May 22, 2017
Environmental pollution has caused the research to find solutions to reduce air emissions which leads to an increase in the EV used. Electric vehicles need battery recharge; therefore, the number of charging stations increases proportionally.
As any electrical installation, charging stations need a high-quality grounding and protection from external hazards, e.g. direct lightning strike.
Our Technical Center has received a request to calculate the lightning protection and grounding system for EV charging stations. We offer the following solution for this task:
- facility - EV charging station;
- soil type used for calculations - clay loam (100 Ohm*m);
- dimensions are shown in Figure 1.
Figure 1. Facility dimensions (in mm)
- calculate the system of external lightning protection;
- calculate the grounding arrangement.
The activities were performed in accordance with the Electrical Installations Code (EIC) Rev. 7, SO 153-34.21.122-2003 Guidelines for Arrangement of Lightning Protection of Buildings, Structures, and Industrial Utilities (hereinafter referred to as SO) and RD 34.21.122-87 Guidelines for Arrangement of Lightning Protection of Buildings and Structures (hereinafter referred to as RD).
Protection of buildings against lightning strikes is provided by using lightning arresters. Lightning arrester is a device that is elevated over the protected facility through which the lightning current goes into the ground bypassing the protected facility. It consists of a lightning rod that directly accepts the discharge of a lightning , a current collector, and a grounding electrode.EIC Rev. 7, item 1.7.103, total dissipation resistance of ground terminals (including natural ones) of all repeated groundings of the PEN wire of each high-voltage line in any season of the year should not exceed 10 Ohm, respectively, with linear voltages 380 V of a three-phase source or 220 V of a single-phase source.
A set of measures to meet the necessary requirements to the lightning protection and grounding systems includes the following solutions:
- Installation of one 10 m lightning rod at the distance of 3 m from the facility (see Fig. 2);
- Installation of a grounding arrangement, comprising 5 x 2 m vertical electrodes combined with a horizontal electrode (copper-plated strip 30 x 4 mm). The distance between the vertical electrodes is at least 5 meters, the distance from the electrode to the foundation of the charging station is at least 1 m, the depth is 0.5 to 0.7 meter.
Ground terminal resistance calculation:
Верт - Vert
Ом - Ohm
Гор - Hor
ЗУ - GA
The calculated resistance of the grounding arrangement is 5,41 Ohm which is less than allowed resistance of 10 Ohm.
The occurrence of lightning strikes into the ground is 4 strikes/sq. km per year;
The total number of strikes into the system is 0.013 (once every 77 years);
The total number of blowouts is 0.00019 (once per 5,263 years);
The system's reliability is 0.985;
The probability of breakout into all facilities of the system is 0.015.
The results of calculation of protection zones according to SO:
Lightning mast No. 1 (ZZ-201-010):
h = 10 m;
Cone height according to SO, Table 3.4:
- Молниеприемник – мачта высотой 10 м - 10 m lightning mast
- Полоса омедненная стальная сечением 30х4 мм - Steel copper-plated bar 30 x 4 mm
- Электрод D=14 мм, L =3 м. - Electrode D = 14 mm, L = 3 m.
Cone radius according to SO, Table 3.4:
Direct lightning strike protection zone is shown in Fig. 2.
Lightning mast is a 10 m high mast - air terminal mast 10 m high; copper-bonded steel tape with the cross-section of 30 x 4 mm; Electrode D = 14 mm, L= 3 m.
Figure 2. Equipment layout. Protection zone
The list of necessary materials is given in Table 1.
Table 1. List of needed materials.
|Item #||Fig.||Part number||Product||Quantity, pcs|
|1.||ZZ-201-010||ZANDZ 10 m vertical lightning rod (galvanized steel; with parts embedded under the foundation)||1|
|2.||ZZ-001-065||ZANDZ Copper-plated threaded grounding rod (D14; 1.5 m)||10|
|3.||ZZ-002-061||ZANDZ Threaded connecting coupling||6|
|4.||ZZ-003-061||ZANDZ Takeoff Tip||5|
|5.||ZZ-004-060||ZANDZ Guide head for jackhammer attachment||2|
|6.||ZZ-006-000||ZANDZ Conductive grease||1|
|7.||ZZ-008-000||ZANDZ Attachment to the jackhammer (SDS max)||1|
|9.||GL-11075-20||GALMAR Copper-plated bar (30 * 4 mm / S 120 mm²; bundle 20 meters)||2|
Installation of a standalone 10 m lightning rod provides the lightning protection reliability for Category II which is, in turn, a good indicator, and reduces the lightning breakthroughs number to once in 5,263 years.
The use of copper-plated grounding arrangements as a circuit along the facility perimeter with vertical electrodes will allow providing a reliable grounding for the electrical installation for at least 30 years!
Use professional solutions together with ZANDZ!
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