Die Einhaltung der gesetzlichen Abstrahlungsgrenzwerte z.B. nach EN55011 fur ISM Gerate oder CISPR 25 fur Automobilkomponenten wird oft erst am Ende der Gerateentwicklung auf einem Freifeld oder in einer Absorberkammer uberpruft. Dabei wird eine integrale Messung des gesamten Systems durchgefuhrt, wobei die Zuordnung auf lokale Schwachpunkte des Elektroniksystems in der Regel nicht moglich ist. Dafur kommen so genannte Schnuffelantennen zum Einsatz. Damit ist eine Ortung der Schwachstellen moglich. Auserdem bietet sich an, wahrend der Entwicklungsphase gezielte EMV-Messungen und -Optimierungen durchzufuhren. Dafur haben sich kleine Monopolund Rahmenantennen etabliert. Aufgrund der unterschiedlichen Empfangscharakteristiken wird je nach Anwendung eine geeignete Sonde ausgewahlt. Speziell bei der Qualifikation von Automobilkomponenten sind teilweise Empfindlichkeiten erforderlich, die mit den herkommlichen Sensoren nicht erreicht werden, z.B. wenn sich ein Elektronikmodul direkt bei der Scheibenantenne befindet. Fur den Fall, dass die Elektronik in einem metallischen Schirmgehause untergebracht ist, wird ein Sensor mit hoher Empfindlichkeit vorgestellt, der den bestehenden Satz der Nahfeldsonden erganzt.

Generator step-up transformers belong to the central elements of a power plant, since they are the connection between the electricity generator and the power grid. A huge amount of the German power stations have been erected during the 7 ties . Therefore, today the generator transformers in these power stations have reached an age of 30 years and above. Due to a number of reasons, the power stations available today must be operated during the next years. This leads to the question when is it technically and economically reasonable to exchange a generator transformer, especially if the remaining operating time is limited. Investigations of insulation material taken from a generator transformer presented in this paper show that this generator transformer has reached the end of its lifetime according to the state-of-the-art in transformer engineering. Results of the dissolved gas analysis (DGA) and analysis of the furanic compounds in the oil are also discussed in this report.

Modern impedance analyzers offer the possibility to measure the frequency related conductivity and the complex permittivity epsiv(omega) of a sample from a few mHz up to some MHz. Impedance measurements are relatively easy to accomplish and deliver very precise results over a wide range of conductivity and capacitance. Using the measured spectra from oil-paper-confining-layer, inference can as well be made on the mobility of ions & molecules and also regarding the transport-mechanisms. It could be proved that impedance measurements with dry and moist oil-paper-confining-layer-systems show a distinctive permittivity function epsiv(omega). For modelling the dielectric performance of pure oil and pure paper systems the cole-cole-function approach for dielectric systems was applied. The modification of the relative permittivity is on one hand caused by polarization processes within the confining-layer-system and on the other hand by lamination on the boundaries between oil and paper. The moisture and temperature have a great impact on the results. One reason is the high relative permittivity of water, the other the heat convection which disturbs the lamination and the polarization. This paper supplements the theoretical model with experimentally measured data permitting better understanding of complex processes in insulation systems. The model of oil-paper insulation layers in the frequency domain could be used for transformers diagnosis