Electrochemical sensor for predicting transformer overload by phenol measurement

Area of Science:

• Electrochemistry
• Biotechnology
• Power Systems Engineering

Background:

• Transformer overload poses significant safety and economic risks to the power transmission industry.
• Phenol levels in transformer oil indicate overload risk due to the degradation of phenol-formaldehyde resins.
• Accurate and timely phenol measurement is crucial for preventing transformer failures.

Purpose of the Study:

• To develop and evaluate novel polyphenol oxidase (PPO) based sensors for measuring phenol in transformer oil.
• To assess the performance of two sensor types: oxygen electrode and screen-printed electrode (SPE).
• To provide a tool for at-site monitoring of transformer oil to prevent failures.

Main Methods:

• Development of two PPO sensors utilizing enzymatic oxygen consumption (oxygen electrode) or o-quinone reduction (SPE).
• Preparation of ex-service transformer oils via aqueous extraction or direct dilution in propan-2-ol.
• Comparison of sensor performance against the International Electrotechnical Commission (IEC) standard method.

Main Results:

• Both sensors demonstrated sensitivity and reliability in measuring phenol.
• The oxygen electrode sensor showed higher accuracy, especially at low phenol concentrations, compared to the SPE.
• The SPE offers greater simplicity for potential field-based applications.

Conclusions:

• PPO-based sensors provide a viable method for detecting phenol in transformer oils.
• The oxygen electrode sensor is more accurate, while the SPE is more suitable for on-site use.
• These sensors can serve as rapid screening tools for at-site monitoring, enhancing transformer reliability and reducing failures.