Who are major manufacturers of oil immersed transformers?

Major manufacturers include large global power equipment companies and established transformer OEMs that produce oil immersed power and distribution transformers. Commonly recognized names include Hitachi Energy, Siemens Energy, GE Vernova, Schneider Electric, and several major regional transformer manufacturers. The right choice depends on voltage class, standards compliance, delivery capability, service network, and utility approvals in the target country.