On-Site Testing of High-Voltage Unit Transformers with Increased Alternating Current

Over recent decades, there has been a gradual transition from scheduled preventive maintenance of power transformers to a system based on their technical conditions. This change reflects a move toward risk-oriented management of production assets, aiming to reduce operating costs. For aging power transformers, this approach involves extending their service life and increasing the reliability of their condition assessments. Comprehensive evaluations of power transformer conditions are carried out before commissioning, after repairs, and when extending service life, using high-voltage tests to measure partial discharge characteristics. Significant progress has been made globally in using mobile testing and diagnostic complexes (MTDCs) in testing power transformers at the installation site. The article discusses the key issues of performing high-voltage tests on power transformers at their operational sites. It covers the necessary regulatory and technical documents, various types of tests, the specified test voltages, and the requirements for test installations. The use of MTDC for testing power transformers at the installation site is also analyzed.