LED lighting uses typically switched mode power supply (SMPS) techniques to generate the appropriate LED voltage and current out of high mains voltages. A variety of SMPS controllers is available on the market for this application. Most of these cont…

In order to replace the lightning impulse test, a very sensitive PD-measurement is required for onsite tests of GIS (CIGRE Joint Working Group 33/23.12 in Electra No 176, 1998). The most sensitive UHF-PD-measurement technique consists of low-noise hi…

The distribution system operator TIWAG-Netz AG operates a 220 kV grid in the alpine region of Tirol. Due to the age of the conductors, the fittings and the pylons (approximately 50 years), the question has arisen as to whether, for parts of…

In February and March 2008 cyclone “Emma” crossed some countries of central Europe and caused severe damages. In very local areas thunderstorms with downbursts were embedded in “Emma” and led to collapses of overhead lines.Downbursts are downward win…

In the last few years, the demand for testing extra-long cables, such as submarine cables has grown rapidly. The existing testing methods have been complemented by a new testing technology called DRT (Differential Resonance Technology). This testing …

To improve personal safety and reduce the environmental impact of electrical power supply, alternative insulation fluids are demanded for large power transformers. With their biodegradability, the fact that they can be produced from renewable resourc…

Dielectric response analysis is an advanced technique, providing information about the insulation condition of the measured test object. It is typically used for power transformers, where the water content in the solid cellulosic insulation can be as…

Due to the high magnetic conductivity of transformer cores, very small direct currents in the electric power grid are sufficient to cause half-cycle saturation of the core. Even minor DC-bias leads to a considerable increase of the noise level and to…

A key and important aspect of future power and energy systems is the integration of renewable and distributed energy resources. In order to develop, test and implement such distributed energy resources appropriate methods, procedures and guidelines a…

The generation of white light by Light Emitting Diodes (LED) is presented. Unlike thermal emitters (e.g. incandescent bulbs) or UV excited fluorescent light-sources (e.g. compact fluorescent bulbs), the emission is in the visible range only, allowing…

A short overview on thermal management solutions for LED systems is presented. Heat transfer modes of these systems are described, from junction to ambient, giving an estimate on the contribution of each process involved, focusing on the key paramete…

LED-Beleuchtungsmittel sind aufgrund ihrer Effizienz und Leistungsfähigkeit bereits am Markt etabliert und stellen am Beleuchtungssektor enormes Potential für Energieeinsparung und zusätzlicher vorteilhafter Merkmale für den Konsumenten dar. Aufgrund…

The nature and quality of artificial lighting are becoming more and more recognized and debated issues concerning their impact on comfort, well-being and even human’s health (chronobiology). Therefore, the target must be to emulate natural (sun) ligh…

Color temperature constancy and color maintenance are key issues in the context of the utilization of light-emitting diodes (LEDs) for general lighting applications. For a systematic approach to improve the white light quality of phosphor converted L…

Innovationen haben zwei Dimensionen: Die erste Dimension ist markt- bzw. anwendungsgetrieben. Hierzu zählen neue Funktionalitäten, die verschiedene Arbeits- und Lebensbereiche beeinflussen, aber auch neuartige Produkte, die aus Projekten resultieren.