Characteristics of a chain element or rigid insulator
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Table 2 gives the main geometrical characteristics of insulators with ball-and-socket joints.

Among the values specified in insulator test standards, the most characteristic are :

• electromechanical or mechanical breaking load: for cap-and-rod insulators, this breaking load (expressed in kN) designates the insulator and defines the assembly standard (IEC 60120 publication);

• the following geometric dimensions :

  • the pitchp, which corresponds to the distance separating two homologous parts of two consecutive chain elements in a chain of insulators; this pitch can therefore be used to determine the length of a chain with a given number of insulators;

  • the creepage distance L_f main characteristic used to determine the pollution resistance of an insulator