Patent GB-190216394-A (GB)
Title: Improvements in or relating to Electric Resistances, and to the Method of using the same for Electrical Measurements.
Inventor: ADDENBROOKE GEORGE LEONARD
Filed: 1902-07-23
Granted: 1902-10-16
Abstract: 16,394. Addenbrooke, G. L., and Robinson, L. July 23. Resistance coils.-High resistances, and low resistances for large currents, are constructed so as to keep down and balance self - induction and capacity, and are arranged in boxes with contacts and rotatable switches, high - pressure terminals, and large current couplings, for use in measurements of electric alternating or other r power, pressure, or current with electromagnetic or electrostatic instruments, as described in Specifications No. 25,752, A.D. 1898, No. 20,862, A.D. 1899, No. 11,847, A.D. 1901, and No. 11,165, A.D. 1902. A high resistance, shown in end view in Fig. 3, consists of insulated wire a wound in a single layer across a long sheet of glass c, having two narrow strips of wood c<1> extending along the middle. The wire is attached to loops of thick copper wire at the ends of each coil. Several of the plates c are held between grooved supports d' in a box, each plate carrying one long coil or a number of short coils ; the copper wires are connected to contacts arranged circularly under switch arms on one end of the box. When the resistance box is used to divide a very high pressure, the terminals of the larger resistances are constructed as shown in Fig. 14. A metal block m<2> is secured by a screw m<3> in a vulcanite block m, which is fixed in an angle of the box, in connection with two vulcanite bushes. The metal block m<2> has a slit to receive the soldered connection to a resistance, a perforation to receive a conductor through the bush m<4>, and a screw-threaded hole to receive a binding-screw m<1>, provided with a non- conducting handle. A vulcanite number plate is fixed in front. A low resistance consists of a metal plate doubled over one edge of a slate, and attached to two gun - metal angle - pieces, provided with binding-screws, on opposite surfaces of the slate. The metal plate is immersed in oil iu a flat zinc box and this is surrounded by water in a larger box, the angle-pieces being supported bv two covering-strips. In another construction, Fig. 9, several resistant metal rods and corrugated plates e are extended between holding-bolts on two metal bars g, g', each of which carries a binding-terminal. The bars g, g<1> are connected mechanically by rods, and are supported by blocks slid into guides in a box. The plates and rods are all connected electrically to the lower bar g<1>, and insulated from the upper bar g. Any resistance may be electrically connected between the bars g, g<1> by screwing down a socket h<1> on its upper holding-bolt to bear on the bar g. The sockets h<1> are inserted through holes in the box j, the screws, sockets, and holes being of several sizes. Electrometers.-In making power measurements, two quadrants are connected to the ends of a low resistance inserted in one main. An adjusted portion of the high resistances is connected between the mains, a fixed part of it being situated between the low resistance and a connection to the needle of the electrometer. In a modified arrangement of connections, Fig. 16, the two quadrants n<2> are connected directly to the ends of the main current resistance e, and through two fixed high resistances A', A' to the needle n<1> of the electrometer, which is also connected by the adjustable high resistances a to the other main.