Peak voltages with D-C arc interruption for aircraft

Abstract

D URING the interruption of direct currents in circuits having induct ance, the presence of high-voltage peaks or "inductive kicks" is quite commonly recognized in a qualitative sense. There is however little quantitative data on this subject, particularly at the voltages, loads, and altitudes encountered on modern aircraft.Data on inductive voltages usually are obtained by taking cathode-ray oscillograms or by observing a cathode-ray os cilloscope. The former method is accu rate but relatively slow and tedious ; the latter, with the tubes available up to this time, has been somewhat questionable because of the difficulty of clearly deter mining by eye a single fast transient. In this investigation use has been made of a cathode-ray tube with a retentive screen-so retentive that the trace of a single half-cycle sweep of a 60-cycle wave takes several seconds to disappear. Using this tube it has been possible to take a large amount of data in a short time, so that, instead of relying on a few oscillograms, ten readings could be taken at each point and an average and range established for the voltage disturbances set up. Scope of This PaperIt is the purpose of this paper to pre sent experimental data on the magnitude and variations of voltage peaks set up by d-c arc interruptions of inductive circuits. These voltages were measured on d-c systems of 30, 60, 125, and 250 volts with currents ranging from 0.1 to 220 amperes and simulated altitudes from sea level to 50,000 feet. The loads used included typical aircraft devices such as motor fields and contactor coils.The effect of the induced-voltage peaks on insulation puncture or flashover was not investigated. This phase of the sub ject requires a separate investigation.Because of limits in time, no attempt is made to explain theoretically the re sults obtained. Rather, emphasis is on the presentation of data taken to date.Paper 44-200, recommended by the AIEE com mittee on air transportation for presentation at the

Stability, spatial extension and extinction of an electric arc in aeronautical conditions of pressure under 540 V DC

“…For every current values considered in this work, electric arc is even more unstable as the pressure is high and the mean stability length is in the range [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16] cm. The influence of arc current intensity is more pronounced for pressure values below 6 Â 10 4 Pa.…”

“…These parameters taken into account are the following: the supply voltage, the intensity of the arc current, the pressure value, etc. [3][4][5][6] to find works dealing with our experimental conditions. These works concerned traction systems and avionics.…”