor still runs and relay 173 is operated over contacts of relays 169, 170, one or other of which is energized in parallel to release 173 after the required delay. The motor is stopped by restoring switch 164, 166, 167 to its central position. The duration signals also cause ineffective operation of the receivers 150, 151, 154, which are, however, effectively controlled by switch 164, 167, a rotary switch 185 which times the intervals for the three receivers under control of pairs of switches 194, 195-198, 199 respectively, and a relay 178 which times the short impulses. By setting switches 194-199 in appropriate positions all three receivers can be operated during one rotation of switch 185, operation of receiver 150 in accordance with the setting of switch 194, 195 to its upper or lower position for a short or long interval will be taken as an example. Switch 164-167 is moved one step down to start the motor-generator set and subsequently to its lowermost position to initiate transmission. Switch 185 is driven by synchronous motor 184 similar to the previously described motors at the receivers, the motor being energized over switch arm 166 in its lowest position, contacts of transmitting relay 173, contacts of re-setting relay 182, switch arm 195. When switch 185, normally in the position shown, reaches contact 187, transmitting relay 173 and timing relay 178 are operated in parallel, the impulse being terminated by relay 178. A second impulse is transmitted in similar manner when switch 185 reaches contact 188 or 189 depending on the position of switch arm 194. The circuit of motor 184 is opened each time an impulse is transmitted in order that the transmitter may keep in step with the receiver which, it will be recalled, stops during the receipt of each impulse. Additional different type receivers may be associated with the space contacts associated with the wiper arm 185.