Calculation and Experimental Determination of Critical Sections of Electric Wires and Cables in the Circuits of Devices of High-Voltage High-Current Pulse Technique

Abstract

Purpose. Implementation of calculation and experimental determinations of critical sections and current densities in electric wires and cables of circuits of devices of high-voltage high-current impulse technique (HHIT), characterized flowing of pulse current i p (t) with different amplitude-temporal parameters (ATPs). Methodology. Electrophysics bases of technique of highvoltage and large pulse currents, theoretical bases of electrical engineering, bases of electrical power energy, technique of high electric and magnetic fields, and also measuring technique. Results. The results of the developed electrical engineering approach are resulted in calculation choice on the condition of electric explosion (EE) in atmospheric air of current-carrying parts of cable-conductor products of critical sections of S CCi of the uninsulated wires, and also the insulated wires and cables with polyvinyl chloride (PVC), rubber (R) and polyethylene (PET) insulation with copper (aluminum) cores (shells) on which in the circuits of HHIT the pulse axial-flow current i p (t) flows with arbitrary ATPs. On the basis of this approach the results of choice of critical sections S CCi are shown for the indicated electric wires (cables) of power circuits of HHIT with pulse current, ATPs of which with amplitudes of I mp =(0.1-1000) kA change on a аperiodic law or law of attenuation of sine wave in nano-, micrо-and millisecond temporal ranges. The results of calculation estimation of critical amplitudes of current densities δ CCi of-pulses of current i p (t) of the examined temporal shapes are presented in the indicated electric wires and cables of circuits of HHIT. By a calculation way it is set that critical amplitudes of current densities δ CCi of pulse current i p (t) for its indicated temporal shapes in the copper (aluminum) cores of the uninsulated wires and insulated wires and cables with copper (aluminum) cores (shells), PVC, R and PET insulation for nanosecond range are numerically 1176 (878) kA/mm 2 , for the microsecond range 64 (48) kA/mm 2 and for the millisecond range 1.29 (0.97) kA/mm 2. By the powerful high-voltage generator of current of artificial lightning experimental verification of applicability of the offered calculation relations is executed for the choice of critical sections S CCi and amplitudes of current densities δ CCi in wires (cables) at their EE. Originality. First by a calculation way for the specific temporal shapes of pulse currents i p (t) in the discharge circuits of HHIT, changing in nano-, micro-and millisecond temporal ranges with the wide change of the amplitudes I mp on an аperiodic law or law of attenuation of sine wave, the numeral values of critical sections S CCi and amplitudes of current densities δ CCi are obtained for the uninsulated wires, insulated wires and cables with copper (aluminum) cores (shells), PVC, R and PET insulation. Practical value. Application of the obtained results is in practice of tests of objects of electrical power energy, aviation and space-rocket technique on resistibility...

A Refined Mathematical Model of Physical Processes in a Conductor at a High-Current Pulse Discharge

“…Physical phenomena associated with the study of multiphysics processes occurring in conductors when pulse currents flow through them are relevant. This is confirmed by both International Standards [1,2] and a number of publications [3][4][5][6][7][8][9][10][11][12]. To the greatest extent, this concerns the study of the processes occurring in conductors during high-current short-term electrical discharges, which are accompanied by a number of complex and interrelated physical phenomena [9][10][11][12][13].…”

“…The processes considered in [3][4][5][6][7][8] concern "the execution of an approximate calculation of the critical and maximum permissible cross-sections and current densities in wires and cables". In a number of cases, the calculations are based on the introduction of "normalizing coefficients", which are introduced when determining the Joule integral ("action integral" in these works).…”

A Choice of Critical Sections of Electric Wires and Cables in Power Circuits of Electrical Equipment of Power Industry

“…Introduction. In [1] the results of a calculation and experimental determination of critical sections S Ci and critical amplitudes of current densities δ Ci for non-and insulated electric wires (cables) containing metal cores (i=1) and shells (i=2) and used in discharge circuits of high-voltage high-current pulse technology are presented. The basis for this choice of S Ci cross-sectional values of conductive wires (shells) and current density amplitudes δ Ci for cable-conductor products (CCP) with pulsed axial current varying in the nano-, micro-, and millisecond time ranges was known in electrophysics the electric explosion (EE) condition [2,3] of metal cores (shells) of the indicated wires and cables, leading to the sublimation of their current-carrying parts and the CCP failure.…”

“…In (1), the value of the current integral J li is calculated from the following analytical expression [3]:…”

“…where I mk is the amplitude of the steady SC current i k (t) in the power circuit of the electrical equipment; T a , T p are, respectively, the decay time constant of the aperiodic component and the period of oscillations of the periodic component of the emergency SC current i k (t) in the circuit with the CCP. Then, based on (1) and 3, the calculated expression for the integral of the action of the SC current i k (t) in power circuits with the CCP takes the following analytical form [7]…”