What is the role of the polymer core in a composite insulator?

• A. The polymer core provides weather resistance only.
• B. The fiberglass core provides high mechanical strength while the silicone rubber housing provides electrical insulation and weather resistance.
• C. The core stores energy to compensate for surges.
• D. The core determines color of insulator.

Answer: (B)

In a composite insulator, the rod in the center is the primary load-bearing part. It’s typically fiberglass, a polymer-based composite that delivers high mechanical strength and stiffness to resist bending, wind, ice, and the tension from the conductor. The outer silicone rubber housing surrounding that core provides electrical insulation and weather resistance. It creates a hydrophobic, self-cleaning surface that minimizes leakage current and protects against moisture and contamination. The core isn’t responsible for insulation or weather protection, nor does it store energy or determine color. So the core’s role is to supply the mechanical strength and structural integrity, while the outer silicone layer handles insulation and weather performance.