The ZANDZ Technical Center has received a request to calculate the lightning protection system for a chemical analysis laboratory located in the European part of Russia. Let's consider the solution offered by our specialists.
Calculation data:
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Facility: chemical analysis laboratory.
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Facility drawing.
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Soil resistivity: 100 Ohm*m.
Задача:
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calculate the lightning protection system;
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calculate the grounding arrangement.
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 referred to as RD.
The facility is "special, environmentally hazardous" from the viewpoint of SO and is classified as Category I of the lightning protection according to RD.
A set of measures to provide the necessary requirements to the lightning protection system and to the grounding arrangement for the chemical analysis laboratory includes the following solutions:
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The lightning protection is made using 16 m lightning masts (ZZ-201-016-B7-Sn5-S9). The lightning arresters are installed on concrete foundations. The distance to the facility is at least 3 m.
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The protection zone should include space over the valves, r = 5 m; h = 2.5 m.
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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 = 16 m;
Cone height according to SO, Table 3.4:
м - m
Cone radius according to SO, Table 3.4:
м - m
The distance (maximum) between lightning arresters:
L = 22 m;
Limit distance between lightning arresters according to SO, Table 3.6:
м - m
There is not sagging height.
For the protection zone with the required reliability, radius rx at the height of h0 = 7.5 m is defined as:
м - m
Ground terminal resistance calculation:
Vertical electrode resistance:
Ом - Ohm
where ρeq is equivalent soil resistivity, 100 Ohm·m;
L is vertical electrode length, 3 m;
d is diameter of the vertical electrode, 0.014 m;
T is deepening, i.e. the distance from the ground surface to the ground electrode, 2 m;
where t is deepening of the electrode top, 0.5 m.
Horizontal electrode resistance:
Ом - Ohm
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, 79 m.
Electrical impedance of the grounding arrangement:
Ом - Ohm
where n is a number of sets, vertical grounding arrangements - 7 pcs, horizontal grounding arrangement - 1 pc;
Kutil is utilization rate, 0.69.
The rated resistance of the grounding arrangement is 2,51 Ohm.
The equipment layout and the protection zone are shown in Fig. 1.
Условные обозначения - Key
Молниеприемник-мачта высотой 16 м - Lightning arrester, 16 m high
Полоса стальная оцинкованная сечением 30х4 мм - Steel zinc-plated bar with cross-section 30 x 4 mm
Зажим для подключения проводов - Clamp for connecting wires
Вертикальный заземлитель длиной 3 м - Vertical grounding electrode, 3 m long
Зона защиты h = 7,5 м - Protection zone h = 7.5 m
Защищенное пространство над клапанами r=5 м; h=2,5 м - Protected space above valves, r = 5 m; h = 2.5 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-201-016-В7-Сн5-С9 | ZANDZ Lightning arrester, vertical, 16 m (zinc-plated steel; with embedded elements for the foundation; 7th wind region; 5th snow region; 9th seismic region) | 4 | ||
| GROUNDING ARRANGEMENT: | |||||
| 2. | GL-11075-50 | GALMAR Copper-plated strip (30 * 4 mm / S 120 mm²; 50-meter strip bundle) | 1 | 0,98 | Вес за 1 м |
| 3. | GL-11075-20 | GALMAR Copper-plated bar (30 * 4 mm / S 120 mm²; bundle 20 meters) | 2 | 0,98 | Вез за 1 м |
| 4. | ZZ-001-065 | ZANDZ Copper-plated threaded grounding pin (D14; 1.5 m) | 14 | 2,00 | |
| 5. | ZZ-002-061 | ZANDZ Threaded coupling | 8 | 0,08 | |
| 6. | ZZ-003-061 | ZANDZ Takeoff tip | 7 | 0,07 | |
| 7. | ZZ-004-060 | ZANDZ Guide head for jackhammer attachment | 3 | 0,09 | |
| 8. | ZZ-005-064 | ZANDZ Conductor connection terminal (up to 40 mm) | 15 | 0,312 | |
| 9. | ZZ-006-000 | ZANDZ Conductive grease | 1 | 0,10 | |
| 10. | ZZ-007-030 | ZANDZ Waterproofing tape | 5 | 0,40 | |
| 11. | ZZ-008-000 | ZANDZ Attachment to the hammer (SDS max) | 1 | 0,50 | |
Do you have any questions regarding lightning protection and grounding for the chemical analysis laboratory? Please contact the ZANDZ Technical Center!
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