Precise comparison method of testing alternating-current watthour meters
AH Spinks, Thomas L. Zapf · Journal of research of the National Bureau of Standards · 1954
A brief descript ion of the basic m ethod of testing alternating current watthoU!' m eters at the N ational Bureau of Standards is given, follo wed by a d escription of equipmeni.for a faster and less laborious m ethod.Equipment with several novel features has been a ssembled for making precise tests of alternating-current watthour meters by a comparison m ethod employing a group of carefully selected alternating-current watthour m eters, which serve as a secondary standard gr oup.One of t his group, d esignated the " St andard '\Vatthour M eter", is used with multirange instrument t ransfo rmers a s a r eference standard to test other watthour m eters with good precision.The testing procedure is explained, and t he formulas used in computing t he results of the tests a re d eri ved.An analy~i s of t he possible errors of m ea surem ent and data fr om numerous tests indicate that t he m easurement of energy applied to a watthour m eter under test can be relied upon to better t han 0.06 percent.