Possible Reasons Why Calculations Of Inductive Interference Pipeline Voltages Are Higher Than Conducted Measurements
Proceedings Publication Date
Christian Wahl
Christian Wahl, Ernst Schmautzer
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Due to bundled energy routes, high voltage energy systems (e.g. overhead lines) are often located near buried isolated metallic pipelines. Thus, a possible high inductive interference from energy systems may produce hazardous AC pipeline voltages. High induced voltage levels can cause dangerous high touch voltages and AC material corrosion. Therefore, European standards limit the allowed maximum voltages for long and short term interference. Consequently, pipeline interference calculations are necessary to survey if given limits are exceeded. Unfortunately, the results of these – standardized – calculations are often higher than conducted measurements on pipelines, despite using state of the art calculation parameters. Investigations on this discrepancy are needed to bring calculations and measurement data closer together to avoid excessive measures which are often cost-intensive. Even with experience, it is difficult to identify the very well hidden, but crucial factors for the discrepancy on specific calculated and measuring positions. The following factors are suspected to have different degrees of impact on induced pipeline voltages and have to be considered individually and with each other: • Load current instead of using the maximum operational currents • Reduction effect of global earthing systems • Reduction effect of local earthing systems • Reduction effect of practically achievable pipeline earthing systems • Reduction effect of pipelines, running in parallel • Reduction effect of parallel high voltage power systems with grounding conductors • Incorrect or inadequate pipeline coating parameter • The influence of the model-conform specific soil resistivity

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