Electrical instruments and testing; how to use the voltmeter, ohmmeter, ammeter, potentiometer, galvanometer, the Wheatstone bridge, and standard portable testing sets (1907)
Schneider, Norman H. (Norman Hugh), Hargrave, Jesse · New York, Spon & Chamberlain; [etc., etc.] · leaf 71
Fig. 36. 48 ELECTRICAL INSTRUMENTS. As an example of close reading, a change of 1ampere may be detected on an instrument readingto 1200 amperes at any point in the scale. Most switchboard instruments are calibrated fora temperature of 90° F., the error amounts to oneper cent, for a change of 10° F.… … Fig. 37. rise and decreased by a fall of temperature. Theinstrument therefore reads lower for an increaseof temperature than the actual e.m.f. and vice versa. Duplex Instruments. Most of these instruments,Fig. 37, consist of a voltmeter and an ammetercombined in one case. VOLTMETERS AND AMMETERS.…
Electric testing · Electric apparatus and appliances
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