Heliograph allows observing the structure and dynamics of the sources of microwave radiation in the solar atmosphere. Special requirements are applied to such equipment, and they are described in the terms of reference. It is important to provide lightning protection and grounding system for the facility. The ZANDZ Technical Center has received a request to calculate the lightning protection for the heliograph. Let us continue with more detailed review of our offered solution.
Calculation of the heliograph lightning protection
Figure 1. Facility plan.
Task: to perform calculations for the lightning protection system for a heliograph.
Solutions to fulfil the requirements for the lightning protection system for the heliograph:
- The lightning protection is made in accordance with the Electrical Installations Code (EIC), Rev. 7, SO 153-34.21.122-2003 "Guidelines for the lightning protection of buildings, structures and industrial infrastructure" (hereinafter referred to as SO) and RD 34.21.122-87 "Guidelines for the lightning protection of buildings and structures" (hereinafter referred to as the RD).
- The system reliability should be at least 0.98.
- The facility's lightning protection is made using 36 x 11 m wire lightning arresters (ZZ-204-110), with wire installation height being equal to 10 m.
- For each lighting arrester, a grounding arrangement is installed as follows:
- Laying the horizontal grounding device for the current flowing in two directions. Length of each ground electrode is 5 m. The ground electrode is made of a corrosion-resistant steel copper-plated strip with a cross-section of 4 x 30 mm (GL-11075), the laying depth is 0.5 m.
- At the end of the horizontal ground electrode, one vertical electrode with the length of 3 m is installed in each direction.
- Vertical and horizontal electrodes, as well as horizontal electrodes with the interception rod are connected using clamps ZZ-005-064.
- The grounding arrangement for item 3.1 was made using 7 sets of electrolytic grounding ZZ-100-102. Grounding electrodes are installed with the step at least 6 x 9 m. The sets are connected together using copper-clad steel wire with a cross-section of 30x4 mm. The distance from the electrodes to communications and foundations should be no less than 3 m. The embedment is 0.6 m.
- The grounding arrangement for item 3.2 was made using a steel copper-plated bar 30 x 4 mm along the tunnel.
The results of calculation performed using the software developed by the Krzhizhanovsky Energy Institute (OAO ENIN):
density of lightning strikes into the ground is 4 strikes/sq. km per year.
Total number of strikes into the system is 0.57 (once every 2 years).
The total number of breakouts into the system is 0.0040 (once every 250 years).
The probability of a blowout into the system's facilities is 0.0070.
The system reliability is 0,993.
Ground terminal resistance calculation:
Гор - Hor
Ом - Ohm
ЗУ - GA
The calculated resistance of the grounding arrangement is 7,39 Ohms.
Figure 2 shows hardware layout.
Table 1 includes the list of required hardware and materials.
Условные обозначения - Legend
Figure 2. Layout of hardware for the lightning protection of a heliograph.
Table 1. List of material requirements.
Do you have any questions about lightning protection of the heliograph or other facilities? Please, contact the ZANDZ Technical Center!