Determination of the striking distance of lightning to earthed structures

Abstract

A theoretical determination based upon a critical charge criterion and ionization processes is presented of the striking distance r s at which the upward leader is initiated from a struck object. The striking distance is shown to be leader-current dependent in the form r s ∝ i 2/3 . Comparisons are made with earlier, more numerically based models, which used an alternative equivalent-radius approach. The altitude dependence of the striking distance is also investigated. Since pressure, absolute humidity and temperature decrease with increasing altitude, the variation of streamer properties with altitude can be inferred from laboratory experiments. Calculations on this basis show that the striking distance increases significantly with increasing altitude, causing a corresponding increase in the risk of lightning strikes for given structures in mountain or aviation environments.

An Electro-Geometric Model for Lightning Shielding of Multiple Wind Turbines

“…in engineering is impractical. Dmax between two turbines can be approximately calculated according to the local altitude [28] because P, T and γ are related to the altitude HL as follows: condition with a value of 1 atm; and T0 is the temperature at sea level under standard atmospheric condition with a value of 293 K. According to the principle of lightning leader development reviewed in Section 2.3, we know that the value of Estr will affect the potential of leader head and the quantity of electric charge ΔQ newly generated by each step in the streamer area, and ultimately the development length of the UL. According to the simulation process shown in Figure 5 and Equation Error!…”

“…in engineering is impractical. Dmax between two turbines can be approximately calculated according to the local altitude [28] because P, T and γ are related to the altitude HL as follows: …”

Attachment of lightning flashes to grounded structures

“…This fact also brings serious doubts on the validity of leader inception models based on empirical equations or criteria taken from laboratory leaders when applied for lightning studies. This is the case of the critical radius concept [64] and the leader inception models of Rizk [70], Petrov and Water [96], and Bazelyan and Raizer [99].…”

“…Petrov and Waters [96] proposed a leader inception criterion based on the length of the streamer zone and the range of electric field intensification produced by the presence of a grounded object. For this reason, it is usually called the field intensification model [32].…”

Determination of the striking distance of a lightning rod using finite element analysis

“…Rizk also assumed that, for the initiation of a stable leader from the rod, potential difference and breakdown voltage of air or the electric field of the tip of the rod and the tip of the streamer must equal or exceed a certain critical voltage gradient or breakdown voltage. According to Petrov and Waters [12], the ambient electric field and the electric field generated by the structure must exceed a critical electric field over the streamer zone. The streamer initiated from a given point on a structure must extend to a critical length, which in their work was 0.7 m, before an upward leader is initiated from that point.…”