Effect of carbon black type and concentration on the performance of semiconductive shielding material of high‐voltage cable

Abstract

Semiconductive shielding layer as an important part of high‐voltage cable, its performance directly affects the safe operation and the service life of the cable. Carbon black (CB) is the main conductive filler of shielding materials, and its type and concentration directly affect the performance of the shielding layer. In this paper, CB‐A with higher structure and CB‐B with lower structure were used as conductive fillers and EBA was chosen as the matrix resin to prepare the shielding materials. The CB concentrations of the shielding materials were 35, 45, and 55 phr. The influences of CB type and concentration on the physicochemical, electrical, thermal and mechanical properties of the shielding materials were investigated. The research shows that when the CB types are the same, the higher the concentration of CB, the more intensive the CB network in the shielding material, and the more serious the CB agglomeration phenomenon. With increasing CB concentration, shielding materials show a decreasing trend of volume resistivity, an increasing trend of thermal conductivity, and a decreasing trend of mechanical properties. When the CB concentration is the equal, the CB‐A has better dispersion in the matrix resin, CB‐A/EBA shielding material has lower volume resistivity and weaker PTC effect, CB‐A/EBA shielding material has higher thermal conductivity at low temperature and CB‐B/EBA shielding material has higher thermal conductivity at high temperature, CB‐A/EBA shielding material has better mechanical properties. A comprehensive comparison shows that CB‐A/EBA shielding material with a concentration of 45 phr has excellent overall performance, with volume resistivity of 15.3 and 68 Ω·cm at 25°C and 90°C, respectively. The thermal conductivity is 0.434 W/(m K) at room temperature and 0.536 W/(m K) at 90°C. The stress is 31.08 MPa and the strain is 570.2%. This work has important reference for the selection of conductive fillers and performance improvement of semiconductive shielding materials.

Effect and mechanism analysis of matrix resin type on thermal aging characteristics of semi‐conductive shielding material for high voltage cable

“…16,17 The semiconductive shield layer is located between the conductive core and the insulating layer, which plays an important role in the cable to uniform the electric field and reduce the interfacial air gap. [18][19][20] The main components of the semi-conductive shielding material are conductive carbon black and matrix resin. Carbon black is formed by the incomplete combustion of organic matter at high temperature above 500 C, and basically does not age at 135 C. Therefore, under the influence of long-term working temperature, the temperature mainly affects the performance of the matrix resin in the shielding material, but the conductive filler carbon black has little influence.…”

“…The research shows that the safety of high‐voltage cable is not only related to the insulation layer, but also closely related to the inner semi‐conductive shielding layer (referred to as: shielding layer) 16,17 . The semi‐conductive shield layer is located between the conductive core and the insulating layer, which plays an important role in the cable to uniform the electric field and reduce the interfacial air gap 18–20 . The main components of the semi‐conductive shielding material are conductive carbon black and matrix resin.…”