IS 6307 specifies porcelain insulators used on overhead power lines for both transmission (HT) and distribution (LT). Covers disc/suspension type for HT lines and pin type for LT lines.
Specification for porcelain insulators (disc, pin, and post type) for overhead power transmission and distribution lines.
Key Values
Disc insulator flashover (dry)Min 80 kV
Disc insulator flashover (wet)Min 50 kV
Mechanical failing loadMin 70 kN (standard disc)
Practical Notes
! Disc insulators are strung in series — more discs = higher voltage rating. 11kV needs 1 disc, 33kV needs 3, 132kV needs 9.
! Damaged or cracked insulators must be replaced immediately — they can cause flashover and line faults.
! Always test insulators before installation — reject any with visible cracks, chips, or uneven glaze.