GB302396A - Improvements in or relating to electrical signalling or control systems - Google Patents

Abstract

302,396. Aronwerke Elektrizitõts Ges., and Stern, W. Sept. 16, 1927. Tell-tale apparatus.-Relates to a device for indicating at a distance the value of electrical supply, current, or tension wherein a measuring system of the electricity meter type is rotated by the supply and drives a current generator, the current, tension, or frequency of which is indicated at a distance. The generator driven by the measuring system also may be used for controlling relays. As shown, the magnitude to be measured drives, through the intermediary of electromagnets m, n, a disc a which rotates a direct current generator comprising a metal disc d provided with a winding p co-operating with magnets i. The generator is connected to an indicating instrument fthrough bushes o co-operating with a commutator e. Eddy-currents generated in the disc d provides the braking force of the apparatus. Further braking force may be provided by a magnet c acting on the disc a. A separate eddy-current brake disc may be provided, and an additional turning movement may be imparted to the measuring instrument by a separate magnet in order to provide a preliminary indication to indicate that the line wires are intact when the quantity to be measured is zero. Instead of a direct current generator, an alternating current generator may be used. Several instruments may be connected in the same circuit and operate a common indicator or integrator in order to indicate or register the sum or difference of several measurements of the same kind. Alternatively the several instruments may be connected in parallel. The indicating instrument may be adapted to give signals or perform other functions at predetermined values of the magnitude to be measured or a relay, which may be polarized, may be included in the indicating circuit for similar purposes. Several measuring instruments may.be associated with a corresponding number of indicating instruments over two line wires by means of synchronously-driven distributors. Moreover, indications may be transmitted over existing line wires, such as telephone wires. Indications of power and power factor may be transmitted to a distance by two measuring systems adapted to operate a single receiver of the " quotient or crossed coil " type. Two measuring systems also may be arranged to effect a supervisory control for the protection of cables or other electrical apparatus. For example, the measuring systems, driven at the beginning and end of a cable respectively by the current in the cable operates a single leakage indicator. Alternatively a relay is provided which is operated when the current of the beginning and end of the cable is not the same. Specification 210,045 is referred to.