The International Conference on Large Electric Systems (C. I. G. R. E.) [antikvár]

301 .-INFLUENCE OF A DISTORTING SYSTEM ON THE CONDITIONS GOVERNING THE MEASUREMENT OF POWER AND ACTIVE ENERGY (Report in the framework of Study Committee No. 16 dealing with reactive and distorting phenomena.) by I. S. ANTONIU, Kiigiiieei' E.S.E., Doctor of Technical Sciences, Professor at the Polytechnic Institute, Bucharest. SUMMARY Having assumed tltat ike distorting sysleiu is gaining importance on modern networks ivith the iyicreasing size of the networks it folloivs that a knowledge of the influence of this system on the conditions of poiver and active energy measurement is extremely necessary. The author makes a study of this influence on the more common instruments (electrodynamic xvattmeters and induction integrating meters) and in particular the error provided by such instruments both from the experimental and theoreticcd standpoint. The error is generally negative and the size of the error is fairly large. In conclusion, in view of the infinite number of distorting system.s which mag exist in electrical networks the author demonstrates that il is impossible to state a priori a method for adjusting power ami active energy meters intended for operating in such a system so as to bring the errors ivithin acceptable limits. Such insti'uments must be calibrated in place, in the distorting system in which they are intended io operate. On the other hand, the investigaiions on the influence exerted by the distorting system on the mea,mremeni of poiver and aciivc energy should be continued in order to acquire the greatest possible kno wledge for the purpose of indicaiing the engineering and administrative measures to be undertaken. HEPOKT 1. GENERAL Oiui oi' the engineering proJjiems set by the distorting system is tlie inlluence of this system of operation on the conditions governing the meastirement of power and active energy. The problem is extremely important having in mind that a modern network carries a large amount of distorting equipment of the first category (transformers, mutators) in addition to distorting equipment of the second category (buried cables, capacitances); hence, such a network represents a distorting system. The problem was included in the programme questionnaire of Study Committee No-. 16 dealing with reactive and distorting phenomena at the last meeting in Lausanne in October 1947 [1] The present study forms part of this programme. The measurement of A.C. active power is carried out almost exclusively by means of electrodynamic wattmeters. Induction wattmeters, which were widely employed some ten years ago particularly as panel instruments, are no longer used since in addition to the larger consumption than that required by electrodynamic instruments they also have the important fault that the readings are dependent on the network frequency [2]. Very small use is made of electromagnetic, electrostatic and thermal wattmeters. Active-energy measurements are carried out nowadays exclusively with induction meters which are both sinjple in construction and rol)ust. From the theoretical standpoint the operation of the instruments —l)oth wattmeters and integrating meters—should be as accurate in a distorting system as in a sinusoidal system. A series of experimental investigations [3] has shown that the situation is quite different in practice since the readings on these instruments show a fairly large discrepancy when measuring power or active energy. The aim of the present paper is to provide an explanation for the causes of measurement errors on these instruments in a distorting system and to indicate the order of magnitude of the errors. (') The figures in [] refer to the bibliography.