Ratings, performance requirements, and compliance test methods are provided for ac high-voltage generator circuit breakers rated on a symmetrical current basis that are installed between the generator and the transformer terminals. Guidance for applying generator circuit breakers is given. Pumped storage installations are considered a special application, and their requirements are not completely covered by this standard.

The various asymetrical currents are all expressed with S-factors. They shall be transformed to the development concept to make the standard easier to apply in practice. The content will in principle not be technically changed.

The various asymetrical currents are now all expressed with S-factors and this created difficulties in the practical application of the standard. Furthermore, some of these factors make technically no sense. To avoid the confusion experienced in the past, all asymetrical currents shall be defined by using the d.c. component concept. Correction sheet will also be built in. This simplifies the application of the standard for the users to a great extent.