Релейний захист від електричної дуги та аварійного перегрівання елементів електроенергетичного розподільчого пристрою

Abstract

Relay protection against electric arc and emergency overheating of elements of a high-voltage switchgear, triggered with a high degree of reliability, was created by NUFT scientists when using a material with a shape memory (ESM) effect. Each metal and alloy has its own crystal lattice, the architecture and dimensions of which are predetermined. But in many me¬tals with changes in temperature, pressure, the lattice does not remain unchanged. In some moment its restructuring takes place. Such a change in the type of lattice, a polymorphic transformation, can be carried out in two ways. According to this scheme, the lattice is rearranged if the mobility of the atoms is diffusion, high enough to ensure their movement to new places. This is possible when a polymorphic transformation occurs at high temperature. This method was discovered during hardening. As a result of quenching, a phase is created with a new crystal lattice — martensite. The reverse transition of martensite to austenite (high-temperature phase) cannot pass through the "explosive" mechanism. It is necessary to significantly heat the alloy so that austenite crystals begin to emerge and grow in the depths of martensite. Moreover, their shape, as a rule, does not renew (atoms do not fall into place). If the lattice is so complex that there is no choice, there is only one way to reverse the restructuring — movement to ascending positions. Only in this case, the martensitic transformation provides the crystal with an ascending memory. Moreover, their shape, as a rule, does not renew (atoms do not fall into place). But the memory of a single crystal is not the memory of the whole volume. The alloy, as a rule, has a polycrystalline structure, consists of many individual crystals (grains), differing from one another in the orientation of the crystal lattices. Changing the shape of the entire sample will occur only if it is created a certain order in the placement of the crystals. It is ideally to orient all the crystals in one direction. During cooling, the atoms leave their old places and occupy new ones, they will move in the direction of action of an external force. Thus, the process of martensitic transformation causes atoms to move, and the external load sets the direction of movement.