Real-Time Transformer Oil Polychlorinated Biphenyl Sensor

Polychlorinated biphenyls (PCBs) remain a significant environmental threat even though manufacturing of PCBs was discontinued 30 years ago. Due to the chemical and thermal stability of PCBs in the environment and the continued use of transformers containing these chemicals, very specific regulations are in place that require quantification of PCBs in all transformer oil. The Toxic Substance Control Act has mandated that the concentration of PCBs in transformer oil be less than 50 parts per million. Analysis of PCB concentration is currently performed by SW-846 Method 8082 standard method in an analytical laboratory using gas chromatography. This type of analysis is time consuming and costly. In addition, for this offsite analysis, oil must be removed from the transformer that potentially exposes workers and the environment to PCBs. Eltron is developing a new portable real-time sensor that can be used onsite to not only quantify the PCBs that are present but also to determine PCB concentration. In the EPA Phase I SBIR project, Raman Spectroscopy and multivariate analysis were combined to create a rapid in situ sensor capable of a simultaneous detection of PCB concentration and composition within transformer oil. Regression models were prepared that could detect PCB concentrations as low as 5 ppm, and classification models were prepared that could predict the type of Aroclor present in transformer oil. During the Phase II project, sensor sensitivity will be improved by testing all major transformer oil types and accounting for appropriate interferences. Surface Enhanced Raman Spectroscopy will be used to lower the sensor detection limit. Finally, a prototype instrument including user friendly software will be prepared for field testing. The final product of this project will be a real-time sensor that is cost effective, portable, user friendly, and most importantly will prevent the hazardous removal and transportation of contaminated transformer oil for PCB analysis. The expected instrument capital cost is equivalent to current GC costs ($30K); however, the per sample testing cost will be significantly less than GC methods. This type of hand-held sensor will find extensive use by electric utilities (Sacramento Municipal Utility District) and hand-held Raman instrument manufacturers (Raman Systems, Inc.). An expected global market of $119 M is expected for this type of instrument by 2009.