TransactionsPublished under the care of the General Secretary and the Treasurer . wer, which, to my mind, are perfectlyuseless. The errors you get are infinitely greater than could be causedby the most inaccurate of wattmeters. At the same time I have hadthe opportunity of testing a few of the ordinary supply meters, but Ihave not the results to show you here. Another thing I should like to refer to is the method I have been em-ploying in making these tests. The testing of instruments at variouspower-factors when it has been done at all has usually been effected withthe aid of two alternators,
TransactionsPublished under the care of the General Secretary and the Treasurer . wer, which, to my mind, are perfectlyuseless. The errors you get are infinitely greater than could be causedby the most inaccurate of wattmeters. At the same time I have hadthe opportunity of testing a few of the ordinary supply meters, but Ihave not the results to show you here. Another thing I should like to refer to is the method I have been em-ploying in making these tests. The testing of instruments at variouspower-factors when it has been done at all has usually been effected withthe aid of two alternators, the shafts or armatures of which can be setat an angle so as to give any desired phase difference. Although thisis an excellent device, it is naturally somewhat costly and difficult toobtain, and I have been therefore led to substitute for it a phase-shiftingtransformer, which, although from what I have recently heard it maynot be absolutely novel, is certainly not generally known of, and is soextremely convenient for this important class of work that it may bearmention The apparatus, in the form I have had it made, resembles an inductionmotor with a simple two-pole winding, the outer part corresponding tothe stator, being wound either with a two- or three-phase winding soas to give a pure rotating field in its center, while the center portion,which can be rotated to any desired angle, is woimd with a simple diame-tral single-phase winding. In order to obtain as regular a rotating fieldas possible, the windings should preferably be made in a considerablenumber of nearly closed slots or timnels, and the rotating portion may bemad^ to fit the stator, so that the magnetizing current is very such a device any desired phase rotation may be obtained by merelysetting the rotating part to the corresponding angle, and a fairly closeidea of the power-factor can be obtained from a permanent scale fixedto the transformer. The connections I have used, in wattmeter and sup
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Keywords: ., bookcentury1900, bookdecade1900, bookidtr, booksubjectelectricity
