標準號：IS 3716-1978
發布日期：1978/12/1 12:00:00
實施日期：1999/12/31 12:00:00
適用范圍：1.1 This standard provides guidance on the selection of the electric strength of equipment, of surge arresters or protective gaps, and of the most suitable degree of switching overvoltage control. The rated with-stand voltages of the equipment are covered in IS : 2165-1977〓 which forms a necessary adjunct to this standard.Note — This guide is based on apparatus types and ratings in use at present. As new equipment and equipment characteristics are developed and proved, this guide should not be interpreted as a limit to their adoption.1.2 This guide covers only phase-to-earth insulation and deals separately with the three following ranges of the highest voltage for equipment:a) Range A: above 1 and less than 52 kV.b) Range B : from 52 to less than 300 kV.c) Range C: 300 kV and above.1.3 It covers installations of all kinds and in all situations involving voltages higher than 1 kV, whether they are exposed to lightning or not, with the exception of overhead lines. However, the test procedures apply to the latter also.