This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 Excerpt: ...coil of wire of the shape of a flattened ring, and a ring of one turn of stout wire suspended by a spiral spring. The plane of the suspended ring in its position of rest is at right angles to that of the fixed ring. The two ends of the suspended ring dip into mercury cups, which allow a cur FIG. 89. SIEMENS ELECTRO ...
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This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1892 Excerpt: ...coil of wire of the shape of a flattened ring, and a ring of one turn of stout wire suspended by a spiral spring. The plane of the suspended ring in its position of rest is at right angles to that of the fixed ring. The two ends of the suspended ring dip into mercury cups, which allow a cur FIG. 89. SIEMENS ELECTRO-DYNAMOMETER. rent to be sent round it while it is still quite free to turn. The wires are connected so that a current entering the instrument passes through both the fixed and suspended coils. The ring suspended by the spiral spring has its upper end attached to a nut or button called the "torsion head.'-The latter carries a pointer, which, when the torsion head is turned by hand, moves over a scale of degrees, and indicates through what angle the top end of the spring has been twisted. When a current is sent through the instrument, the suspended coil is deflected, but is prevented moving more than about 5 degrees by a stop. The torsion head is then turned by hand until the twist or torsion of the spring, acting against the current, brings the suspended ring back to its zero position. The number of degrees through which the torsion head has had to be turned indicates the strength of the current. A table is supplied with each instrument, showing the number of amperes corresponding to each degree. The table is prepared by comparing the indications of each instrument with those of an absolute electrodynamometer, when the same currents are sent through both instruments. Some instruments have two fixed coils, one consisting of a good many turns for feeble currents, the other of a few turns for strong currents. Such instruments of course have two reduction tables. To measure a current with this Instrument, we first level the instrument carefully, ...
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Add this copy of New Dynamo Tenders' Hand-Book: With One Hundred and to cart. $56.49, good condition, Sold by Bonita rated 4.0 out of 5 stars, ships from Newport Coast, CA, UNITED STATES, published 2012 by Nabu Press.
