The paper describes the dynamic characteristics of square and circular permanent magnet mechanisms. On condition of satisfying the dynamic characteristics of vacuum circuit breaker

the masses of iron core and permanent magnet

the size and the total weight of the mechanism with circular structure are obviously less than those with square one. Furthermore

compared with the square structure

consumption energy and the peak value of the operation current with the circular structure are less too. On the other hand

the structure with the square type is more flexible. Its width can be extended to meet the requirement of the mechanism roomsize while the length remains unchanged. Meanwhile

it is easier to develop a series of products.