This part of International Standard IEC 71 applies to three-phase a.c. systems having a
highest voltage for equipment above 1 kv.
It specifies the procedure for the selection of
the standard withstand voltages for the phase-to-earth, phase-to-phase and longitudinal
insulation of the equipment and the installations of these systems.
It also gives the lists of the standardized values from which the standard withstand voltages shall be selected.