Electrical engineering & Electromechanics (Apr 2019)
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 ip(t) with different amplitude-temporal parameters (ATPs). Methodology. Electrophysics bases of technique of high-voltage 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 SCCi 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 ip(t) flows with arbitrary ATPs. On the basis of this approach the results of choice of critical sections SCCi are shown for the indicated electric wires (cables) of power circuits of HHIT with pulse current, ATPs of which with amplitudes of Imp=(0.1-1000) kА 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 δCCi of -pulses of current ip(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 δCCi of pulse current ip(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) kА/mm2, for the microsecond range 64 (48) kА/mm2 and for the millisecond range 1.29 (0.97) kА/mm2. 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 SCCi and amplitudes of current densities δCCi in wires (cables) at their EE. Originality. First by a calculation way for the specific temporal shapes of pulse currents ip(t) in the discharge circuits of HHIT, changing in nano-, micro- and millisecond temporal ranges with the wide change of the amplitudes Imp on an аperiodic law or law of attenuation of sine wave, the numeral values of critical sections SCCi and amplitudes of current densities δCCi 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 to action of pulse currents ip(t) with different ATPs of natural (currents of the imitated lightning) and artificial (discharge currents of HHIT) origin will be instrumental in the increase of electro-thermal resistibility of the uninsulated wires, and also the insulated wires and cables with PVC, R and PET insulation of HHIT widely applied in power circuits.
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