Understanding Trap Effects on Electrical Treeing Phenomena in EPDM/POSS Composites

Abstract

POSS (polyhedral oligomeric silsesquioxane) provides an interesting alternative nano-silica and has the potential of superior dielectric properties to restrain electrical degradation. By incorporating POSS into EPDM to suppress electrical tree, one of precursors to dielectric failure, is promising to improve the lifetime of insulation materials. This paper focuses on the electrical treeing phenomena in EPDM/OVPOSS (ethylene propylene diene monomer/octavinyl-POSS) composites based on their physicochemical properties and trap distributions. ATR-IR and SEM characteristics are investigated to observe the chemical structure and physical dispersion of EPDM/OVPOSS composites. Electrical treeing characteristics are studied by the needle-plane electrode, and the trap level distributions are characterized by surface potential decay (SPD) tests. The results show that the 3 wt% EPDM/OVPOSS is more effective to restrain the electrical tree growth than the neat EPDM in this paper. It is indicated that the EPDM/OVPOSS with a filler content of 3 wt% introduces the largest energy level and trap density of deep trapped charges, which suppress the transportation of charge carriers injected from the needle tip and further prevent the degradation of polymer molecules. The polarity effects are obvious during the electrical treeing process, which is dependent on the trap level differences between positive and negative voltage.

Silica Surface-Modification for Tailoring the Charge Trapping Properties of PP/POE Based Dielectric Nanocomposites for HVDC Cable Application

“…Therefore, the silicas modified with polar silanes introduce deeper traps into the nanocomposites. This phenomenon is also described in literature, where studies or models indicate that polar groups or hetero-atoms of electronegativity higher than the one of carbon can introduce deep traps [11], [40]- [42]. It is worth to note that the most pronounced one is the silica modified with NCO and amino silanes, which both contain a nitrogen atom.…”

“…However, if the silica was modified with a silane containing only one alkoxy group, there are still unreacted silanol or siloxane groups exposed on the silica surface ( Fig.19 (c)). This inefficient shielding will influence the final interface properties between the silica and a polymer matrix [40]. As a result, the silica modified with TMES, VDMES or PDMES have still unreacted silanol or siloxane group exposed to the Polymer matrix.…”

Effect of Polycyclic Compounds Fillers on Electrical Treeing Characteristics in XLPE with DC-Impulse Voltage

“…After the addition of the polycyclic compound, the trap depth and density of samples increase significantly. The traps enhance the charge trapping ability of the needle tip and easily forms the same polarity charge accumulation to weaken the external electric field, resulting in a decrease in the injected charge amount [41]. At the same time, with the deep trap level and the trap density increasing, the internal charge trapping of the sample enhances, resulting in a decrease in the internal free charge of the sample.…”

“…The free charge may be captured by the local state (trap) during the extended state migration process. The charge transfer and exchange process between the extended state and the local state affects the migration characteristics of carriers [41]. After the addition of the polycyclic compound, the carrier mobility is reduced, and the carrier mobility of XLPE-A is the smallest.…”

Rogowski coil sensor in the digitization process to detect partial discharge

“…Even with an increase in the frequency of PD can cause excessive heat, which results in increased destruction activity that occurs in propagation that forms a tree (treeing) like a conductor containing an electric charge due to PD to one of the more intense conductors. Treeing increases the strength of the electric field significantly, failing insulation [1][2][3]. Catastrophic insulation must be overcome if the detection of PD periodically to be detected early symptoms of aging insulation.…”