Accelerated Charge Dissipation by Gas-Phase Fluorination on Nomex Paper

Abstract

The surface charge and space charge accumulation in paper used in oil-paper insulation system may distort electric field distribution and lead to the flashover and breakdown of insulation system. In this paper, the effect of gas-phase fluorination on the surface charge and space charge characteristics of oil-impregnated Nomex paper was investigated. Nomex T410 was fluorinated at 25 • C using F 2 /N 2 mixtures with 20% F 2 in volume at 0.05 MPa for 15, 30 and 45 min. Fourier Transform Infrared Spectroscopy (FTIR) proved that the molecular chain scission and cleavage occurred during gas-phase fluorination. Furthermore, the surface charge and space charge characteristic of the original and fluorinated oil-impregnated paper were measured using an electrostatic voltmeter and Pulsed Electroacoustic (PEA) equipment respectively. Furthermore, the hole and electron trap distribution of the samples were obtained by Isothermal Surface Potential Decay (ISPD) model. The results showed that both the positive and negative charge decay rates were accelerated by gas-phase fluorination and the hole, electron trap energy and density of the fluorinated samples were reduced by fluorination. It is suggested that the space charge dissipation was also accelerated by fluorination, indicating that gas-phase fluorination is an effective approach to modify the charge dynamics of oil-impregnated Nomex paper.

Self-Assembled NBR/Nomex Nanofibers as Lightweight Rubbery Nonwovens for Hindering Delamination in Epoxy CFRPs

“…In fact, signals typical of both NBR and Nomex are still present, such as the nitrile stretching at 2237 cm –1 for NBR 37 , 38 and the amide carbonyl stretching at 1643 cm –1 and aromatic C=C stretching at 1603 and 1529 cm –1 for Nomex. 39 , 40 Such evidence confirms that the nanofiber is composed of an NBR-rich phase that can be removed by chloroform washings, leaving the morphologies reported in Figure 2 . However, the resulting fibril-like and quasi-core–shell structures are also made by an NBR-Nomex blend that does not completely release the rubber during washings.…”

Surface Degradation of Oil-Immersed Nomex Paper Caused by Partial Discharge of High-Frequency Voltage

“…As a result, the backbone of the benzene ring structure for aramid molecular is broken, which causes the molecular weight of the aramid molecular to decrease, affecting the mechanical properties of the oil-impregnated Nomex paper. [22][23][24][25] Figure 8 shows the content of carbon and oxygen in oilimpregnated Nomex paper based on EDS. It can be seen that the atomic and mass percentage of carbon are the lowest and the atomic and mass percentage of oxygen are the highest for the blank sample.…”

“…It can also be observed that the position and shape of the diffraction peaks before and after PD degradation remain basically unchanged, and that only the intensity of the diffraction peak changes. In order to further analyze the influence of high frequency on the aggregation structure of oil-paper insulation, the integral method [23][24][25] has been used to calculate the crystallinity of the paper, as shown in Table II. The corresponding calculation formula is expressed as:…”