Patent GB-452135-A (GB)
Title: Improvements in measurement apparatus
IPC: G01R13/00
Filed: 1934-11-15
Abstract: 452,135. Current, pressure, and power meters. CHILOWSKY, C., 15, Rue du Lunain, Paris. Nov. 15, 1934, Nos. 32945 and 32946. Void [Abridged as open to inspection under Sect. 91 of the Acts, May 16, 1935]. [Class 37] [See also Group XIX] The pointer is carried by a rectilinear portion of a wire wound around a pulley which is given an angular displacement either directly or indirectly by an electric, magnetic, or electromagnetic field. As shown in Fig. 1, a wire 3 passes over a grooved pulley 4 and carries at one end a pointer 8 moving in front of a rectilinear scale 10, and at the other end a soft iron rod 1 attracted into a solenoid 2 against the action of a spring 9. In the construction shown in Fig. 2 the wire is wound round a pulley 12 and the ends are fixed in grooves in smaller pulleys 13, 16. A second wire, carrying the pointer, passes over grooves of larger diameter in the pulleys 13, 16 and is fixed to the pulleys at its ends, thereby giving a magnified motion to the pointer. The disc 12 may form the eddycurrent disc of an induction type instrument, and may be a plain conducting disc or may be constructed of two flat frames or elements 17, 19, Figs. 3 and 4, each in the form of a circular segment. These frames are provided with windings and are mechanically connected by insulating material and carried by a spindle 18. The whole forms a disc having a groove 21 in which the wire passes. Windings 22, 221, 23, 23<1>, 25, 25<1>, 26, 261 produce magnetic fields which act on the disc to produce a torque. The magnetic fields are reinforced by piles of soft iron sheets 20. Such a construction may form a three-phase wattmeter. Two such instruments may be arranged as shown in Fig. 5 so as to occupy a minimum space. In an alternative construction, Fig. 7, the larger pulley or disc is replaced by a cylinder 41 having a groove to take the wire, which passes also over smaller pulleys 43 and carries the pointer 42. The cylinder 41 is turned against a coil spring by the action of electromagnets 37 carrying pressure windings 105 and current windings 106, the magnetic circuit being closed by plates 38 inside the cylinder. The whole of the apparatus, with the exception of the electromagnets 37, is enclosed in a fluid-tight casing 44 of cellulose acetate or other plastic material. This is filled with a liquid such as carbon tetrachloride or an aqueous solution, a float 39 being provided to balance the weight of the movable part immersed in the liquid. The casing may be reinforced by metal, the parts 36 opposite the electromagnets being reinforced by a perforated metallic plate or made of metallic plates the edges of which are joined in a fluid-tight manner to the remainder of the casing. In a modification two cylinders 41 are provided with their axes parallel, the wire carrying the indicator passing over both cylinders. When the length of the scale is greater than the periphery of the disc, two independent wires may be provided, wound in helical grooves in which their ends are secured. An illuminating device for the pointer is shown in Fig. 12, in which concave mirrors 55, 56 project light on to the pointer 59. The pointer may be of the shape shown in Fig. 13 so as to reflect the light rays on to the scale and the wall of the casing. Fig. 14 shows a construction in which a circular scale is used. A pulley 63 driven by the movable system drives a smaller pulley 61 through a fine tungsten or other wire so as to give an amplified movement to the pointer 62.