Zhejiang dianli (May 2023)
Analysis of a light gas alarm triggered by a fault of an online monitoring device of the main transformer
Abstract
Online oil chromatography monitoring devices can be used for early warning of abnormalities in large oil-filled equipment. Therefore， they are now widely used in 110 kV and above transformers. Through principle analysis， test investigation， and simulation reproduction of the transformer body and the oil chromatography monitoring device in a light gas alarm of a 500 kV transformer， the reason of the defect is cleared up： the online oil chromatography monitoring device generates bubbles in the process of oil circulation due to a program error. The air is continuously injected into the transformer body during long-term operation and overflows to the gas relay when the oil is saturated， eventually leading to a light gas alarm. The causes of such defects are thoroughly analyzed， and corresponding suggestions on operation and maintenance are offered： the manufacturer of the online oil chromatography monitoring device should design a logic blocking to ensure that no abnormal gas generates； the operation and maintenance department should step up admittance testing， device calibration and regularly test the content of the air in the oil.
Keywords
