Effects of Lightning in Oil Plants Construction Sites – Step and Touch Voltage Simulation and Tests in Work Footwear Hélio E. Sueta¹, Miltom Shigihara¹, Luis E. Caires¹, Geraldo F. Burani¹ ¹Institute of Electrotechnics and Energy, University of Sao Paulo IEE/USP Sao Paulo, Brazil e-mail: sueta@iee.usp.br Wallace J. D. Nascimento² ²Petróleo Brasileiro S.A. PETROBRÁS Duque de Caxias, Brazil e-mail: wdamasceno@petrobras.com.br Abstract— This paper presents a study on the effects caused by indirect lightning on oil refinery construction site workers. We made some tests on work footwear, commonly used by workers in these refineries, and some simulations for a specific site for the evaluation of step and touch voltages. Keywords- lightning protection, refinery site, high voltage tests, computational simulations I. INTRODUCTION As a complement to the study of direct and indirect effects of lightning on oil refineries workers [1], we carried out studies in work footwear worn by oil refinery workers. Also, we made a withstand impulse tests at the IEE-USP and computer simulations in order to verify both touch and step voltages. We tested two types of work footwear from different manufacturers. One of them was brand new and the other one had already been worn. Both are CA-certified (such verification was made through printed numbering on the samples checking). The purpose of these tests was to verify withstand impulses in samples sent by the Duque de Caxias Refinery (REDUC), owned by Petrobras. Regarding the tests, the procedure used was different from those recommended by the standards of high voltage, as these are made in power frequency (50 Hz or 60 Hz), to be used in test voltage (usually 14 kV) for a minute, with the measurement of leakage current. The purpose of the tests carried out at the IEE-USP was to verify the step and occasionally touch voltages withstand concerning lightning. In this sense, the procedure used was different from the standardized one. In addition, some simulations were performed to assess stress levels (magnitudes) that can occur in a section of a typical mesh, due to an incidence of lightning in an oil refinery site (ground level or in a typical structure). The potential levels were calculated based on the point of incidence of lightning through a suitable computer program. II. METHODOLOGY Initially, we present results obtained through tests performed on two types of work footwear. Such data relates to disruptive voltage taking place at the shoes soles and sides. Subsequently, we compared these results with those obtained in computer simulations performed using software CDEGS ®. The input parameters used in the software were obtained through a report on the earthing of a Petrobras refinery site [2]. III. IMPULSE AND HIGH VOLTAGE - TESTS AND RESULTS Tests were conducted on two types of footwear: (1) new shoes, brand Conforto, Size: BR 43, EU 45, biodensity, Shock absorber, B. ACO, CA 7237 N43, LOT 250309; and (2) already worn shoes, brand BOMPEL, Size EUR 43, BRA 41, OIL RESISTANT, CA 8681 09 10, LOT 31840 41. The following tests were carried out with both pairs of shoes: • Footwear (1): Impedance (characteristic of the sole), verification of impulse voltage perforation, verification of disruptive voltage at 60 Hz; • Footwear (2): verification of impulse voltage perforation; determination of 50% dry lightning impulse flashover voltage using increase and decrease method. Figure 1 shows the pair of shoes (2) subjected to the tests. Note that a metallic foot was inserted inside the shoes simulating the foot of a person 2011 International Symposium on Lightning Protection (XI SIPDA), Fortaleza, Brazil, October 3-7, 2011. 78