An imitation model of a power-supply system of oxygen-converter manufacturing to analyze switching overvoltage

Resumo

This paper considers switching overvoltage that occurs in the power-supply system of oxygen-converter manufacturing when a circuit vacuum breaker is triggered. The particular features of such systems are analyzed, and a typical power supply scheme is considered. It is noted that overvoltage manifesting a highfrequency behavior can be produced as a result of the peculiarities of arc interruption in vacuum (current chopping, voltage escalation, and arc reignition). Such overvoltage negatively affects electric motors with insulation that have the lowest margin of dielectric strength. Conventional means of overvoltage protection—such as conventional spark-gapped arresters, metal-oxide surge arresters, and spark gaps—are inefficient at high-frequency overvoltage because of a sharp increase in their voltage-second characteristics at low pulse duration. This paper suggests using RC circuits as protection from such overvoltage. Their application is accompanied by quite exact simulations since an incorrect choice of their parameters can worsen the commutation process. The main particular features of construction of a simulation model to study switching overvoltage and to analyze protection functioning are considered. A depiction of the simulation model and results of simulations are also presented. The validity of the suggested model is determined.