8 t of square and are used as contactor in starters The most reliable high voltage circuit breaker are Air-circuit breaker Vacuum circuit breaker Oil-circuit breaker Gas circuit breaker e with the correct answer.

The correct answer is:<br /><br />Vacuum circuit breaker<br /><br />Explanation:<br />Vacuum circuit breakers are the most reliable high voltage circuit breakers. They use a vacuum as the interrupting medium to safely and efficiently interrupt electrical faults. Vacuum circuit breakers offer several advantages, including:<br /><br />1. High reliability: Vacuum circuit breakers have a long service life and are less prone to wear and tear compared to other types of circuit breakers. They are designed to withstand high mechanical and electrical stresses, making them highly reliable for use in high voltage applications.<br /><br />2. Low maintenance: Vacuum circuit breakers require minimal maintenance and have a lower likelihood of failures. They do not require regular servicing or replacement of interrupting media, as the vacuum itself serves as the interrupting medium.<br /><br />3. Fast fault interruption: Vacuum circuit breakers can quickly and effectively interrupt faults, minimizing the duration of the fault current and reducing the risk of equipment damage. This is important for protecting high voltage systems and ensuring safe operation.<br /><br />4. Compact design: Vacuum circuit breakers have a compact and space-efficient design, making them suitable for use in various high voltage applications where space is limited.<br /><br />In contrast, air-circuit breakers, oil-circuit breakers, and gas circuit breakers have their own advantages and disadvantages, but they are not considered as reliable as vacuum circuit breakers for high voltage applications.