CURRENT LIMITATION BY HIGH TEMPERATURE SUPERCONDUCTORS AND BY CONDUCTING POLYMERS

摘要

The transition of materials from zero or low resistivity to comparatively high resistivity may be utilized for current limitation, enabling permanent fuses that don't have to be replaced after short circuit operation. This paper deals with two principles - superconductors and conducting polymers - and reports about experiments and simulations.rnMainly two ways are known to limit short circuit currents by using superconductors, the inductive and the resistive one. This paper concentrates on the resistive limiter. It directly uses the transition from superconductivity to normal conduction. Measurements of the resistivity of high temperature superconductors as a function of temperature and current density are presented. Based on these data, the performance of resistive limiters is simulated and the consequences are discussed.rnConducting polymers with a temperature-dependent transition from low to high resistivity are a similar way to limit short circuit currents. Based on measurements of the thermal and electrical properties of such polymers, the current-limiting behavior is simulated as well. The results are in good accordance with switching tests in a low voltage circuit.