The solution of the current scientific and applied problems is discussed: prevention of the ignition of explosive gas mixture in the process of work of the low-current circuit and safety increase due to studies and substantiation of the possibility to use the methods of intrinsically safe calculation for power supply sources with advance shutdown.
The analysis is conducted concerning the methods of intrinsic safety estimate of power supply sources with advance shutdown. The features of the two methods of estimation based on computer simulation of the arc switching process in electrical circuits using the Micro-Cap package, as the most appropriate, are shown.
The results of the experimental studies of the dynamics of changes in the values of the thermal time constant throughout the entire arc discharge in the low-current circuit became the basis for specifying one of the considered computational methods for intrinsic safety estimate. This allowed to increase the convergence of the simulation results with respect to the minimal igniting parameters of the circuit and the energy indices of the experimental data. The error of the calculation results based on the improved model and the minimum igniting parameters at the estimate of power supply sources with advance shutdown is no more than 7.6 %. In this case, the error in determining the minimal igniting parameters by simulation of the unspecified known computational method for estimation of intrinsic safety and the experiment reached 11.5 %.
In all ranges of speeds, the energy indices obtained in the simulation are close to the experimental ones, which indicates the use of the refined model as more accurate in assessing the intrinsic safety of power supply sources with advance shutdown.
Based on the example of the second of the considered computational methods, it is shown that in the case of neglecting the dynamics of changes in the values of the thermal time constant over the whole period of the arc discharge, significant errors (up to 517 %) are introduced into the definition of the minimal igniting currents during simulation.