Current wave and magnetic saw-effect phenomena in solid armatures

A theoretical model of the complete arcing transition sequence of solid armatures with resistive contact regions is proposed which includes evaluation of contact region melting, current wave, magnetic 'saw-effect' phenomena and current distribution at the contact surface. It is concluded that the velocity skin-effect (VSE) is the dominant mechanism influencing the arcing transition velocity though it is estimated that the latter could be increased to >2.5 km/s (as limited by the VSE) with resistive armature contact regions and the optimum combination of the critical parameters. For applications with bore sizes of about 90 mm previous theoretical predictions of the unsuitability of aluminium alloy as a contact region material, because of its relatively low resistivity, are confirmed.<
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