Dry-type transformers for subtransmission

The development of a dry-type transformer for the 72.5kV voltage class was already presented at CIRED 2011 [1]. Since then, large interest has been shown by many utilities as well as industries, because of the benefits inherent to the dry technology, meaning superior safety for people, property and the environment. These features make these transformers particularly suitable for installations in the following applications: urban substations, substations located close to or in public or private buildings or in caverns, power generation plants, water protection areas and for industrial applications, especially in the chemicals, oil and gas segments. The availability of a dry-type on-load tap changer has supported the introduction of the HiDry⁷² transformer product in the market. First installations, routine and type tested, have taken place and are presented in the paper. The transformers are used in different indoor and outdoor applications.