Patent GB-344827-A (GB)
Title: Improvements in or relating to remote metering systems
IPC: G08C19/22
Filed: 1929-11-29
Abstract: 344,827. Protective cut-out systems. REYROLLE & CO., Ltd., A., Hebburn-on- Tyne, LEESON, B. H., Waverley, Tynemouth, HARLE, J. A., 221, Jesmond Road, Newcastle-on-Tyne, and LAMBERT, D. E., Sholebrook, Sauncey Avenue, Harpenden, Hertfordshire. Nov. 29, 1929, No. 2888/31. Divided on 344,484. [Class 38 (v).] A system for obtaining at a control station an indication of the readings of a meter at a remote station, which system may be used for indicating faults in connection with impedance or like protective systems, comprises the combination with a device moving over the meter scale at the remote station, of an indicator device moving over a corresponding scale at the control station, means for driving the two devices at corresponding speeds, and means whereby alternating or oscillating signalling currents of suitable frequency transmitted between the two stations cause the simultaneous starting of the two devices at corresponding scale positions and the simultaneous stopping of the two devices when the first device reaches the position occupied by the meter pointer. The signalling currents may be transmitted directly over an alternating current channel of communication connecting the two stations, as, for example, a long distance telephone circuit, or the transmission may be effected by means of high frequency currents by direct transmission of these currents or by modulating a carrier-wave system at suitable frequencies. In the construction shown in Fig. 1, the meter pointer 20 at the remote station is provided with a contact 21 located between two contacts 26, 27 on a timing device 25 which is adapted to be driven, through gearing, from a member 32 of a reversing clutch. The members 33, 34 of the clutch are directly coupled to a constant-speed driving element 35, and are adapted to engage the member 32 according to whether coil 36 or 37 is energized. The control station is provided with similar driving means for use in driving a pointer 50 across a scale corresponding to the meter scale. The energization of the coils 56, 57 is controlled by receivers 86, 87 tuned, respectively, to the frequencies of alternating current generators 76, 77 at the remote station. Movement of the pointer 20 in a forward direction completes, at contacts 21, 26 a circuit through battery 75, coil 36 and relay 70 The clutch then operates to drive the timing device 25 until the contacts 21, 26 separate, and relay 70 at contacts 72 connects generator 76 to the channel of communication 80 whereby receiver 86 responds and energizes coil 56 to cause movement of the pointer 50. This pointer moves in synchronism with the pointer 20. In the arrangement shown in Fig. 2 the meter readings are obtained intermittently at the will of an operator. The meter pointer 100 is provided with a contact 101 co-operating with a contact 111 on a timing device 110 which is adapted to be driven over the meter scale against the action of a spring. A similar device 130 is provided at the control station and coaxial therewith is an indicator 140 which is driven by the device 130 against spring means, and is provided with an electromagnetically-released clamp for holding it in position when not engaged by the timing device. At the remote station a generator 176 and receiver 175 are provided for co-operation, respectively, with a receiver 165 and a generator 160 at the control station. To obtain a reading, the operator presses the switch 151, whereby the clutch coil 138, the clampreleasing coil 145, and a relay 155 are energized. This relay at contacts 157 connects the generator 160 and the channel of communication 170 whereby the receiver 175 acts to energize the clutch coil 118. The devices 110, 130 are now driven synchronously until contracts 111, 101 engage, whereupon the generator 176 is connected to the channel 170 so that the receiver 165 acts to energize relay 166, this relay at contacts 167 opening a circuit so that the energized coils and relays are de-energized. The timing devices 110, 130 return to normal, the pointer 140 remaining in the indicating position. In applying the invention to remote fault position indication in connection with impedance or like protective systems, the initial operation of a protective relay in response to a fault may be caused to start the movement of a timing device at a control station, the device being stopped when the relay contacts for tripping the circuit-breaker are operated. The circuits are so arranged that the timing device is reset to zero in the event of the fault being cleared by another protective relay elsewhere on the protected circuit. The control room is provided with a number of indicators associated, respectively, with protective relays, the clearance of a fault causing the indicator associated with the relay nearest the fault which operated its circuitbreaker, to give an indication of the fault position. Specification 334,263, [Class 40 (i), Electric signalling systems &c.], is referred to.