Les Renardieres Research Articles

Computer Aided Design of Synthetic Test Circuits for High Voltage Circuit-Breakers

Developments in electrical power transmission systems require the use of circuit-breakers with increasing breaking capacity. To test these equipments, direct testing is no longer feasible. This means that synthetic tests are necessary. These tests require circuits with a response specified by ANSI, IEC, ..., standards. Specific software has been created to permit automatic synthesis and optimum design of these circuits. This tool is used at the High Power Test Laboratories LEP of Electricite de France at Les Renardieres. In the paper, three different high voltage circuits are considered (fig. 1, 2, 3). They enable to provide ANSI and IEC (2, 4-parameter) transient recovery voltages (TRV). In view of the method by which the standards define the parameters of the transient recovery voltage it is quite impossible to analytically link these parameters with the value of the components of the test circuit. A digital computation is necessary to determine the parameters of the TRV corresponding to a given test circuit. Laplace transformation is used to determine the response of the circuit. Moreover an iterative process is required to establish the synthesis of the proposed circuit. Iterative formulae, which make the process converge at a satisfactory speed, have been developed. As a general rule, with the usual shapes of TRV and requiring an accuracy of 1 % on the parameters, the solution is obtained after approximately twenty iterations, taking 30 seconds on a HP 1000 computer.

Digital Acquisition and Numerical Processing of Measuring Signals, in a High Voltage Circuit Breaker Testing Laboratory

This paper presents the data acquisition system used at the High Power Test Laboratory at les Renardieres (EDF - France) since the beginning of 1984. The hardware configuration is first described. The main problems are underlined in order to justify the choice of the adopted system. Then the major outlines of the developed softwares (and the encountered difficulties) are presented. An example, relative to a 245 kV circuit breaker terminal fault shows the results given by the digital system. The acquired experience proves that automatic analysis of signals permits to satisfy speed and accuracy criteria.

Contribution to a Better Understanding of Impulse Voltage Measuring Systems

In a indoor U. H. V. laboratory, the parameters governing the knowledge of a given high impulse voltage phenomena are emphasized by the geometrical size of the circuit and must therefore be carefully studied. The way "Les Renardieres" U. H. V. laboratory has endeavoured to have a better knowledge of its impulse measuring systems is presented and discussed.

Predetermination of the Radio Noise Level Under Rain of an Extra-High-Voltage Line

Radio noise levels under rain of 4-conductor bundles installed at les Renardieres experimental station have remained remarkably constant during the first two years of operation. These levels are reached as soon as the rain intensity exceeds 0.01 mm /min. It is therefore possible to predetermine accurately the radio noise level under rain of a line equipped with 4-conductor bundles depending on the surface gradient and the radius of the subconductors.