. Cassier's magazine . be obtained by run-ning the motor light at its normalvoltage and frequency and takingreadings of current and watts fromwhich the no-load power factor maybe calculated. The short-circuit test is made bylocking the rotor and taking readingsof primary current, watts and volts,and when the capacity of the motoris not too great to permit the currentto be conveniently measured and themotor is not liable to be dangerouslyoverheated, this test should be madeat the normal voltage; but in caseswhere it is necessary to use a lowvoltage the value of the current andwatts at the norma
. Cassier's magazine . be obtained by run-ning the motor light at its normalvoltage and frequency and takingreadings of current and watts fromwhich the no-load power factor maybe calculated. The short-circuit test is made bylocking the rotor and taking readingsof primary current, watts and volts,and when the capacity of the motoris not too great to permit the currentto be conveniently measured and themotor is not liable to be dangerouslyoverheated, this test should be madeat the normal voltage; but in caseswhere it is necessary to use a lowvoltage the value of the current andwatts at the normal volts may becalculated from the fact that the cur-rent is directly proportional to, andthe watts vary as the square of, thevoltage. A knowledge of the pri-mary resistance is also necessary, sothat the voltage drop in the primarywinding may be calculated. The circle diagram constructedfrom data given by these tests willassume the form of that shown inFig. 2, which, although developedfrom the diagram in Fig. I, differs. FIG. 2. CORRECTED CIRCLE DIAGRAM TESTING INDUCTION MOTORS 73 from it in having been corrected toallow for all losses taking place in amotor. Referring to Fig. 2, O V is theterminal voltage and O C± the pri-mary no-load current, consisting of amagnetizing component, O C2, andand energy component, C1 C2. Theshort-circuit or locked current is rep-resented by O. C I, and the semicircledescribed from centre K on base lineO B must pass through the points Ctand C I. This represents the circleof input, and all lines drawn fromthe point. O to the arc of this semi-circle will represent the primary in-put current, which may have anyvalue between the no-load current C±and the locked current CI. If weconsider one particular value of theprimary current O C, this consistsof the magnetizing component O C2,an energy current C E, and a leak-age component E C2. There is alsoanother component, C C2, whichserves to balance the secondary cur-rent. The ordinate C E representsthe rea
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Keywords: ., bookcentury1800, bookdecade1890, bookpublishernewyork, booksubjec
