. Electrical world. meter. The Crompton form of potentiometer, shown in the accompanyingillustration, has been largely adopted in English lighting and powerstations as a standard for verifying apparatus of all kinds, and formeasuring the output of the machines and stations. It also formspart of the equipment of many technical schools and laboratories. along the scale wire, can be continuously altered, and the operator isable to obtain a galvanometer balance against a standard cell whenthe reading of the sliders is that of the known of the cell atits actual temperature. If, for example,
. Electrical world. meter. The Crompton form of potentiometer, shown in the accompanyingillustration, has been largely adopted in English lighting and powerstations as a standard for verifying apparatus of all kinds, and formeasuring the output of the machines and stations. It also formspart of the equipment of many technical schools and laboratories. along the scale wire, can be continuously altered, and the operator isable to obtain a galvanometer balance against a standard cell whenthe reading of the sliders is that of the known of the cell atits actual temperature. If, for example, the temperature of the cellbe 15°, so that its is volt, the sliders may be set to thatreading, and the galvanometer brought to zero by adjusting the re-sistance, D E, and the rheostat, F. When this has been done thescale readings at all points are direct readings in volts. A view of the potentiometer is given in Fig. 2 and a diagram ofits internal connections in Fig. 3. Here ab is the scale wire; c the. ofaoo -DI.\GRAM SHOWING CONSTRUCTION OF INSTRUMENT. The construction of the instrument is diagrammatically representedin Fig. I. The calibrated wire is arranged in 14 coils, called potentiometercoils, lettered A B, and a straight section, B C, called the scale wire,the resistances of the several coils and of the straight section beingequal. One sliding contact, Q, moves over the terminals of the 14 FIG. 4.—CONNECTiONi FOR TEST UF SUFFLY MAINS. the set of equal potentiometer coils in series with it; d is the doublepole switch connecting the 6 pairs of terminals, A B C D E F, in suc-cession to the slide contacts; e f are the resistance coils and rheostatrespectively, and G is the galvanometer key. All the moving contactsare under glass, and the coils and the scale wire are inside the box itself is completely closed, but the inside can be inspected
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
