A porcelain suspension insulator uses a ball-and-socket design which puts the insulating material under ? to create strength.

• A. Compression
• B. Tension
• C. Strain
• D. Shear

Answer: (A)

Porcelain is very strong in compression but weak in tension. In a ball-and-socket suspension, the way the parts fit forces the load from the conductor to press the insulator pieces toward each other, creating compressive stress inside the insulating material. This compression helps the ceramic resist cracking and provides the needed strength. If the load placed the material in tension, the brittle porcelain would be more likely to crack. Strain describes deformation, not the primary stress state here, and shear isn’t the main mechanism strengthening the insulator.