. Journal of electricity, power, and gas . M (6 C- <% ~^ JSL ( 1 CD(^ ^ .^L O p. -^ M_ CD6 <^ M f \ o Fig. 76. A. C 394 JOURNAL OF ELECTRICITY, POWER AND GAS [Vol. XXIV—No. 17 facilitate Inandling- and also prevent breakage. Theindicator can also be applied to motors driving- ma-chine tools, etc., to ascertain whether or not they arebeing operated in excess of their guarantees. Around the upper, or left hand bulb, shown inFig. 76, and in close thermal contact with it, is a bandof resistance wire through which passes the main linecurrent or a proportionate part thereof; shunts beingprovid
. Journal of electricity, power, and gas . M (6 C- <% ~^ JSL ( 1 CD(^ ^ .^L O p. -^ M_ CD6 <^ M f \ o Fig. 76. A. C 394 JOURNAL OF ELECTRICITY, POWER AND GAS [Vol. XXIV—No. 17 facilitate Inandling- and also prevent breakage. Theindicator can also be applied to motors driving- ma-chine tools, etc., to ascertain whether or not they arebeing operated in excess of their guarantees. Around the upper, or left hand bulb, shown inFig. 76, and in close thermal contact with it, is a bandof resistance wire through which passes the main linecurrent or a proportionate part thereof; shunts beingprovided with high capacity direct current Fig. 77. Fig. 76. and current transformers with the larger sizes for useon alternating current circuits. The current in pass-ing through the resistance band heats the air in theglass bulb, which in turn causes the air to expand,thereby forcing the liquid up into the right-hand tube,the liquid then falling into the central or index tube,which is set in front of the scale. The heat generatedin the resistance band is proportional to the squareof the current passing through it (watts dissipated inresistance = resistance X the square of the currentflowing). The difference in temperature of the air in thetwo bulbs causes the liquid to flow as it does, andsince any external temperature afifects the air in the two bulbs similarly, no error will result due to changesin temperature of the surrounding air. The tube is reset by simply tilting it and allowingthe liquid to flow out of the tube back in to theU tube. In resetting the indicator, air bubbles fromone arm of the U may be carried o
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Keywords: ., bookcentury1800, bookdecade1890, bookidjo, booksubjectelectricity
