Breakdown process on rod–rod air gap under oscillating lightning impulse voltage

Abstract

This study presents the discharge process on rod-rod electrodes under oscillating lightning impulse voltage. For this purpose, a measurement system has been developed to record the discharge currents at both rod electrodes simultaneously and to photograph the spatial propagation of the discharges. The measurement results of the discharge process are shown for an air gap of s = 150 cm and for a superimposed frequency of f = 200 kHz. Like the standardised lightning impulse voltage, three consecutive phases of discharge have been identified before a breakdown occurs. These are streamer discharge phase, channel transition phase and channel formation phase. The three phases are described, interpreted and their correlation is shown. On the basis of the oscillations, the discharge processes recur periodically if the momentary voltage is higher than the mean curve of the oscillating lightning impulse voltage. The streamer discharge emerges foremost at the positive rod electrode and propagates toward the grounded rod electrode. Its propagation depends on the voltage crest value. Arriving at the grounded rod electrode, the channel transition phase begins. There the discharge moves back to the positive rod electrode due to recombination and generation. Then the discharge constricts to the positive rod electrode, which forms a channel. Simultaneously, at the grounded rod electrode, a channel is also emerging. In each period, the channel will build up stepwise. The channel leads to the main discharge of the oscillating lightning impulse voltage.

Simulation of positive streamer propagation in an air gap with a GFRP composite barrier

“…The positive space charge generated by the streamer discharge can deposit on the inner surface of the blade, strengthening the electric field on the exterior surface of the blade and thus triggering a secondary streamer discharge. Since the length of the secondary streamer on the exterior - 11 surface of the GFRP blade may reach the order of a metre, the positive surface charge density on the inner surface and the negative surface charge density on the exterior surface of the GFRP blade may reach high magnitudes. The blade tip with a small GFRP blade thickness can bear a stronger average electric field than the blade root with a large thickness.…”

“…The current of the lightning return stroke can heat and expand the breakdown pores in the composite layer, which results in puncture damage to the blade. Discharge experiments in a long air gap have been carried out to investigate the electric breakdown of wind turbine blades during natural lightning strikes [11]. Yokoyama studied the lightning attachment to a 3-m GFRP blade sample [12].…”

Schlieren techniques for observations of long positive sparks: Review and application

“…The following breakdown phase is evitable when the streamer corona finally reaches the grounded plane [30]. The thin channel with high electrical conductivity bridges the high voltage (HV) electrode and the grounded plane.…”

“…Discharge processes with light-emitting have been extensively observed and studied by using optical imaging techniques, for example, streak camera [12,36], high-speed video camera [18,[37][38][39], or intensified charge-coupled device (ICCD) camera [30,40]. However, limited studies exist on lightless phases like dark periods or insulation recovery phases during which the thermodynamics process is predominant instead of the ionization process.…”

Adaptive strategies to fast multipole method in photoionisation calculations for streamer discharges

“…Streamer discharge is an important building block of gas discharges. As a natural phenomenon, it is the precursor of sparks [1,2] and lightning leaders in lower altitude [3][4][5][6][7] and can also be observed and captured directly, for example, the sprites in high altitude [8,9]. As a product of streamer discharges, the non-thermal atmospheric plasma paves the way to a large number of chemical reactions in applications such as the pollution control [10], solubilisation of carbon nano-material [11,12] and disinfection [13,14].…”