ASME PTC 20.2 - Overspeed Trip Systems of Steam Turbine-Generator Units PTC 20.2 - 1965

This standard is no longer an American National Standard or an ASME approved standard as of March 10, 2003. It is available for historical reference only. This Code is applicable to steam turbine generator units of 500 kw and larger and provides: (a) Recommended specifications for the performance of overspeed trip systems subject to modifications by mutual agreement between the parties concerned and (b) Standard procedures for acceptance tests to determine the performance of overspeed trip systems. The purposes of this Code are: (a)To establish guiding principles and specifications for overspeed trip systems that will apply to the equipment covered under this Code. (b) To establish test procedures to determine characteristics of overspeed trip systems: These include (1) Setting of overspeed trip (2) Short term deviation of trip speed. (3) Long term deviation of trip speed. (4) Signal transmission delay time. (5) Emergency stop valve(s) closing time.