UNDERSTANDING COMBUSTIBLE GASES IN TRANSFORMERS, LTCS, AND OCBS
This month’s Featured Technical Paper is from the Proceedings of the 2026 International Conference of Doble Clients. The paper is titled: Understanding Combustible Gases in Transformers, LTCS, and OCBS.
Abstract
Combustible gases generated from thermal and electrical incipient faults can accumulate in the headspace of liquid-filled electrical equipment, including transformers, on-load tap changers (OLTCs), and oil circuit breakers (OCBs). While gas accumulation is a common occurrence that has been managed for over a century, certain conditions can result in combustible gas concentrations exceeding the Lower Explosive Limit (LEL), creating potential hazards to both equipment and personnel. This paper examines the fundamental principles governing combustible gas behavior in electrical equipment, including gas partitioning, Ostwald solubility coefficients, and the fire triangle concept. Through detailed analysis of various operational scenarios and the interaction between fuel, oxygen, and ignition sources, this work provides practical guidance for assessing flammability risks and implementing appropriate safety measures. The paper includes comprehensive tables of LEL/UEL values, solubility coefficients for various insulating liquids, and oxygen requirements for combustion support, offering utility operators and maintenance personnel essential tools for risk assessment and decision-making.
Doble Service Agreement Clients
This and other technical papers and presentations are available in the MyDoble Resource Center - one of the many benefits available to you as a Doble Service Agreement Client. To get to the MyDoble Resource Center login click here. Not a member? Follow the sign-up process.