Patent GB-344484-A (GB)
Title: Improvements in or relating to remote metering systems
IPC: G08C19/22
Filed: 1929-11-29
Abstract: 344,484. 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. 36646. [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 a device moving over the meter scale at the remote station, an indicator device moving over a corresponding scale at the control station, means for driving the two devices at corresponding speeds, means whereby these devices are started simultaneously from their zero scale positions and are stopped simultaneously when the first device reaches the position occupied by the meter pointer, and means whereby after the desired information has been given the devices automatically return to their zero positions, where they remain irrespective of any movements of the meter pointer until a new indication is to be obtained. In the construction shown in Fig. 1, the meter pointer 100 carries a contact 101 for co-operation with a contact 111 on a timing device 110, which is adapted to be driven, against spring action, by a constant-speed driving element 115 acting through a clutch 117 controlled electromagnetically by a coil 118. Similar means are provided at the control station for driving a timing device 130 coaxial with a pointer 140. The pointer is adapted to be driven over the scale, against spring action, by the timing device 130 and is held in its indicating position when not engaged by the timing device, by means of an electromagnetically released clamp (not shown) controlled by a coil 145. When a reading of the meter is desired, a hand-switch 151 is closed to complete a circuit whereby the clutch coils 118, 138 and the release coil 145 are energized. The devices 110, 130 then move synchronously over the scales until contacts 111, 101 close, whereupon relay 106 operates at contacts 107 to open the circuit of the clutch coils and release coil. The devices 110, 130 move back to zero position and the pointer 140 is clamped in position to indicate the meter reading. The system may be used with alternating currents of audio or radio frequency. In the construction shown in Fig. 2, the remote station is provided with an alternating current generator 176 and a receiver 175, the latter being tuned to the frequency of a generator 160 at the control station, which is also provided with a receiver 165 tuned to the frequency of the generator 176. The receiver 175 controls the energization of clutch coil 118, and the receiver 165 controls the operation of relay 166 for opening the circuit of clutch coil 138 and release coil 145. In applying the invention for use in impedance or like protective systems, the initial operation of a protective relay in response to a fault is caused to start the movement of a timing device at a control station, the device being stopped and returned to zero, leaving an idle pointer in the indicating position, when the relay contacts for tripping the circuit-breaker are operated. The circuits are arranged so that both the timing device and the idle pointer are set to zero in the event of a 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 operates its circuit-breaker to give an indication of the fault position. Specification 334,263, [Class 40 (i), Electric signalling systems &c.], is referred to.