Types of insulators
(reference from GOST 27661-88 " Line suspended disk insulators ")

1.5. Insulator's type is determined by class, material of isolation part and it's shape.
1.6. Class of insulator respond to the standard of ultimate mechanical (for glass insulators) or electromechanical (for porcelain insulators) strength in kN and is chosen from the line: 40, 60, 70, 80, 100, 120, 160, 190, 210, 240, 300, 400 and 530.
Remark. Using insulators of classes 60, 80, 100, 190 and 530 is not recommend.
1.7. Isolation part must be manufactured from electro technical porcelain by GOST 20419-83 or electro isolation glass, hardened.
1.8. Mark of insulator must contain type and code of insulator.
Letters and digits of type indicates:
First - P - suspended;
Second - S or F - material of isolation part: S - glass, F - porcelain;
Third - V, D, K, S - marking of isolation detail shape: V - with longer shed, D - double wing, K - cone, S - spherical;
Digits - 40, 70 Е.400 - class of insulator;
Forth, following after digits - A, B, V, G Е - index of insulator modification.

Advantages of glass insulators against to porcelain ones

Already first years of production and operation of the glass insulators show some their advantages in comparison with the same porcelain types:

• row materials, used in manufacturing of glass insulators have more stable components than those used for porcelain insulators production, providing good conditions for stabilization of glass insulator characteristics and technological processes;
• technological process of glass insulators production could be mechanized and could be under automation control, eliminating the influence of human factor to the characteristics of insulators;
• the electromechanical characteristics of hardened glass are higher than those of porcelain. It allows to manufacture insulators with necessary mechanical strength, their dimensions and weight being lower than those of the same porcelain types;
• the testing of hardened glass insulators is simpler in both production and operation processes;