Quantitative detection of cellulose particles in transformer oil based on a lens-free holographic microscope

• Published in: Sensors and actuators. A. Physical. 2023-08, Vol.357, p.114396, Article 114396
• Main Authors: Li, Xinze, Peng, Yue, Zhou, Jiahao, Xue, Liang, Jiang, Chao, Jiao, Zhejing, Yang, Chuankai
• Format: Article
• Language: English
• Subjects: Cellulose particles; Lens-free holography; Transformer oil
• ISSN: 0924-4247; 1873-3069
• DOI: 10.1016/j.sna.2023.114396

The transformer oil’s insulation effect has a great impact on the safety of transformers. However, during the long-term operation of the transformer, the aging of the insulating paper will produce many cellulose particles，which reduce the insulation effect of transformer oil and cause transformer accidents. The present detection requires professional operation, expensive equipment and a stable environment. However, in this paper, we propose a lens-free wide field microscope for cellulose particles detection in transformer oil. Via experiments, we collected the holographic images of cellulose particles and recorded the intensity, and then recovered the phase information by angular spectrum theory reconstruction. Finally, based on the intensity and phase information, we can calculate parameters such as the area and volume of the particles. On the lens-free microscope, the enlarged shape and reconstruction distance of the particles can be used to tell cellulose from bubbles and other metal particles in transformer oil. This lens-free microscope not only features a large field of view, simple operation, and rapid measurement, but also provides a convenient way to accurately assess the condition of cellulose particles in power transformers and identify potential problems in advance. [Display omitted] •Applying lens-free holographic microscope to transformer oil particle detection.•High throughput rapid measurement of particles in transformer oil.•Bubbles and different particles in transformer oil can be distinguished.•Quantitative detection of cellulose particles in transformer oil.•Compared with the traditional methods, this method is cost-effective and efficient.