. Elektrische Welt. Rechtsanwälte waren anwesend. Vier reden gegen theassumption durch die Regierung in Kraft gemacht Teilnehmer zu fein, und mit 180 Stimmen gegen 20 Telefon Administration wurde scath zunehmend kritisiert. 966 elektrische Welt und Ingenieur. Vol.XLIII, Nr. 21. Messung des Isolationswiderstandes der anElectric Leitungsnetz. Von Edwin F. Northrup. Der Schriftsteller hatte vor kurzem Gelegenheit zu Messen der Isolierung werden - jeder bus-bar und der gasleitungen der Verkabelung tween systemof eine große Stadt Bürogebäude in einer Zeit und unter circumstanceswhere war es nicht möglich, die auf Th geschlossen

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. Electrical world. lawyers were present. Four speeches were made against theassumption by the government of power to fine subscribers at will, and by 180 votes against 20 the telephone administration was scath-ingly censured. 966 ELECTRICAL WORLD and ENGINEER. Vol. XLIII, No. 21. Measurement of the Insulation Resistance of anElectric Wiring System. By Edwin F. Northrup. THE writer recently had occasion to measure the insulation be-tween each bus-bar and the gas pipes of the wiring systemof a large city office building at a time and under circumstanceswhere it was not practicable to shut off the power. The measurement was made by two methods. As these methodsare both generally applicable for determining the insulation resist-ance of each side of any wiring system while the power is on, wehave deemed them to be of sufficient value to warrant description. I.—VOLTMETER METHOD. Let A (Fig. l) represent any wiring system in which X^ and X„are the insulation resistances between the bus-bars, B^ and B„ and. II vw^AAA/Wv^A^wwJ•^^^7^AJ^AAA^AAAAA/^/J^A/v^/A^AAA/»^ V measured by this method and we may resort to the second methodto be described. Having taken the above three readings, it can beshown that g {E- - FJX, = ^ (I) A„ = (£ - l - VJ (2) The current, /, which leaks to the ground will be: / = ^1 + ^2In the particular case above referred to, in which the insulationresistance of the wiring system of a large office building was deter-mined by means of a Weston voltmeter, the following readings andresistances were obtained: g = 12, 220 ohms, £ = 113 volts, F, — I volt, Fj := 4 volts. 12, 220 (113 — I — 4) X = = 329, 940 ohms, 12, 220 (113 — I — 4)X„ = = 1, 319, 760 ohms. The above example shows that where the sum of the resistances, X and X„, are not over one or two million ohms, the voltmetermethod is sufficiently accurate for the purpose. If one side of theline is grounded—that is, if X^ = o—then from (2) £ = F^ -f- F, :=Fj, as F, = o, and the met

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• bookcentury1800
• bookdecade1880
• booksubjectelectri
• bookyear1883