Diagnostic Measurements on Rotary Arcs in Hollow Polymeric Cylinders

Abstract

Rotary arcs in hollow polymeric cylinders have been monitored using electrical and optical techniques. The arcs burning within hollow cylinders were driven by electromagnetic forces. The arc voltage, current, dielectric strength below the arc gap, the optical emissions from the chamber were measured along with high-speed photography. The diameters of the hollow cylinders and magnitude of the applied magnetic field were varied. The arc voltage, especially the extinction peak prior to current zero, increased for larger bore cylinders and higher magnetic fields. By comparing the arc voltage waveforms and arc photographs, this was shown to be because the arcs were elongated. Luminosity was detected even after current zero, when polytetrafluoroethylene was in the arc chamber. The extensive experimental results obtained have enabled empirical mathematical expressions to be derived which yield approximate indications of current interruption capabilities under different operating conditions.

Two-dimensional electron density characterisation of arc interruption phenomenon in current-zero phase

“…Therefore, higher interruption success rates with increasing ε were achieved by larger arc surface areas and weaker electric fields applied to the periphery of the gap. On the other hand, higher arc voltages for longer arc lengths in previous studies [37,38] were not observed in this research, because considerable stretch of arc lengths due to the arc looping did not occur in the 3 mm-short-gap arcs.…”

Convoluted Arc With Flux Concentrator for Current Interruption

“…EVERAL evolving aspects of high voltage current interruption which are currently commanding attention include the interruption of direct currents (D.C.) rather than alternating currents (A.C.) and the drive towards avoiding the use of sulfur hexafluoride (SF6) gas as an arc quenching agent because of its potential for causing Global Warming [1]. Meanwhile, technology based upon the evolution of various forms of electromagnetic control of electric arcs has been investigated over several years with potential for current interruption applications [1][2][3]. Examples of particular forms of such devices include, as well, an electric arc convolute rotating around a polytetrafluoroethylene (PTFE) cylinder housing a magnetic field (B-field) producing coil, a similar arrangement with an outer PTFE cylinder with the arc rotating in the annular gap between the outer and inner PTFE cylinders etc.…”

“…With the concentrator inner radius R3, maximum secondary current2 i in the flux concentrator (Fig. 4), and permeability of free space o is the effective inductance of the flux concentrator, is the self-inductance of the central high filed region [7], i 1 is a primary current through the arc and B-field coil (which are connected in series) and '  is the transfer inductive energy loss between the B-field producing coil and the central high field region (b = 0.03m, Fig.…”