The ZANDZ Technical Center has received a request to calculate the lightning protection and grounding system for the cheese factory in the Ryazan Region. Let's further consider the solution.
Initial data:
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facility: cheese factory;
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dimensions: 30.4 mm x 52 m;
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height: 10 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 referred to as RD./
The facility is classified as conventional in terms of SO and to Category III of lightning protection according to RD. The required reliability of the lightning protection system shall be at least 0.9.
A set of measures to meet the necessary requirements to the lightning protection system and to the grounding arrangement of the cheese factory includes the following solutions:
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The facility lightning protection is made using 4 m lightning arresters (ZZ-201-004). The masts are secured to the facade using brackets.
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A steel copper-plated wire d8 mm (GL-11149) is used as a lightning arrester.
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Current collectors are installed using clamps GL-11711 on the roof and GL-11703A on vertical surfaces. The clamp installation spacing is 0.8 to 1.0 m.
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The current collector downdrops are made along the waterspouts.
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The universal GL 11551A clamp is used to connect the rolled products over the length and in assemblies.
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All metal elements located on the roof shall be connected to the down conductor using GL 11545A clamps. Stairs, railings, are attached using the GL 11514N ring clamp.
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Copper-plated steel electrodes 3 m long in the locations of the current collector downdrops are used as vertical ground electrodes.
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The copper-plated steel strip with a cross-section of 30 x 4 mm, interconnecting all vertical electrodes, is used as a horizontal ground electrode. The distance to the facility foundation is at least 1 m. Strip deepening is 0.5 to 0.7 m.
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According to EIC-7 issue, par.1.7.55, Grounding devices for protective grounding of electrical installations for buildings and structures and Categories 2 and 3 of lightning protection of these buildings and structures, as a rule, shall be common.
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If there are concrete-steel constructions, they shall be connected to down conductors/grounding device.
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Connection to the grounding device is carried out using ZZ-005-064 clamps.
Calculation results carried out using software developed by the G.M. Krzhizhanovsky Energy Institute, JSC ENIN
The occurrence of lightning strokes into the ground is 4 strokes/sq. km per year
The total number of strikes into the system is 0.049 (once every 20 years).
The total number of breakouts into the system is 0.0021 (once every 476 years).
The system reliability is 0.957;
The probability of breakout into all facilities of the system is 0.043.
Ground terminal resistance calculation:
Vertical electrode resistance:
Верт - Vert
Экв - Eq
Ом - Ohm
where ρeq is equivalent soil resistivity, 100 Ohm·m;
L is vertical electrode length, 3 m;
d is vertical electrode diameter, 0.014 m;
T is depth, i.e. the distance from the ground surface to the ground electrode, 2 m;
м - m
where t is deepening of the top of the electrode, 0.5 m.
Horizontal electrode resistance:
Гор - Hor
Ом - Ohm
where ρ is soil resistivity, 100 Ohm·m;
b is horizontal electrode width, 0.03 m;
h is horizontal electrode depth, 0.5 m;
Lгор is horizontal electrode length, 32 m.
Electrical impedance of the grounding arrangement:
ЗУ - GA
Ом - Ohm
where n is a number of sets, vertical grounding arrangements - 2 pcs, horizontal grounding arrangement - 1 pc;
Kutil is utilization rate, 0.81.
The rated resistance of the grounding device is 5.29 Ohms.
The location of the equipment is shown in Figure 1.
Условные обозначения - Legend
- молниеприемник-мачта высотой 4 м - 4 m lightning arrester
- проволока стальная омедненная диаметром 8 мм - steel copper-plated wire 8 mm
- полоса стальная омедненная сечением 30х4 мм - steel copper-plated bar 30 x 4 mm
- зажим для подключения проводника - wire connection clamp
- опуск токоотвода - downdrop
- вертикальный заземлитель длиной 3 м - 3 m vertical grounding electrode
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 |
| 1. | ZZ-201-004 | ZANDZ Tower interception rod, 4 m (stainless steel) | 8 | 8,50 | |
| 2. | ZZ-203-001 | ZANDZ Wall fastening for interception rod (stainless steel) | 8 | 14,665 | |
| 3. | ZZ-202-001 | ZANDZ Interception rod terminal for main conductor cables (stainless steel) | 8 | 0,20 | |
| 4. | GL-11149-50 | GALMAR Copper-plated wire (D 8 mm/S 50 mm²; 50-meter bundle) | 5 | 0,41 | Вес 1 м |
| 5. | GL-11551A | GALMAR Conductor connection clamp (painted zinc-plated steel) | 20 | 0,07 | |
| 6. | GL-11711 | GALMAR Flat roof terminal for the conductor cable (plastic, concrete) | 50 | 1,20 | |
| 7. | GL-11703A | GALMAR Current collector facade clamp providing 15 mm elevation of the collector over the clamp (painted zinc-plated steel) | 220 | 0,02 | |
| 8. | GL-11075-20 | GALMAR Copper-plated bar (30 * 4 mm / S 120 mm²; bundle 20 meters) | 2 | 0,98 | Вес 1 м |
| 9. | ZZ-001-065 | ZANDZ Copper-plated threaded grounding rod (D14; 1,5 m) | 4 | 2,00 | |
| 10. | ZZ-002-061 | ZANDZ Threaded coupling | 3 | 0,08 | |
| 11. | ZZ-003-061 | ZANDZ Termination | 2 | 0,07 | |
| 12. | ZZ-004-060 | ZANDZ Guide head for jackhammer attachment | 1 | 0,09 | |
| 13. | ZZ-005-064 | ZANDZ Conductor connection terminal (up to 40 mm) | 6 | 0,312 | |
| 14. | ZZ-006-000 | ZANDZ Conductive grease | 1 | 0,10 | |
| 15. | ZZ-007-030 | ZANDZ Waterproofing tape | 2 | 0,40 | |
| 16. | 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 cheese factory? Please contact the ZANDZ Technical Center!
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