What is the maximum voltage rating for circuit breakers that use oil-filled bushings?

The maximum voltage rating for circuit breakers that use oil-filled bushings is indeed 230 kV. This type of bushing is designed to handle high-voltage applications, and 230 kV is within the operational range for oil-filled bushings, which are used primarily in substations and industrial applications where high voltage and reliable insulation are critical.

Oil-filled bushings support high voltage levels by providing excellent insulation properties while allowing electrical current to pass through. The oil serves to both insulate the conductive parts and dissipate heat, which enhances performance at higher voltages. Other options, while they may relate to different types of equipment or specific applications, fall outside the maximum limit for oil-filled bushings, which is why they are not correct in this context.