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قراءة كتاب Hawkins Electrical Guide v. 3 (of 10) Questions, Answers, & Illustrations, A progressive course of study for engineers, electricians, students and those desiring to a
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Hawkins Electrical Guide v. 3 (of 10) Questions, Answers, & Illustrations, A progressive course of study for engineers, electricians, students and those desiring to a
TRANSCRIBER'S NOTE:
In transcribing this book, the proofreaders found and corrected several minor typographical errors which did not affect the sense of the text. In the caption to Figure 541, the equation for the voltage of a Weston cell at different temperatures was missing a digit "1" and this has been corrected. There is a reference to a Figure 619 but no such figure exists in the original text. There are references to a Figure 119 and a Figure 443; these presumably exist in one of the preceding volumes of the series.
HAWKINS
ELECTRICAL GUIDE
NUMBER THREE
ANSWERS
&
ILLUSTRATIONS
FOR ENGINEERS, ELECTRICIANS, STUDENTS
AND THOSE DESIRING TO ACQUIRE A
WORKING KNOWLEDGE OF
BY
HAWKINS AND STAFF
COPYRIGHTED, 1914,
BY
THEO. AUDEL & CO.,
New York.
Printed in the United States.
TABLE OF CONTENTS
GUIDE NO. 3.
Action of compass needle--simple galvanometer--difference between galvanoscope and galvanometer--sensibility--action of short and long coil galvanometers--classes of galvanometer--astatic galvanometer--tangent galvanometer--graduation of tangent galvanometer scale--table of galvanometer constants--mechanical explanation of tangent law--sine galvanometer--table of natural sines and tangents--comparison of sine and tangent galvanometers--differential galvanometer--ballistic galvanometer--kick--damping effect--use of mirrors in galvanometers--lamp and scale--damping--D'Arsonval galvanometer: construction, operation; uses--galvanometer constant or figure of merit--shunts.
TESTING AND TESTING APPARATUS 465 to 536
Pressure measurement--Clark cell--Weston cadmium cell--pressure measurement error with ordinary voltmeter--International volt--hydraulic analogy of amperes--coulombs--current measurement--International ampere--voltameters--Ohm's law and the ohm--International ohm--ohm table--practical standards of resistance--various methods of resistance measurement--direct deflection method--method of substitution--resistance box--fall of potential method--differential galvanometer method--drop method--voltmeter method--Wheatstone bridge--usual arrangement of resistances of Wheatstone bridge--ratio coils of Wheatstone bridge--the decade plan--two plug arrangement--"plug out" and "plug in" type of resistance box--testing sets--direct deflection method with Queen Acme set--[typo:ohmeter:ohmmeter]--fall of potential method with Queen Acme set--apparatus for measuring low resistances--how to check a voltmeter--Kelvin wire bridge--internal resistance measurement--Evershed portable ohmmeter set--L and N fault finder--ammeter test--diagram of Queen standard potentiometer--diagrams illustrating loop testing--the Murray loop--the Varley loop--special loop--the potentiometer--location of opens--to pick out faulty wires in a cable--voltage of cell measurement with potentiometer--care of potentiometer--location of faults where the loop is composed of cables of different cross sections.
AMMETERS, VOLTMETERS, AND WATTMETERS 537 to 572
Definition of ammeter--classification of ammeter and voltmeters--moving iron type instrument--Keystone voltmeter--winding in ammeters and volts--connections for series and shunt ammeters--voltmeter connections--Westinghouse ammeter shunts--various types of instrument--plunger type instrument--magnetic vane instrument--inclined coil instrument--Whitney hot wire instruments--principle of electrostatic instruments--multipliers--portable shunts--Siemens electro-dynamometer--station instruments--Thompson watt hour meter--how to read a meter--installation of wattmeters--Westinghouse watt hour meter--Thompson prepayment watt hour meter--how to test a meter--Sangamo watt hour meter--Columbia watt hour meter--Duncan watt hour meter.
OPERATION OF DYNAMOS 573 to 596
Before starting a dynamo--adjusting the brushes--brush position--how to set the brushes--method of soldering cable to carbon brush--brush contact pressure--direction of rotation--method of winding cables with marlin--method of assembling core discs--starting a dynamo--tinning block for electric soldering tool--shunt dynamos in parallel--shunt dynamos on three wire system--how to start a series machine--the term "build up"--how to start a shunt or compound machine--"picking up"--indication of reversed connections--how to correct reversed polarity--finding the reversed coil--loss of residual magnetism--remedy for reversed dynamo--attention while running--lead of brushes--method of taking temperature--lubrication--oils--allowable degree of heating--attention to brushes and brush gear.
COUPLING OF DYNAMOS 597 to 610
Series and parallel connections--coupling series dynamos in series; in parallel--equalizer--shunt dynamos in series; in parallel--switching dynamo into and out of parallel--to cut out a machine--dividing the lead--compound dynamos in series; in parallel--equalizer connection--switching a compound dynamo into and out of parallel--equalizing the load--shunt and compound dynamos in parallel.
DYNAMO FAILS TO EXCITE 611 to 622
Various causes--brushes not properly adjusted--defective contacts--incorrect adjustment of regulators--speed too low--testing for break--insufficient residual magnetism; remedy--open circuits--test for field circuit breakers--probable location of breaks--Watson armature discs--Fort Wayne commutator truing device--short circuits--Watson armature--wrong connections--reversed field magnetism.