July 28, 2017
Safety of industrial enterprises, warehouses, offices, single-family houses and many other facilities depends on the CCTV systems' reliability. What factors affect the stability of such systems? Power quality and electromagnetic environment in the location where CCTV cameras are installed are not least of all. In other words, to provide their seamless operation, we need:
- Internal and external lightning protection systems;
- Grounding system.
CCTV cameras are frequently installed on light towers. In these cases, there is often no need in the external lightning protection for CCTV. However, protection against secondary effects of the lightning strike is mandatory, i.e. internal lightning protection system. It includes surge protection devices (SDPs) for main power and control circuits.
Moreover, precise electronic equipment responsible for video signal transfer and processing requires high-quality grounding. The ZANDZ Technical Center has recently received a request to calculate it and select SDPs for the CCTV systems. Let's study how this task has been solved by our engineers.
Initial data:
- A single-phase power circuit 220 V;
- Soil resistivity of 100 Ohm*m (soil power is 3 m);
- No area limitations;
- The video camera includes SDP up to 6 kV for data line protection.
Tasks to arrange grounding and lightning protection for a grounding system:
- To calculate the grounding arrangement having resistance not more than 4 Ohm;
- Select an SDP to protect main power circuits.
Solution:
- Installation of a grounding arrangement consisting of 50 m of steel copper-plated bar with the cross-section of 30 x 4 mm. Depth is 0.7 meter;
- To provide protection of the main power circuit against pulse surge, Class 1+2+3 SDPs LEUTRON PP BCD TN 25/50 are used.
Ground terminal resistance calculation:
Гор - Hor
Ом - Ohm
Estimate resistance of the grounding arrangement is 3,94 Ohm, which is less than the required value of 4 Ohm.
Design of the grounding arrangement for the CCTV system
Figure 1. CCTV Grounding Elements Layout.
Copper bonded steel tape with the cross-section 30 x 4 mm
ОБЪЕКТ - FACILITY
The list of necessary materials is given in Table 1.
Table 1 – List of material requirements.
| № | Figure | Part number | Name | Quantity, pcs. |
| 1. |  |
ZZ-005-064 | ZANDZ Conductor connection clamp (up to 40 mm) | 4 |
| 2. |  |
ZZ-007-030 | ZANDZ Waterproofing tape | 1 |
| 3. |  |
GL-11075-50 | GALMAR Copper-plated strip (30 * 4 mm / S 120 mm²; 50-meter strip bundle) | 1 |
| 4. |  |
LE-381-214 | LEUTRON Surge Protection Device (SPD) PP BCD TNS 25/50 | 1 |
Depending on the CCTV configuration, specifics of its installation and the area available for grounding, the number and composition of protection elements may vary. To learn more about grounding and lightning protection of the CCTV systems and get an assistance in calculations, contact the ZANDZ Technical Center!
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