{'fraction_non_alphanumeric': 0.020239190432382703, 'fraction_numerical': 0.01839926402943882, 'mean_word_length': 5.044444444444444, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
Research on AC and High Frequency Breakdown Characteristics of Oil-paper Insulation of 220 kV Current Transformers

The AC Breakdown test at 20 °C, 50 °C and 80 °C and the high-frequency breakdown test at 5 kHz, 10 kHz, and 14 kHz of the oil-paper insulation of the 220 kV current transformer with different thermal aging time is investigated. The breakdown characteristics were explored, and the Weibull distribution was used to process the data. As the aging time increases and the test temperature increases, the AC breakdown strength of oil-paper insulation continues to decrease, and the increase in temperature has a significantly greater impact on the insulation strength than the aging time. With the increase of the voltage frequency, the breakdown field strength of the sample continues to decrease, and with the increase of the aging time, the resistance of the insulating sample to high-frequency voltage gradually becomes worse. The results can provide theoretical support for the safe operation of 220 kV current transformers at different temperatures and high frequencies.