Abstract The insulation performance of Current Transformers (CTs) is very important for their operational reliability. When the insulating oil in CT deteriorates, it has to be replaced by new oil, which is a costly solution. In this paper, a new technique for recovering insulating oil properties is proposed by using nanoparticles to form what is called nanofluids. For the first time, a real aged CT was used for the experimentation. Different insulation tests were carried out, breakdown voltage test on oil samples as well as dissipation factor, insulation resistance, and conduction current on the terminals of the CT itself. The aged insulating oil was first extracted from the aged CT, and then nanofluids were prepared by direct mixing of the oil with titanium oxide (TiO2) nanoparticles followed by ultrasonic processing for proper dispersion of nanoparticles. Different concentrations of nanoparticles were considered. After that, the CT was refilled with the prepared nanofluids. The experimental results either for the nanofluids or for the nanofluids-filled CT were compared to corresponding ones for the aged oil. The results indicated a great improvement in the breakdown voltage of the oil and in the insulation performance of the CT as a whole. Physical mechanisms behind the obtained results have been discussed.

中文翻译：

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使用纳米流体提高老化电流互感器的绝缘性能

摘要 电流互感器（CT）的绝缘性能对其运行可靠性非常重要。当 CT 中的绝缘油变质时，必须更换新油，这是一种成本高昂的解决方案。在本文中，提出了一种通过使用纳米颗粒形成所谓的纳米流体来恢复绝缘油特性的新技术。首次使用真正的老化 CT 进行实验。进行了不同的绝缘测试，油样的击穿电压测试以及CT本身端子的损耗因数、绝缘电阻和传导电流。老化绝缘油首先从老化的CT中提取，然后通过将油与二氧化钛 (TiO2) 纳米颗粒直接混合，然后进行超声波处理以使纳米颗粒适当分散来制备纳米流体。考虑了不同浓度的纳米颗粒。之后，用制备的纳米流体重新填充 CT。将纳米流体或纳米流体填充 CT 的实验结果与老化油的相应结果进行比较。结果表明，油的击穿电压和 CT 的整体绝缘性能都有很大的提高。已经讨论了所获得结果背后的物理机制。将纳米流体或纳米流体填充 CT 的实验结果与老化油的相应结果进行比较。结果表明，油的击穿电压和 CT 的整体绝缘性能都有很大的提高。已经讨论了所获得结果背后的物理机制。将纳米流体或纳米流体填充 CT 的实验结果与老化油的相应结果进行比较。结果表明，油的击穿电压和 CT 的整体绝缘性能都有很大的提高。已经讨论了所获得结果背后的物理机制。