Color Index of Transformer Oil: A Low-Cost Measurement Approach Using Ultraviolet-Blue Laser.

Area of Science:

• Electrical Engineering
• Analytical Chemistry
• Optical Physics

Background:

• Transformer oil color index (CI) is a critical indicator of oil quality and power transformer condition.
• Current ASTM D1500 standard methods rely on human observation, introducing subjectivity and limiting sample throughput.
• Limitations of traditional CI testing necessitate development of objective, automated, and efficient measurement techniques.

Purpose of the Study:

• To develop and validate a novel method for measuring transformer oil color index (CI) using ultraviolet-blue laser technology.
• To assess the accuracy and reliability of the laser-based method compared to standard CI determination.
• To explore the potential for commercialization of a portable, on-site device for transformer oil analysis.

Main Methods:

• Utilized ultraviolet-blue laser wavelengths of 405 nm and 450 nm to measure the CI of 20 transformer oil samples.
• Measured samples across a color index range of 0.5 to 7.5 at optical pathlengths of 10 mm and 1 mm.
• Developed a linear regression model to correlate laser measurements with CI, followed by validation with new oil samples.

Main Results:

• The laser-based method accurately quantified transformer oil CI with low root-mean-square errors (RMSEs) of 0.2229 (405 nm) and 0.4129 (450 nm).
• The developed linear regression model demonstrated high accuracy in predicting CI for new transformer oil batches.
• Measurements were precise across different optical pathlengths, indicating robustness of the technique.

Conclusions:

• The ultraviolet-blue laser method provides an accurate and objective alternative for transformer oil CI measurement.
• This technology holds significant potential for the development of low-cost, portable devices for on-site power transformer monitoring.
• Automation and objectivity of the laser method address limitations of current human-observer-dependent techniques.