Figure 4-25. - Post insulators for armless construction.
In figure 4-26 you see the common suspension insulator. The suspension insulator, as its name implies, is suspended from the crossarm and has the line conductor fastened to the lower end. It is designed for ease of linking units together. Linking of these insulators gives you the versatility of ordering one insulator to be used with varying voltages.
The strain insulator looks exactly like the suspension insulator but is designed to hold much heavier physical loads. Strain insulators are used when a pull must be carried as well as insulation provided. Such places occur whenever a line is dead-ended, at comers, at sharp curves, at extra long spans, at river crossings, or in mountainous country. In such places the insulator must not only be a good insulator electrically but it also must have sufficient mechanical strength to counterbalance the forces due to tension of the line conductors. (See fig. 4-27.)
Figure 4-26. - Suspension insulator.
Figure 4-27. - Strain insulator.Continue Reading