As the scale of power grids expands

the problem of overproofed short-circuit current is intensifying

and adopting a fault current limiter is an effective method to solve the above problem. In order to ensure the insulation performance

the tank of the tank type fast vacuum breaker for the fault current limiter is filled with high pressure SF

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gas. Since the vacuum switch is under high pressure

the mechanical properties of the bellows will be greatly affected. In order to study the mechanical properties of the bellows under high pressures

a 3 D model of the bellows and its surrounding SF

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gas is first established

and then the bi-directional couplin

g method and dynamic mesh technology are used to study the pressure and velocity of the SF

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gas and the stress of the bellows during the compression of the bellows. The research results show that when the initial pressure of SF

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gas is 0.3 MPa

the pressure of SF

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gas increases by about 3.5%

the velocity of SF

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gas is about 15 m/s

and the maximum equivalent stress of the bellows occurs at the trough

which is about 1 GPa

during the bellows compression process. Therefore

it can be considered that the trough is the weak part of the bellows and will determine its mechanical characteristics. Through the bi-directional coupling simulation

the SF

6

gas movement process and the weak parts of the bellows are clarified

which lays a theoretical basis for further bellows design.