Which statement is true about transformer insulation levels?

• A. High voltage has more insulation
• B. Low voltage has more insulation
• C. Insulation is equal for both voltages
• D. Insulation depends on weather

Answer: (A)

The main idea is that insulation strength scales with the voltage the equipment must withstand. Higher voltage creates greater electrical stress on insulation, so transformers designed for high voltage need insulation rated for higher dielectric strength, plus larger clearances and creepage distances to prevent breakdown. That’s why high voltage has more insulation.

Low voltage does not require more insulation than high voltage, and insulation levels aren’t the same for both voltages—the rating is chosen to match the voltage level, with environmental factors like moisture or temperature considered in the design margins but not as the primary driver.