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The imaginary part of the exponent indicates that the phase of the current density is delayed 1 radian for each skin depth of penetration. One full wavelength in the conductor requires 2 π skin depths, at which point the current density is attenuated to e −2 π (1.87×10 −3 , or −54.6 dB) of its surface value.
Later, cable theory with its mathematical derivatives allowed ever more sophisticated neuron models to be explored by workers such as Jack, Rall, Redman, Rinzel, Idan Segev, Tuckwell, Bell, and Iannella. More recently, cable theory has been applied to model electrical activity in bundled neurons in the white matter of the brain. [1]
The penetration depth for a good conductor can be calculated from the following equation: [5] =, where δ is the penetration depth (m), f is the frequency (Hz), μ is the magnetic permeability of the material (H/m), and σ is the electrical conductivity of the material (S/m).
High voltage is defined as any voltage over 1000 volts. [3] Those of 2 to 33 kV are usually called medium voltage cables, those over 50 kV high voltage cables.. Modern HV cables have a simple design consisting of a few parts: the conductor, the conductor shield, the insulation, the insulation shield, the metallic shield, and the jacket.
Penetrants, or penetrating items, are the mechanical, electrical or structural items that pass through an opening in a wall or floor, such as pipes, electrical conduits, ducting, electrical cables and cable trays, or structural steel beams and columns. When these items pierce a wall or floor assembly, they create a space between the penetrant ...
Coaxial cable, or coax (pronounced / ˈ k oʊ. æ k s /) is a type of electrical cable that has an inner conductor surrounded by a tubular insulating layer, surrounded by a tubular conducting shield. Many coaxial cables also have an insulating outer sheath or jacket. The term coaxial comes from the inner conductor and the outer shield sharing a ...
IEC 62067 Power cables with extruded insulation and their accessories for rated voltages above 150 kV (U m = 170 kV) up to 500 kV (U m = 550 kV) – Test methods and requirements; IEC 62068 Electrical insulating materials and systems – General method of evaluation of electrical endurance under repetitive voltage impulses
Variations in the electrical conductivity and magnetic permeability of the test object, and the presence of defects causes a change in eddy current and a corresponding change in phase and amplitude that can be detected by measuring the impedance changes in the coil, which is a telltale sign of the presence of defects. [5]