What voltage range typically uses circuit breakers with solid porcelain bushings?

The use of solid porcelain bushings is commonly associated with electrical systems operating at medium voltage levels, specifically around the 20 kV range. Solid porcelain is a durable, insulating material that can withstand the stresses of electrical insulation at these voltages. At this level, circuit breakers need to be robust enough to handle transmission and distribution applications, and solid porcelain bushings provide the necessary mechanical and electrical properties for reliability and safety.

Using solid porcelain for bushings in this voltage range offers advantages, such as excellent dielectric strength and resistance to environmental factors, making them suitable for outdoor installations. This is why the correct answer identifies 20 kV as the typical voltage that utilizes circuit breakers equipped with solid porcelain bushings, aligning with industry standards and practices. Higher voltage levels generally require different bushing types that can manage increased electrical stress and thermal considerations.