New insulating gases for gas-insulated metal enclosed switchgear

For many decades sulfur-hexafluoride (SF6) has been used as insulating gas with good arc-extinction properties in gas-insulated metal-enclosed switchgear (GIS) and circuit breakers. Presently, the high global warming potential (GWP) of SF6 is motivating a worldwide search for environmentally friendly alternatives. Promising alternative gases with dielectric properties comparable to SF6 have a high dew point, and can be used in GIS as gas mixtures together with carrier gases only. As a precondition for their practical use, characteristic properties of alternative gases and their mixtures have to be examined. The focus of the research project with the new insulating gases is on the insulating capacity of different electrode arrangements with different gas mixtures relevant for high voltage application, the influence of gas liquefaction and the modeling of discharge development.

For further information, please contact: Michael Peiß, M.Sc.

Hybrid insulation concepts with environmentally friendly insulating gases

In existing gas-insulated switchgear, sulfur hexafluoride is the predominant insulating medium. In the foreseeable future, however, this powerful greenhouse gas is to be replaced by an environmentally friendly alternative, such as synthetic air. For the optimization of the insulation capabilities of air-insulated switchgear, hybrid insulation concepts by coating with dielectric solids of different coating thicknesses are a promising approach. In this context, the starting points are investigations on the capacitive control of the electric field as well as influences of various surface properties. Basic investigations of solid materials and properties as well as discharge mechanisms in synthetic air are the subject of this research project. Within the scope of these activities, the application potential for gas-insulated switchgear of the high voltage level up to 420 kV is evaluated.

For further information please contact: Patrick Gambeck M.Sc., Maximilian Millisterfer M.Sc.

Gas-insulated AC disconnectors and earthing switches

Disconnectors provide visible galvanic insulation of electrical units and networks when open. In addition, they are capable of switching smaller currents that occur when connecting or disconnecting electrical system components. They are also able to control large currents during commutation processes, as long as no significant change in voltage occurs. Earthing switches are used for earthing and short-circuiting plant components. They are not required to carry continuous operating currents, but must withstand short circuits for a defined time. The replacement of sulfur hexafluoride as an insulating gas with alternative insulating gases such as synthetic air creates new challenges for the use of gas-insulated disconnecting and grounding switches. Switching operations under various conditions, as well as concepts to increase switching performance, are investigated.

For further information please contact: Felix Kaiser M.Sc.