In SQL Server you can use CONVERT function to convert an expression (a string i.e.) to TIME data type. In PostgreSQL you can to use CAST or various type conversion functions.
SQL Server:
-- Convert string to TIME SELECT CONVERT(TIME, '11:11'); # 11:11:00.0000000
PostgreSQL:
-- Convert string to TIME SELECT CAST( '11:11' AS TIME); # 11:11:00
For more information, see SQL Server to PostgreSQL Migration