{'fraction_non_alphanumeric': 0.030726256983240222, 'fraction_numerical': 0.002793296089385475, 'mean_word_length': 5.595092024539877, 'pattern_counts': {'":': 0, '<': 1, '<?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}}
Microwave-based detection of internal defects in composite insulators for outdoor application

This paper introduces a non-destructive microwave-based detection method which was developed with respect to the detection of internal defects in composite insulators. The test equipment comprised a microwave-generating Gunn oscillator (frequency 24 GHz) combined with an open-ended rectangular waveguide as emitting and receiving sensor operating in the near-field (stand-off distance <; 5 mm). The received signal was converted to a dc voltage which correlated with the reflection coefficient of the waveguide's aperture. Measurements were performed with insulators that contained different artificial defects, i.e. strips of wood and copper and weak sheath-core adhesion. The results of measurements approved the suitability of the microwave-based test system for non-destructive detection of copper (conductive) and wood (non-conductive) defects in composite insulators. Further tests are required to evaluate the system's suitability for detecting weak sheath-core adhesion.