Optimization of Ethanol Detection by Automatic Headspace Method for Cellulose Insulation Aging of Oil-immersed Transformers

Abstract

The method using ethanol to evaluate the cellulose insulation aging condition of oil-immersed transformers has been proposed. At present, the dominating method for detecting ethanol in insulating oil is to use headspace–gas-chromatography–mass-spectrometry (HS-GC-MS). However, the problem of quantitative inaccuracy will be sometimes encountered in the actual detection process due to improper instrument parameter setting and improper manual operation. In this study, as an aging marker, ethanol in transformer insulating oil was separated by using VF-624 ms capillary column. The effects of gas-chromatography–mass-spectrometry (GC-MS) optimization conditions, headspace equilibrium temperature, headspace equilibrium time and standard solution preparation method on the determination of ethanol content in oil were discussed, and optimized measures were proposed. The experimental results showed that the measurement can be more accurate under the headspace temperature of 80 °C and the headspace time of 40 min, and relative standard deviation percentage (RSD%) could reach to 4.62% under this condition. It was also pointed out that, for the preparation of standard solution, the method which controlled the sampling volume of anhydrous ethanol by microliter syringe could make the peak area of ethanol chromatogram have a better linear relationship with the standard curve. Under the similar linear range, the goodness of fitting curve without diluting process could be as high as 0.9993, while the method of preparing the stock solution and diluting stepwise to obtain the fitting curve only had a goodness of 0.9910. The method was validated by standard addition recovery test, and the recovery values obtained were between 90.3% and 95.8%. The optimized method is of great significance for the measurement of ethanol dissolved in insulating oil.

Monitoring of alcohol-based hand rubs in SARS-CoV-2 prevention by HS-GC/MS and electrochemical biosensor: A survey of commercial samples

“…Headspace GC is a routinely used technique to investigate volatile analytes even though alcohols determination in several matrices may be carried out also using GC with direct sample injection [16] , [20] . However, headspace analysis is particularly appropriate for ABHRs considering their formulations, since GC parts fouling is reduced and cleaner extracts are obtained ( Figure SI1 ) than with direct sample injection [24] .…”

“…The simultaneous determination of EtOH, IPA, n-PA as active ingredients in hand sanitisers and of MeOH as impurity ruled by the Cosmetic Products Regulation [23] , was investigated with a specific analytical method. Considering that the target compounds are volatile, HS-GC/MS was chosen for the analysis of hand sanitisers because it reduces the equipment contamination caused by other ingredients [24] . The headspace conditions (as equilibration temperature and equilibration time) and acidification sample treatment were studied and optimised.…”

A review on a novel method for aging evaluation of transformer insulating paper based on methanol

“…Methanol is a very promising characteristic product reflecting the aging states of transformer insulating paper [48,49]. At present, the research on the aging evaluation of transformer oil paper insulation based on methanol is in the initial stage [50,51], the mainstream methods for detecting methanol content include gas chromatography (GC-FID) [52], spectroscopy [53], gas mass spectrometry (GC-MS) [47,54], etc. Each method has certain advantages, but also has limitations.…”

Gas-Sensing Properties of Dissolved Gases in Insulating Material Adsorbed on SnO2–GeSe Monolayer

“…Therefore, identifying the early latent fault of the transformer is a key problem to be solved for the power industry. Currently, oil-immersed transformers are commonly used in power systems [4][5][6][7]. An oil-immersed transformer in the long-term operation process can incur an electrical fault or thermal fault.…”