The evolution of the cathode spot distribution is an important aspect of the behavior of vacuum arcs controlled with an axial magnetic field.
The measurement of Partial Discharges (PD) in Gas Insulated Substation (GIS) enables to identify and analyse various types of defects that can result in electrical breakdown.
The density normalized Effective ionization coefficients and critical breakdown electric field of the Heptafluoro-iso-butyronitrile (Fluoronitriles), and Fluoronitriles-CO2 mixture are investigated using the steady state Townsend (SST) experimental setup, over a range of the density normalized critical electric field (E/N) from 200-1066 Td (E is the electric field and N the gas density).
A Gas Insulated Substation (GIS) consists of a high-voltage conductor maintained by spacers placed in a metal enclosure filled with a dielectric gas.
Phenomena of charge accumulation on the insulator surface are of major interest in Gas Insulated Substations (GIS) under Direct Current (DC)...
FastGrid is a project funding for an amount of 7.2 M€ by the European Union’s Horizon 2020. It started in January 2017 for a period of 42 months. Together 9 academic and 3 industrial partners participate to the development of a superconductive fault current limiter associated with a DC breaker will fulfil the requirement of one the protection strategies of the future HVDC networks. The project is divided in 4 technical main packages.
When a voltage is applied to a cable, electric charges are established in its electrodes, inducing an electric field in the dielectric. This electric field implies that the cable is submitted to an electrical stress which, under certain circumstances induces an accelerated ageing of its dielectric which may be followed by its breakdown.
SULPHUR hexafluoride, SF6, is the most common compressed gas used in high voltage power equipment since the 1950s and in HV transmissions and substations applications (GIS, GCB, GIL …), SF6 holds a prominent place because of its dielectric and chemical performance (high dielectric strength, non-toxicity, low condensation temperature, thermal stability, non-flammability, chemical inactivity with the other constituent materials of the apparatus, availability and moderate cost). It is one of the best insulators gas known today.
The design of reliable high voltage equipment remains a challenge nowadays. The surface charge accumulation at gas/solid interface is a major problem of HVDC GIS/GIL. The electric field can be distorted and the dielectric strength of the system can be thus reduced dramatically due to surface charges.
The development of HVDC networks leads to an increasing need of Gas Insulating Substations (HVDC-GIS). When an insulator is subjected to high thermoelectric dc DC stress, space charge accumulation can induce local increases of the electric field, which must be known and taken into account for the equipment design when the fields exceed several kV/mm.
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