The ZANDZ Technical Center has received a request to calculate the lightning protection system for a solar power plant. Let us further consider a solution proposed by our specialists.
Initial data:
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facility: solar power plant;
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dimensions: 120 m x 102 m x 2 m;
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Soil resistivity: 100 Ohm*m.
Task:
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calculate the lightning protection system;
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calculate the grounding device.
Solution:
Lightning protection and grounding of the building are made in accordance with:
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SO 153 34.21.122 2003 "INSTRUCTIONS FOR MOUNTING LIGHTING PROTECTIONS OF BUILDINGS, STRUCTURES AND INDUSTRIAL COMMUNICATIONS", hereinafter referred to as SO;
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RD 34.21.122 87 "INSTRUCTIONS FOR MOUNTING LIGHTING PROTECTION OF BUILDINGS AND STRUCTURES",hereinafter to as RD/
The facility is classified as “conventional” from the viewpoint of SO and as Category III of the lightning protection according to RD.
A set of measures to provide necessary requirements to the lightning protection system and to the grounding arrangement for the solar power plant includes the following solutions:
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10 m lightning arresters located along the perimeter of the protected area are used as lightning arresters to protect the area.
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Copper-plated steel electrodes 3 m long are used as a vertical grounding arrangement.
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The copper-plated steel strip with a cross-section of 30 x 4 mm, combining all vertical electrodes, is used as a horizontal ground electrode. The distance to the mast foundation is at least 1 m. Strip deepening is 0.5 to 0.7 m.
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Connection to the grounding arrangement is made through clamps ZZ-005-064.
The results of calculation of protection zones according to SO:
h = 10 m;
Cone height according to SO, Table 3.4:
h0 = 0,85*h = 8,5 m;
Cone radius according to SO, Table 3.4:
r0 = 1,2*h = 12 m;
For the protection zone with the required reliability, radius rx at the height of h0 = 2 m is defined as:
М - m
Distance between the lightning arresters (maximum):
L = 38 m;
Limit distance between lightning arresters according to SO, Table 3.6:
Sagging height:
For the protection zone with the required reliability, radius rcx at height h0 = 2 m is defined as follows:
Ground terminal resistance calculation:
Vertical electrode resistance:
Ом - Ohm
Верт - Vert
Экв - Eq
where ρρeq is equivalent soil resistivity, 100 Ohm·m;
L – is vertical electrode length, 3 m;
d – is vertical electrode diameter, 0.014 m;
T – deepening - is the distance from the ground surface to the ground electrode, 2 m;
where t – is deepening of the top of the electrode, 0.5 m.
Horizontal electrode resistance:
Ом - Ohm
Гор - Hor
where ρ – is soil resistivity, 100 Ohm·m;
b - is horizontal electrode width, 0.03 m;
h - is horizontal electrode depth, 0.7 m;
Lhor - is horizontal electrode length, 1,160 m.
Electrical impedance of the grounding arrangement:
Ом - Ohm
ЗУ - GA
where n – is a number of sets, vertical grounding arrangements - 11 pcs, horizontal grounding arrangement - 1 pc;
Kutil is utilization rate, 0.63.
The calculated resistance of the grounding arrangement is 0,38 Ohm.
The location of the equipment is shown in Figure 1
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Условные обозначения - Legend
- молниеприемник-мачта высотой 10 м - 10 m lightning rod
- полоса стальная оцинкованная сечением 30х4 мм - steel zinc-plated bar with cross-section 30 x 4 mm
- зажим для подключения проводника - clamp for connecting conductor
- вертикальный заземлитель длиной 3 м - 3 m vertical grounding electrode
- зона защиты на высоте 2 м - protection zone at the height 2 m
Figure 1. Equipment layout.
The list of necessary materials is given in Table 1.
Table 1. List of needed materials.
| № | Part number | Name | Quantity, pcs. | Unit weight, kg | Note |
| LIGHTNING PROTECTION: | |||||
| 1. | ZZ-201-010 | ZANDZ 10 m vertical lightning arrester (zinc-plated steel; with parts embedded under the foundation) | 1 | ||
| GROUNDING ARRANGEMENT: | |||||
| 2. | GL-11075-50 | GALMAR Copper-plated strip (30 * 4 mm / S 120 mm²; 50-meter strip bundle) | 26 | 0,98 | Вес за метр |
| 3. | ZZ-001-065 | ZANDZ Copper-plated threaded grounding rod (D14; 1,5 m) | 22 | 2,00 | |
| 4. | ZZ-002-061 | ZANDZ Threaded coupling | 12 | 0,08 | |
| 5. | ZZ-003-061 | ZANDZ Termination | 11 | 0,07 | |
| 6. | ZZ-004-060 | ZANDZ Guide head for jackhammer attachment | 5 | 0,09 | |
| 7. | ZZ-005-064 | ZANDZ Conductor connection terminal (up to 40 mm) | 106 | 0,312 | |
| 8. | ZZ-006-000 | ZANDZ Conductive grease | 2 | 0,10 | |
| 9. | ZZ-007-030 | ZANDZ Waterproofing tape | 36 | 0,40 | |
| 10. | ZZ-008-000 | ZANDZ Attachment to the hammer (SDS max) | 1 | 0,50 | |
Do you have any questions regarding lightning protection and grounding of the solar power plant? Please contact the ZANDZ Technical Center.
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