This study addresses the effect of nanoparticles’ conductivity and surface charge on the dielectric performance of insulating nanofluids. Dispersions of alumina and silicon carbide nanoparticles of similar size (~50 nm) and concentration (0.004% w/w) were prepared in natural ester oil. The stability of the dispersions was explored by dynamic light scattering. AC, positive and negative lightning impulse breakdown voltage, as well as partial discharge inception voltage of the nanofluid samples were measured and compared with the respective properties of the base oil. The obtained results indicate that the addition of SiC nanoparticles can lead to an increase in AC breakdown voltage and also enhance the resistance of the liquid to the appearance of partial discharge. On the other hand, the induction of positive charge from the Al₂O₃ nanoparticles could be the main factor leading to an improved positive Lightning Impulse Breakdown Voltage and worse performance at negative polarity.

Scope of the current study is to examine the electrical characteristics of photovoltaic (PV) modules after being subjected to high impulse voltages, which are usually generated by lightning or switching surges. Tests were conducted at the High Voltage Laboratory of the University of Patras in Greece on PV modules of 5 and 195 W _p derived from different manufacturers, by performing various stress scenarios. The I‐V and P‐V characteristic curves of the examined modules, before and after the impulse voltage stress tests, are compared with each other considering the modules' ability to maintain their nominal electrical characteristics. After certain periods of time, the electrical performances of the stressed modules are examined again in order to ensure whether they regain some or all of their properties in case of prior differentiation. The experimental results are compared with theoretical estimations, so as to confirm the rightness of the presented procedure.

In this paper, data analysis concerning human and animal deaths and injuries from lightning in Greece, is presented, for a time period of eleven years, from 2000 to 2010. In addition lightning strikes in factory facilities, buildings, aircrafts and lightning-ignited fires are recorded and presented. Lightning death data have been distributed in years and months of occurrence, and an effort has been paid to connect the casualties with the places they occurred and the actions of the victims. Furthermore in this paper, the relative lightning death indicator Dr is calculated for different, places in Greece to express the relative number of lightning deaths in a country (or province) taking into account its population, its area and the lightning activity Ng. This indicator is useful for comparison purposes and could merely be a criterion for the effectiveness of lightning protection measures, and for the results of educational and informational campaigns about protection from lightning danger.

In this paper is presented the performance of metal-oxide surge arresters, during fast transients. The simulations were carried out with the EMTP-ATP program. The equivalent circuits were those proposed by the IEEE and Pinceti-Giannettoni. The residual voltages of various rated voltages lightning arresters and for lightning currents with different peak values and front times were estimated. The results also been compared with the manufacturer's data.

The purpose of this study is to determine the dielectric strength of a photovoltaic module through laboratory measurements. The measurements were taken using the standard impulse voltage, according to IEC 61730-2. Measurements were taken before and after the voltage stress in order to investigate in which way the module is affected. These results appear in the IV and PI characteristic curves. Subsequently, after a period of six months, the stressed module was compared to a similar non-stressed to find out whether the first regains some of its properties. In the same way the IV and PI curves are quoted. In conclusion the results obtained are evaluated and confirmed by the standards with a view to approach an optimal design of lightning and surge protection systems for photovoltaic installations (PVIs).