Detection And Analysis For CO And CO₂ Dissolved In Transformer Oil Based On TDLAS

The performance of low overheating is one of the early failure of transformer,CO and CO₂ content change greatly while content of hydrocarbon gas generated from the decomposition of the oil is low.Therefore con tent and gas production rate of CO and CO₂ are often used to diagnose solid insulation aging of transformers.Meanwhile CO and CO₂ dissolved in transformers often associated with the analysis of furfural to diagnose insulation aging,low temperature overhe ating fault.Optical detection method has advantages of anti-electromagnetic interference,non-contact measurement,etc.However,there are still some problems to be solved as to existed optical dissolved gas analysis method: multiple cross-sensitivity and subject to vibration noise.In order to overcome the shortages,novel optical technologies of TDLAS was used for oil dissolved CO and CO₂ monitoring.In this paper,the existing on-line monitoring technology of dissolved gases in oil is analyzed and summarized as well as the basic principle of tunable diode laser absorption spectroscopy.Wherein,the selection of central wavelength for CO and CO₂ is critical.The CO and CO₂ system is designed and built in the laborary.The DFB laser with metal gratting was chosed for spectral resolution.The system is with features of short separation time,simple operating procedures,no carrier gas.In the system,multi-gas cross-sensitivity is overcome and sensitivity at ?L/L level is achieved.For application of the dissolved CO and CO₂ on-line monitoring system,the topological structure of the system is designed,which mainly includes oil-gas separation module,optical sensor module,data analysis module and communication module.The oil-gas separation module contain circulating pumps,vacuum pumps and solenoid valves.The software is designed which provides the friendly man-machine connection contact surface,users can easily configure the system operating parameters according to their requirements.