Patent GB-179174-A (GB)
Title: Improvements in apparatus for producing and controlling movements at a distance
IPC: G01C3/10
Filed: 1922-04-26
Abstract: 179,174. Schneider et Cie. April 27, 1921, [Convention date]. Void [Published under Sect. 91 of the Act]. Tell-tale apparatus. -In an arrangement for indicating when a movable member, such as a gun, has a position corresponding with that of another and distant member, such as a range transmitter, a three-phase generator 5 supplies stators 1, 3 at the transmitting and receiving stations respectively. A singlewinding rotor 2 at the transmitter is in circuit with a winding 7 of a phase-meter 9. A similar rotor 4 at the receiver, mechanically connected with the gun &c., is in circuit with another winding 8 of the phasemeter. When the rotors 2, 4 are in corresponding positions, the pointer 6 of the phasemeter is held at the zero mark by a spring, but is moved therefrom when a difference of phase arises due to the rotors 2, 4 not being in corresponding positions. In a modification, the stators are replaced by annular rheostats supplied with current at three equidistant points, and the rotors are replaced by rotary contact brushes which tap the rheostat at adjustable and diametrically-opposed points. Fig. 3 shows a method whereby a stator winding 2<1> may be supplied at six points with current from a three-phase source 5 through a transformer having a star connected primary 15 and open delta secondary 16. A modification is described in which the stator winding comprises a closed delta winding combined with a star winding. When used to communicate with a number of receiving stations from a common 'transmitter, the transmitter rotor has equally spaced windings corresponding in number with the number of receivers, the windings being respectively connected with the phase-meter windings at the receivers. Each receiver rotor has a similar number of windings, one of which is connected with a phase-meter winding, and the other windings are in closed circuits with corresponding auxiliary windings having the same selfinduction and resistance as the phase-meter windings. If desirable in order to reduce the number of connecting rings, the windings referred to above as being on the rotor may be on the stator, the rotor being supplied with the three-phase windings connected to the supply 5. The rotor windings may be arranged to form a closed circuit, tapped at points equally spaced apart, as in Fig. 6, which shows six tapping points. Two pairs of points supply current from the transmitter rotor to the phase-meter coils 7<1>, 7<11> respectively, and the third pair are connected through an auxiliary coil 25. The rotors of the two receivers shown also have three pairs of tapping points, one of which is connected to the phase meter coil 8<1> or 8<11>, the other two being connected through auxiliary or balancing windings 23<1> 24<1>; 23<11>, 24". With the above arrangements, a break-down at one receiver does not interfere with correct operation of the other receivers. Where greater accuracy is required, duplicated apparatus is used, geared together so that one makes a number of revolutions to each revolution of the other, and the pointers of the duplicate phase-meter at the receiver move over a single scale. The phasemeters may be replaced by wattmeters or other devices capable of indicating phase-difference.