The influence factors experiment of poor contact discharge in indoor power grid
In order to achieve monitoring on poor contact in indoor power grid and avoid electrical fires, the discharge phenomenon caused by poor contact is experimented systematically. A discharge experiment model of poor contact is developed, in which the influence of the structural parameters of contact type and the gap distance on poor contact discharges are experimented, and the influence of the operating parameters of load type (cos φ), load current and voltage phase are experimented too. The influence factors of initial discharge and the influence regular patterns with various parameters have been obtained from a large number of experiments. Statistical results show that the discharge trend increases first and then decreases. In the range of experiment load, poor contact discharge is very sensitive to the structure parameters of contact model, in comparison, it is not sensitive to operation parameters such as load type and load current. When the phase of experiment-voltage is in the vicinity of 0°, 60°, 120°, 180°, 240°, 300°, it has intensive discharge region of poor contact, and this phenomenon has the similarity under different factors.
The Electrical Contact Resistance of Two Rough Surfaces with Varying Phase Conductivity
Electrical contact materials deposited via thin-film processes enable the structuring of interfaces that optimize electrical contact performance. The performance gains are accomplished by structuring the contact material such that a conductive pathway is always present in the composite, a phenomenon related to the percolation threshold. The relationship between film composition and percolation threshold was explored by combined three-dimensional contact area and resistance modeling as well as experimental efforts. An optimal composite structure was found based on deposition parameters and compositional phase selections.
A higher dimensional theory of electrical contact resistance
The electrical contact resistance is computed for a local constriction of finite length and finite transverse dimension in a conducting current channel. Conformal mapping is used for the case of a rectangular channel. An analytic scaling law is constructed for the contact resistance over a wide range of aspect ratios between the constriction and the main current channel. The classical theory of Holm and Timsit is generalized to include finite length effects of the ldquoa-spotrdquo, defined as a small circular area of zero thickness through which current can flow. Potential applications and extensions of the theory are indicated.