. Electrical world. 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,
. Electrical world. 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. General View of Potentiometer. coils, and another, R, along the straight wire. The reading of theinstrument in the position shown is The pairs of points whosepotential differences are to be compared are connected to the blocksof the double pole switch, K, whose levers, M N, connect them, onepair at a time, to the sliding contacts, Q R, through the galvanometer key, H, is arranged to complete the circuit through by removing a sliding bottom. Nearly all the measurements madeinvolve the use of a standard cell, and one pair of terminals, the pair,A, is assigned to its connections to save confusion in working. Fusesof fine wire are inserted at all terminals except those for the gal-vanometer to save the instrument coils in the case of an accidentalconnection to a source of high pressure. 0-1 Calv: - OAO OBO OcO
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Keywords: ., bookcentury1800, bookdecade1880, booksubjectelectri, bookyear1883
