Patent GB-190000184-A (GB)
Title: A New or Improved Method of Determining the Voltage Obtaining at a Near or Distant Part of an Electric Circuit, or the Average Voltage Obtaining at Several Parts thereof, & Apparatus therefor.
Inventor: FIELD MICHAEL BIRT
Filed: 1900-01-03
Granted: 1901-01-03
Abstract: 184. Field, M. B. Jan. 3. Current meters. - Multiple wire or feeder systems are provided with means for indicating pressures at distant points. One arrange-- ment is shown in Fig. 2 as applied to three pairs of feeders B, B<1>, B', supplied through main switches C, a single Weston or other voltmeter F being connected by a controller switch L, L<1> to indicate the pressure at the distant ends of either pair of feeders, or the average of these pressures. In each pair of feeders, a divided resistance K', K' is connected between the supply ends with an intermediate wire K to one of the brushes of one half L' of the switch, and a main resistance D is connected by a wire E through a resistance H to a corresponding brush on the other half L. The terminals of the volt-meter are connected to brushes f, f<1>, and the movable contacts L, L' are arranged so that the volt-meter can be connected with either or all of the pairs of wires E, K, to give the desired indications. The parts of the resistance K<1>, K<2> are in the ratio of the resistance D to the resistance of the pair of feeders ; the resistance D may be a part of the feeder itself. When all the wires E, K are connected, a resistance M is placed in parallel with the volt-meter, to compensate for the lowering of the total resistance due to the parallel connection of the resistances H. The contacts L, L<1> may be arranged to connect any desired groups of feeders ; if these are all connected with equal resistances H, the shunt resistance M can be dispensed with. This arrangement may be simplified by placing the main resistances D between the main switches C and the supply bars A, A. The controller switch is then replaced by a plain switch, the movable arm of which is connected to the volt-meter, and the contacts directly to the wires E, another contact being connected through separate resistances to all these wires, for the average indication. A contact may be connected directly to the supply bar, to give the station pressure. The separate divided resistances are replaced by a single one connected between the supply bars, the intermediate wire being connected to the second terminal of the volt-meter. With this arrangement the average indication is inaccurate unless all the supply switches C are closed. Fig. 6 shows another arrangement, as applied to a three-wire system C', C<4>, C<5>, supplied only from two generators U, U<1>, using two volt-meters F, two divided resistances K<1>, K<2>, and three main resistances D, D', D'. Fig. 3 shows another arrangement, applicable to any two feeders C<3>, C' in a multiple system, independently of the directions of the currents. Two divided resistances are connected crosswise between the ends of main resistances D, D<2>. The volt-meter F is connected between the divided resistances. A balancing resistance K<5>, equal to that of the volt-meter, may be connected between symmetrically-placed points on the divided resistances. Electrometers.-A low-pressure electrometer may be used to indicate the pressure between distant parts of two high-pressure feeders. The divided resistance is replaced by two condensers in series ; a part of one of the feeders is used as the main resistance, in order to obtain proportional impedance, a pilot wire being brought from the distant end of this part to the electrometer, the other terminal of which is connected between the two condensers. When this arrangement is used on a multiple-wire system, the pilot wire must be placed equally near the different wires in successive parts of the system.