HD 540.2 S1:1991

Insulation co-ordination - Part 2: Application guide HD 540.2 S1:1991

Scope

This publication provides some guidance on the selection of the electric strength of equipment of surge arresters or protective spark gaps and on the extent to which it will be useful to control switching overvoltages - The object of this publication is not to give strict rules for insulation co-ordination and design but to provide guidance toward rational and economical solutions - Therefore it is intended to consider only a few basic cases in this publication it being evident that installations constituting exceptions to normal design or included within systems having exceptional characteristics will require special study by experienced engineers - This application Guide is based on apparatus types and ratings in use at the time of publication - As new equipment and equipment characteristics are developed and proved this guide should not be interpreted as a limit to their adoption - Like Publication 71-1, Publication 71-2 covers only phase-to-earth insulation - Like Publication 71-1, Publication 71-2 deals separately with the three following ranges of the highest voltage for equipment: 1) Range A: above 1 kV and less than 52 kV * 2) Range B: from 52 kV to less than 300 kV * 3) Range C: 300 kV and above - It covers installations of all kinds and in all situations involving voltages higher than 1 kV whether or not they are exposed to lightning with the exception of overhead lines - However the test procedures apply also to the latter