This International Standard applies primarily to constant-speed steam turbines driving a.c. generators at power stations, for testing speed control systems consisting of speed governing and overspeed protection systems. It may also be used, where appropriate, for other types of steam turbines. The purpose of acceptance tests of steam-turbine speed governing and overspeed protection systems is to verify any criteria quoted in the manufacturer's guarantees. Such tests will generally be carried out to check compliance with IEC 45-1. The criteria may include: a) steady-state speed regulation (speed governing droop); b) steady-state incremental speed regulation (incremental speed governing droop); c) range of speed at no-load corresponding to the extreme settings of the speed changer; d) dead band of the speed governing system; e) stability of the speed governing system; f) maximum transient increase of speed following full load rejection and any partial load rejections, with the speed governing system in operation; g) overspeed trip setting; h) maximum transient overspeed following full load rejection on the failure of the speed governing system. Selection of the tests to be carried out and procedures for other tests not covered by this specification shall be agreed upon between the manufacturer and the purchaser.