Otherproblems encountered insuchmeasurementsare thoseinvolved indealing withdistorted waveshapes or in dealing withcaseswherethesystem parameters maychange

withtime. Whilethemeasurementofthelosses inalarge transformer involves a large andcomplex system, theemphasis inthis paperisuponthepowermeasurementcircuitry itself. The paperpresents a brief summaryoftheshort circuit andthe opencircuit transformer testsandofthebasicrequirements forthehigh voltage andhigh currenttransducers thatform thefront endofthepowermeasuring apparatus. Thepaper thenpoints outthetheoretical limitations ofvarious types of digital measuring methodsandindicates theseparation of thesedifficulties fromthepractical limitations ofparticular types ofcircuits. Thepaperprovides an outline oftheoperation ofsampling wattmetersanddiscusses thepotential capabilities ofsuch devices as a solution tothetransformer measurementprob¬ lem.Inaddition thepaperoutlines theresults ofa computer simulation ofsuchan instrument. Thefinal section ofthepaperexamines thebehavior of various types ofdigital wattmeters as measurementinstru¬ ments to be usedindetermining thelosses inlowPF situations. Inaddition tothesampling wattmetertheseinclude units thatperform themultiplication ofthecurrenttimesthe voltage withthermal elements, withtimedivision multiplica¬ tioncircuitry, andwithsemiconductor analog multiplier