There are several ways to protect a water pumping station and the material assets that are in it from lightning. One of the easiest is to use metal tanks as natural lightning rods. There are buildings in the territory that require artificial lightning protection, and equipment that must be protected with the help of an SPD. It was just such a case that the ZANDZ Technical Center faced in one of its recent projects. We will study the solutuon we offered in detail.
Calculation of lightning protection of a water pumping station
Object: water pumping station.
Figure 1 - Object plan.
Task: Perform calculations of the lightning protection system of the pumping station.
Protection of buildings and structures against lightning discharges is ensured by lightning rods. A lightning rod is a device rising above the facility that diverts lightning current into the ground without entering the facility. It consists of a lightning rod which directly takes the lightning discharge upon itself, a down conductor and a ground electrode.
Solutions to meet the requirements for a lightning protection system of a water pumping station:
1. Lightning protection is carried out in accordance with EIC 7th edition., IS 153-34.21.122-2003 "Instructions for lightning protection of buildings, structures and industrial communications" (hereinafter IS) and AD 34.21.122-87 "Instructions for lightning protection of buildings and structures" (hereinafter AD).
2. The object refers to category 3 of lightning protection. System reliability must be not less than 0,9.
3. In the calculation we use objects that are nearby, namely tanks.
4. In addition, we install 1 vertical air terminal mast 4 m high on 3 concrete bases on the building of the water pumping station (GL-21121).
5. Connecting down conductors to the lightning rod and its downdrop to the grounding device.
6. To connect rolled metal over the length a universal clamp GL-11551A is used.
7. All metal structures and communications must be connected to the down conductor using clamps GL-11545A, stairs, railings, are connected using clamp GL-11514.
8. Installation of a grounding device consisting of 4 vertical electrodes of 3 m in length united by a horizontal electrode (a copper-bonded tape of 30x4 mm). The distance from the horizontal electrode to the object should be not less than 1 m, deepening 0.5 - 0.7 meters.
9. In case of presence of the existing grounding device, they should be united into one grounding device in accordance with EIC p.1.7.55.
10. For the protection of video surveillance equipment, an SPD (LE-240-021) is provided.
Results of the calculation carried out with the software developed by the OJSC "Energy Institute to the name of G.M. Krzhizhanovsky (JSC "ENIN"):
Density of lightning strikes into the ground - 4 strikes / sq. km per year;
Full number of strikes into the system – 0.034 (once in 29 years);
The total number of breakthroughs is 0.0035 (every 286 years);
System reliability — 0.9;
Probability of breakthrough into all the system objects - 0.10.
Grounding device resistance calculation:
The design resistance of the grounding device is 3.4 ohms.
Figure 2 shows the arrangement of equipment.
Table 1 gives the list of the required equipment and materials.
Figure 2 - Location of equipment for lightning protection of the water pumping station.
Table 1 - List of need in materials.
Do you have any questions about lightning protection of pumping stations or other facilities? Please contact our ZANDZ Technical center!