{'fraction_non_alphanumeric': 0.0183752417794971, 'fraction_numerical': 0.0, 'mean_word_length': 4.982658959537572, '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}}
Condition Assessment of Power Transformer on-Load Tap-Changers Using Wavelet Analysis and Self-Organizing Map: Field Evaluation

An on-load tap-changer (OLTC) is the most maintenance-intensive subassembly on a power transformer. Vibration monitoring is an effective technique that can be used to assess the condition of an OLTC effectively and nonintrusively. The authors have developed a condition monitoring system for common types of OLTCs that enables the condition of tap changer contacts and associated drive system to be inferred from vibration signals. A number of prototype systems have been installed onto OLTCs in distribution zone substations for field trials. Particular emphasis has been given to the detection of faults in a particular type of older tap-changer that had been prone to a range of faults associated with the switching contacts and drive mechanism. For this type of tap-changer, it is possible to determine not only that the tap-changer is aging but also to identify the particular part that is degrading.