Patent GB-699101-A (GB)
Title: Improvements in or relating to electrical measuring and/or repeating instruments andrelays
IPC: G08C19/06
Filed: 1950-11-21
Abstract: 699,101. Telemetering. NALDER BROS. & THOMPSON, Ltd., and LIPMAN, C. L. Feb. 20, 1952 [Nov. 21, 1950], No: 28475/50. Class 40 (i) Dynamometer moving coil instruments ' of known form are adapted to serve as telemetering or telecontrol transmitters so that each of the latter essentially comprises a voltage-producing coil embracing and movable along a ring-shaped or arc-shaped magnetic core and in an alternating or pulsating magnetic field. In Fig. 1 the transmitter T and receiver R are of identical electrodynamic construction and are designed on the basis of a disclosure in Specification 469,938, [Group XXXVI]. In T the coil MT embraces and moves around a ring-shaped magnetic core CPT and in an air gap permeated with alternating flux produced by A.C. energized stator coil FT. The coil MT shares a spindle with an initiating instrument I so that as the latter is actuated by active or reactive power, voltage or other quantity, the coil MT is correspondingly moved and in accordance with its angular position generates a voltage representative of the prevailing value of the quantity indicated by I. This voltage energizes transmission lines 13, 14 and produces follow-up or repeat movement of coil MR in receiver R. For applications wherein a receiver such as a relay, contactor or trip coil cannot be or is not required to be actuated until a predetermined deflection in the initiating instrument I has occurred, the magnetic core CPT may be of stepped or tapering. cross section, Figs. 6 and 9, so that the output emf of the coil MT remains substantially zero for a short range of deflection either way from the centre zero and zero emf position and then suddenly climbs to a relatively high value. With a core CPT of constant cross section the same result may be achieved to a more limited extent, i.e. for slight deflections from zero of instrument I, by making the receiver comprise a rectifier insensitive or incapable of rectification at low voltages. The Specification includes the output characteristic curves with and without rectification, Figs. 4 to 10 (not shown) corresponding to the constant and varying cross section cores. The tapering core of Fig. 9 is used in the electrodynamic instrument described in Specification 530,698, [Group XXXVI], and this instrument, comprising two moving coils connected in opposition, is adapted as a transmitter in two further arrangements. In one of these, Figs. 12-13 (not shown), the output emf developed by the transmitter is applied through a bridge rectifier to two independent receivers each corresponding to R in Fig. 1 and with their moving coils connected in series. In the other arrangement, Fig. 14 (not shown), a transformer at the receiver point energizes both the transmitter and the receiver electromagnets. In Fig. 15 (not shown), the transmitter used is based on a design described in Specification 696,821, [Group XXXVI], In Fig. 16 the transmitter employs a sandwich arrangement of core plate and pole pieces similar to the selected constructions described in Specifications 530,698, 627,327 and 696,821, [all in Group XXXVI]. The multistage equipment shown in Fig. 17 employs coreplates as described in Specification 696,821', [Group XXXVI]. In the transmitter T the moving coil MI, mechanically coupled to voltage-producing .coil MT, is responsive to varying A.C. voltage across lines YY. Thus for any given YY voltage there is a corresponding emf generated by MT and this emf is applied via lines 26, 27 to a follow-up coil MR in receiver R. The coil MR in receiver R is mechanically coupled to a voltage-producing coil MT' and the output from MT' is applied to a further stage and so on. A stabilizer CV feeds constant A.C. voltage to the transmitter and receiver field windings. In the equipment shown in Fig. 19, the transmitter coil MT is moved proportionately to torque or watts of an initiating wattmeter I and emf generated is rectified and applied to remote receiving units comprising indicating. instruments U<SP>1</SP>, U<SP>2</SP>, a graphic recorder U', a relay U<SP>4</SP> and also locally to a moving coil MB of a balancing instrument B which produces an opposing torque balancing the torque exerted by wattmeter I on common spindle S. Fig. 19 may be modified Figs. 20 and 21 (not shown) so that the arrangement comprises an initiating and transmitting instrument as IT in Fig. 17 and a balancing instrument of the permanent magnet moving coil type disclosed in Specification 452,440, [Group XXXVI]. The damping employed for the various instrument movements may be as described in Specification 574,894, [Group XXXVI], and illustrated at D, Fig. 1. A receiver instrument of the moving magnet type disclosed in Specification 629,299, [Group XXXVI], may be used. The transmitter output emf may be. amplified. Summation of a number of separate initiating readings may be accomplished by connecting the moving coils of the separate transmitting instruments in series with the single moving coil of a receiving instrument. Specification 456,988, [Group XXXVI], is referred to.