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Effect of surface wetting behaviour on discharges from water drops in electric fields
Corona is a partial discharge that is observed on High Voltage overhead lines and water drops play significant role in the enhancement of this phenomenon.In this work we investigate the effect of the surface wetting behavior on the onset of corona formation from sessile or impacting water drops
Keywords: corona, partial discharge, hydrophobicity, superhydrophobicity, drop impact, sessile drop
High Voltage overhead lines are currently an integral part of the electrical energy transport system. A
key aspect of their environmental performance is related to the so-called corona effects. Corona is a partial
electric discharge caused by high electric fields on the conductor surface and is the cause of noise, radio
interference and, in the case of High Voltage Direct Current (HVDC), also ion currents at ground level. Water
drops are one of the primary determinant of how intensive these effects are. By tailoring the wetting behaviour of
a surface the deformation of a drop due to the effect of an electric field can be controlled. Drops on a hydrophilic
surface under the effect of an electric field can reach a Taylor cone that generates a partial discharge that
may lead to a breakdown (see panel a).On the other hand drops on a surface with extreme water repellency
(superhydrophobic surface, see lower panel) may lift-off inside an electric field without any corona discharges
(see panel b). However, a drop that impacts a superhydrophobic surface (see panel c), a process similar to
rainfall, exhibits a different behaviour since its shape deformation and the resulting local intensification of the
electric field finally leads to a partial discharge inception (see panel d). Therefore, the surface wetting behaviour
of a conductor is extremely important for the manipulation of partial discharges.
High Voltage overhead lines are currently an integral part of the electrical energy transport system. A key aspect of their environmental performance is related to the so-called corona effects. Corona is a partial electric discharge caused by high electric fields on the conductor surface and is the cause of noise, radio interference and, in the case of High Voltage Direct Current (HVDC), also ion currents at ground level. Water drops are one of the primary determinant of how intensive these effects are. By tailoring the wetting behaviour of a surface the deformation of a drop due to the effect of an electric field can be controlled. Drops on a hydrophilic surface under the effect of an electric field can reach a Taylor cone that generates a partial discharge that may lead to a breakdown (see panel a).On the other hand drops on a surface with extreme water repellency (superhydrophobic surface, see lower panel) may lift-off inside an electric field without any corona discharges (see panel b). However, a drop that impacts a superhydrophobic surface (see panel c), a process similar to rainfall, exhibits a different behaviour since its shape deformation and the resulting local intensification of the electric field finally leads to a partial discharge inception (see panel d). Therefore, the surface wetting behaviour of a conductor is extremely important for the manipulation of partial discharges.
We aim to employ fundamentals in wettability engineering and materials science to fabricate surfaces
with different wettabilities. In this line experiments will be conducted to evaluate the interaction between static
or impacting water drops and fabricated surfaces under the effect of high voltage electric fields. We also aim to
determine whether there is a strong correlation between surface wettability and partial discharge generation.
The student will have the chance to join a multidisciplinary team and work within an exciting and interesting
project that combines aspects of different disciplines.
Type, Theory: 20%, Experiments: 80%
We aim to employ fundamentals in wettability engineering and materials science to fabricate surfaces with different wettabilities. In this line experiments will be conducted to evaluate the interaction between static or impacting water drops and fabricated surfaces under the effect of high voltage electric fields. We also aim to determine whether there is a strong correlation between surface wettability and partial discharge generation. The student will have the chance to join a multidisciplinary team and work within an exciting and interesting project that combines aspects of different disciplines. Type, Theory: 20%, Experiments: 80%
Christos Stamatopoulos, High Voltage Laboratory, ETH, Zurich
Office: ETL H31.1
Email: stamatoc@ethz.ch
Tel: +41 44 632 2975
Christos Stamatopoulos, High Voltage Laboratory, ETH, Zurich Office: ETL H31.1 Email: stamatoc@ethz.ch Tel: +41 44 632 2975