This is a major repair category in 2018 managed by Power Transmission Company 1 (PTC 1). After more than 20 years of operation and through various periodic experiments as per its process, this is the first time the transformer has been grid-separated and completely overhauled.
220kV - 250MVA AT4 transformer manufactured by AEG-ETI of Turkey is one of three major transformers at Ha Dong 220kV substation. The high-capacity transformer is located at the extremely crucial node of power supply to Ha Noi capital, therefore, long-term power outage from the transformer for overhaul is very difficult with a large amount of work, related to other equipment, performed under live-substation conditions.
During the performance, the overhaul items are conducted step by step in compliance with the sequence in its approved option. On-site inspection and monitoring are seriously performed with the proper coordination between experienced and highly-professional units, therefore the transformer energized is ensured with technical requirements, on schedule and absolutely safe for human and equipment.