Charge Accumulation Dependence on Electric Field, Temperature, and Voltage Application Time in Polymeric Insulating Materials by Current-Integrated Charge Method
Hiroaki Uehara, Shinya Iwata, Ryota Kitani, Tatsuki Okamoto, Tatsuo Takada
Abstract
The current-integrated charge [ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}$ </tex-math></inline-formula> )] method used in this study can measure all fast-moving carrier charges and accumulated charges, which are shallow and deep trapped charges, respectively. The pulsed electroacoustic (PEA) method is an excellent method for observing the distribution of accumulated charges; however, it is difficult to measure fast-moving carrier charges using the PEA method. Currently, space charge measurement data on a wide range of electric field, temperature, and voltage application time are required. Therefore, this study aims to provide the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}$ </tex-math></inline-formula> ) data of charge accumulation characteristics by examining six types of polymeric insulating materials: low-density polyethylene (LDPE), cross-linked polyethylene (XLPE), polyethylene terephthalate (PET), polyimide (PI), polycarbonate (PC), and polyethylene naphthalate (PEN). The space charge accumulation is measured using the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}$ </tex-math></inline-formula> ) method. The <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}$ </tex-math></inline-formula> ) measurement results are obtained over a wide range of electric field (1–100 kV/mm), temperature (20 °C–80 °C), and voltage application time (0–5 h). The results show that the space charge accumulation characteristics [ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}$ </tex-math></inline-formula> ) data] of the six types of polymeric insulating materials are significantly dependent on these three factors. We believe that the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${Q}$ </tex-math></inline-formula> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">${t}$ </tex-math></inline-formula> ) method used in this study can contribute to further understanding of the charge accumulation properties of dc polymeric insulating materials.