Fiber reinforced plastic（FRP）has no way to meet the explosion-proof requirements of short circuit explosion of 220 kV cable joint

and the direct opening energy release method of the Aluminum-Magnesium alloy explosion-proof device is not waterproof and moisture-proof and is impossible to control the spray from explosion. In this paper

the spring contraction energy release mode for the Aluminum-Magnesium alloy protection device of 220 kV cable joints is proposed

that is

a cover plate is added to the energy release hole and is tightened by the spring. When the joint shorts and explodes

the spring acts and release the energy. By analyzing the principle of the spring’s contraction energy release mode

its design method and design principles of key parts are given. Using the finite element calculation method of temperature field

flow field and displacement field coupling

the optimum opening radius of the energy release hole is determined to be 80 mm. The obtained elastic coefficient of spring is 7.56×104N∕m. Taking the fracture stress of the maximum stress value less than 5 series Aluminum-Magnesium alloy material as the criterion

the best matching wall thickness of the explosion-proof device is determined to be 8 mm. The blasting test of 110 g8701 explosive with equivalent arc energy proves reliability of the design. The protection device of the spring contraction energy release mode has waterproof and moisture-proof performance

can further reduce the secondary damage caused by the spray during short circuit explosion and can provide a theoretical basis and method guidance for the explosion-proof design of the protection device of transmission cable joint.