Latvian TSO awards contract to HHI for supply of autotransformers March 10, 2016 | Europe News Latvian transmission system operator (TSO) Augstsprieguma tīkls AS (AST) awarded a contract for supply of 330 kV autotransformers with capacity of 125 MVA for the Daugavpils substation. This content is available to only paying subscribers. Username or E-mail Password Remember Me Forgot Password