Transient control in low-voltage power installation networks and electronic systems

Sammanfattning: Transient protection in a low-voltage power installation network and an electronic system isof vital importance since most of the activities of our society are very dependent on thereliability of low-voltage power installation networks and electronic systems. This thesisconcentrates upon several investigations which all deal with the evaluation and improvementof the protection measures of low-voltage power installation networks and electronic systemsagainst electrical transients.Different components of transient protection circuits, such as varistors, gas dischargeprotectors and shielded cables, and their co-ordination in complex protection circuits havebeen experimentally investigated. The transient response of an individual protectioncomponent together with a complex protection system is discussed. Using a direct "high-level" current injection, a shielded system including non-linear circuit components wasevaluated experimentally. Based on the theoretical analysis, self-consistent time domainmodels of the varistor, the gas discharge protector, the power installation cable and theshielded cable were developed and implemented under the Alternative Transients Program -Electromagnetic Transients Program (ATP-EMTP). A good agreement was obtained incomparing the measured and the calculated results even for a complex protection circuit. Themodels developed in this thesis are shown to be a very efficient tool in the evaluation ofprotective measures in low-voltage power installation networks and in electronic systems.Different protection schemes for a protection circuit are also discussed in this thesis.A mid-plane triggered spark gap trigatron was also theoretically and experimentallyinvestigated. On the basis of these investigations, an optimised trigatron spark gap wasdeveloped and used in the construction of a new low impedance impulse current generatorwhich was used in the experiments described in this thesis.