Abstract :
The paper states that the introduction of an electricity tariff based in part upon a maximum apparent-power demand (VA m.d.), creates the need for a meter to measure apparent energy in a manner fair and just to all concerned. It gives two definitions for 3-phase apparent power and selects one as the more suitable basis for assessment of a maximum-demand charge. A brief description is given of a Merz demand mechanism, which registers maximum demand (m.d.) from integrations made over definite time intervals. Reference is made to the difficulties of integrating 3-phase apparent energy (VAh) and these difficulties are held to be primarily responsible for the introduction of alternative methods of m.d. charging. Some of the alternative methods are briefly compared with that of the maximum-apparent-power-demand charge, colloquially known as the kVA charge, in order to explain why so many attempts have been made to produce a true 3-phase apparent-energy meter. The paper recognizes that some very ingenious meters have already been designed but suggests that none is entirely satisfactory for industrial applications. It shows how recent developments have made possible the introduction of a new type of apparent-energy meter based on an entirely new principle. A description is given of a new type of volt-ampere indicating instrument, and this provides an introduction to a treatise on the new apparent-energy meter, whose main components are a dry plate rectifier, a transductor and an induction-type integrating meter. A bibliography is included to indicate the background of knowledge and opinions which influenced the development of the meter. Appendices deal with the interpretations of 3-phase volt-amperes, the voltage representation of a 3-phase system, and¿with the aid of oscillographs¿describe the operation of the meter components.
