International Library of Technology · Scranton, International Textbook Co. · leaf 261
ALTERNATING instrument might be so marked as to give the currentdirectly. Hot-wire instruments, in order to be reHable, must befrequently recalibrated, as the heating and cooling seem toaffect the wire, causing changes in the zero-point. On ac-count of these defects, hot-wire instruments have… … Fig. 1497.stations, and a large number of switchboard instruments ofthis type are in use. Fig. 1497 shows a Westinghouse CURRENT APPARATUS. 2635 plunger ammeter. In this instrument the conductor whichcarries the current does not act upon a magnetic needle, butupon a metal core C built of many…
Electrical engineering
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