**Electrical Detection of Creeping Discharges over Insulator Surfaces in Atmospheric Gases Under AC Voltage Application**

#### **Michail Michelarakis 1,\*, Phillip Widger 1, Abderrahmane Beroual 2 and Abderrahmane (Manu) Haddad 1**


Received: 30 June 2019; Accepted: 30 July 2019; Published: 1 August 2019

**Abstract:** Creeping discharges over insulator surfaces have been related to the presence of triple junctions in compressed gas insulated systems. The performance of dielectric materials frequently utilised in gaseous insulating high voltage applications, stressed under triple junction conditions, has been an interesting topic approached through many different physical perspectives. Presented research outcomes have contributed to the understanding of the mechanisms behind the related phenomena, macroscopically and microscopically. This paper deals with the electrical detection of creeping discharges over disc-shaped insulator samples of different dielectric materials (polytetrafluoroethylene (PTFE), epoxy resin and silicone rubber) using atmospheric gases (dry air, N2 and CO2) as insulation medium in a point-plane electrode arrangemen<sup>t</sup> and under AC voltage application. The entire approach implementation is described in detail, from the initial numerical field simulations of the electrode configuration to the sensing and recording devices specifications and applications. The obtained results demonstrate the dependence of the generated discharge activity on the geometrical and material properties of the dielectric and the solid/atmospheric gas interface. The current work will be further extended as part of a future extensive research programme.

**Keywords:** creeping discharge; AC voltage; point-plane; atmospheric gases; flashover voltage; polytetrafluoroethylene (PTFE); epoxy resin; silicone rubber
