Abstract :
W. H. Pratt: Volt-ampere and volt-ampere-hour measurements seem to be occasioned almost wholly by the problem of making suitable rates for electrical energy when used at low power factor; that is of making rates that will stimulate the raising of the power factor in such cases. From this viewpoint devices of this kind should be in a measure self-eliminating, for once the power factor fairly approaches unity there is little or no excuse for the added complexity of apparatus above that of the watthour meter.
