scope:

Purpose and Extent

Overspeed may result, for instance, from disturbances due to an Interruption in the energy transfer from the turboset to the connected consumer. Safety systems (e. g. speed Controllers) and protection systems (e. g. overspeed trips) serve to keep the deviation from the operational speed after such a disturbance within allowable limits, or eise to prevent an inadmissible overspeed by a timely switch-off of the turboset using the emergency stop.

It is the purpose of the guideline presented to fix the conditions, the extent and the sequence of the tests, as well as the procedures for the assertion of the designappropriate and safety-related properties of these control systems.

Feedforward control systems are included in this guideline insofar as they complement the control systems dealt with, i. e. for Umiting and switch-off interaction in case of ränge transgressions and malfunction, respectively.

Functional proof is obtained - on the one hand - by subsystem testing and - on the other hand - by tests ascertaining the non-transgression of allowable over¬ speeds. The latter are carried out in connection with turbine trip and load shedding tests of the turboset. By fixing the sequence of these tests, an extrapolation to the most unfavourable disturbance - load dump from füll load to no-load under speed control failure - becomes possible.