Determination of the Place of Destruction of Electrical Apparatus Under Dynamic Influence of Short-Circuit Currents

The growth of short-circuit current levels in the power system of the Republic of Belarus requires studies of electrodynamic firmness parameters of the main structural elements of electrical installations with flexible conductors. During a short circuit in the power system, currents tens of times higher than the rated current can flow through the current-carrying part of the apparatus. When these currents interact with the magnetic field of other live parts, electrodynamic forces are generated. These forces tend to deform conductors of live parts and insulators on which they are fixed, as well as switching and measuring equipment. Convergence of conductors during a short circuit is accompanied by the occurrence of significant dynamic forces in them, transmitted to the gantries, supporting insulators and electric apparatus. Calculation of the main electric apparatus of open switchgear (OSG) for mechanical strength is currently performed only taking into account their static loading, for example, according to a given minimum static bending force. It should be noted that this representation does not take into account the dynamic effect of short-circuit currents, which in general case is a short-term impulse load that has a shock effect. The possible coincidence of one of the frequencies of forced oscillations with the natural frequency of oscillations of the apparatus is also not taken into account. In this case, the apparatus may be destroyed by even a very small force. In addition, attention should be paid to the fact that even in the absence of visible damage, the material of the apparatus housing during their long-term operation begins to deteriorate due to cracks, sinks, voids and other damage in the material structure, which steadily leads to a decrease in mechanical strength.