The ZANDZ Technical Center regularly receives requests for the calculation of interesting and specific objects. There are very remarkable objects among them, that we cannot help but share them with you. A thermal webcam, located on the top of Elbrus is one of such objects.
View on Elbrus (image taken from the site www.wikipedia.org)
Everyone knows that the tops of the mountains are most frequently exposed to lightning strikes. Therefore, placing a camera in such conditions, it is necessary to provide serious measures on lightning protection and grounding. The project offered a non-standard design accepting the lightning, which must eliminate a direct strike directly into the equipment and divert the lightning to the ground. At a very close path of the lightning current to the equipment and electrical circuits, the impact of overvoltages is obvious. It is possible to protect from them only with the help of the SPD and shielded cables. Therefore, devices against overvoltages, which must be installed inside the thermobox in all electrical circuits and transmission circuits interconnecting the chambers, solar panels, injector, controller and transmitter were offered.
The operation of external and internal lightning protection systems is impossible without a grounding device. Under the conditions of rocky soil, electrolytic grounding should be applied. It will serve as a good protective and functional grounding, which will provide operation of chambers without interferences.
All the offered solutions for lightning protection and grounding of a WEB-camera are studied below.
A thermal vision webcam on the top of Elbrus is an object of installation of grounding.
The activities were carried out in accordance with the EIC 7 th ed. Chapter 1.7
The soil at the location place of the object is rocky with loose rocks and ice, the calculated resistivity is taken equal to 2000 Ohm ∙ m.
In accordance with the EIC 7th ed. n. 1.7.103 the total resistance of spreading of ground electrodes (including natural) of all the repeated groundings of the PEN conductor at any time of the year should be not more than 10 ohms, respectively, with line voltages of 380 V of a three-phase power supply or 220 V of a single-phase power source.
In accordance with the EIC p. 1.7.103 at the specific soil resistance ρ > 100 Ohm • m , it is allowed to increase the indicated norms in 0.01 ρ times, but not more than tenfold.
The set of measures to ensure the necessary requirements to the grounding device is represented by the following solutions:
- To ensure the rated resistance of a grounding device, electrolytic grounding ZANDZ ZZ-100-102 specially designed for use in rocky and permafrost soils is offered for use.
- Installation of one kit of electrolytic grounding ZANDZ ZZ-100-102 is carried out;
- A horizontal ground electrode made of stainless steel copper-bonded tape with the cross-section 4x30 mm 4-10 m is run to the site.
- In connection with the formation of talik zone in the form of an oval 3x6 meters in size, the electrodes must be placed at an appropriate distance from the foundations of buildings and other engineering structures.
Figure 1 - Sketch of lightning protection and grounding devices elements
Условные обозначения: notations
Комплект ZZ-100-102 - ZZ-100-102 kit
Горизонтальный электрод – horizontal electrode
Зажим для подключения проводника – clamp for connecting conductor
Calculation of grounding device resistance:
The horizontal ground electrode is not involved in the calculation, only the kit of electrolytic grounding is considered.
Resistance of ZZ-100-102 kit
where C - non- dimensional factor, describing the electrolyte content in the surrounding soil;
ρ - soil resistivity, ohm-m;
L - length of ground electrode, m;
d - diameter of ground electrode, m;
T - deepening - distance from ground surface to the ground electrode, m
Impedance of the grounding device:
Where n - number of kits;
kисп - coefficient of use;
The design resistance of the grounding device is 84.14 ohms, which is less than the desired resistance of 100 ohms, obtained by increasing the rate of 10 ohms 10 times.
A complex of measures on the organization of lightning protection system is represented by the following solutions:
- It is necessary to install a lightning rod, which is shown in Figure 1.
- The cables should be shielded. When transmitting power and data over the twisted pair, the following cables should be used: SSTP, SFTP, STP, PiMF.
Surge protection:
- In order to protect the line from the photovoltaic panels, SPDs for the DC link with the voltage of 80 V LE-278-080 DataPro2x1-80V / 80V are used.
- To protect the power line with the voltage of 24 V, SPD LE-272-424 DataPro2x1-24V / 24V is used.
Figure 2 - Electronic circuit DataPro2x1-80V / 80V and DataPro2x1-24V / 24V
- To protect the camera, SPD LE-240-021 DataPro RJ45 PoE Alu, installed in series of a shielded twisted pair cable is used.
Figure 3 - Electronic circuit DataPro RJ45 PoE Alu
- In order to protect the data line going to the transmitter, an interchangeable SPD unit LE-970-041 MP 2x2 GDT+24V-Ad-Ad-Pg ST is used, if the signal frequency is up to 6 MHz. Or SPD for high-frequency lines LE-971-051 MP 2x2 24V-HF ST, if the signal frequency is up to 70 MHz. The base part LE-970-001 MP Base 2x2-R GDT is used for an interchangeable unit.
Figure 4 - Electronic circuit MP 2x2 GDT +24V-Ad-Ad-Pg ST
Figure 5 - Electronic circuit MP 2x2 24V-HF ST
Important! All the SPDs should be installed directly at the input of a thermobox, the cable length should not exceed 0.5 m and should be minimized.
The thermobox should be shielded, for example with the help of foil.
The list of required material is given in Table 1.
Table 1 – The list of materials demand
| № | Fig. | Product item | Product | Quantity |
| 1. |  |
ZZ-100-102 | ZANDZ Electrolytic grounding kit (horizontal; 3 m) | 1 |
| 2. | .jpg) |
GL-11075-20 | GALMAR copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 20 meters) | 1 |
| 3. | .jpg) |
ZZ-005-064 | ZaNDZ Clamp for conductor's connection (up to 40 mm) |
2 |
| 4. | .jpg) |
ZZ-007-030 | ZANDZ Waterproof tape | 1 |
| 5. |  |
LE-278-080 | LEUTRON surge arrester (SPD) DataPro2x1-80V / 80V | 1 |
| 6. | LE-272-424 | LEUTRON surge arrester (SPD) DataPro2x1-24V / 24V | 1 | |
| 7. |  |
LE-240-021 | LEUTRON surge arrester (SPD) DataPro RJ45 PoE Alu | 1 |
| 8. |  |
LE-970-041 | LEUTRON surge arrester (SPD) MP 2x2 GDT +24V-Ad-Ad-Pg ST | 1 |
| 9. |  |
LE-970-001 | LEUTRON MP Base 2x2-R GDT | 1 |
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