# HOW TO CALCULATE TECHNOLOGICAL GROUNDING: WE ARE CONSIDERING A REAL EXAMPLE

Technological grounding is required for the correct operation of electronic equipment. At customs points, a thorough inspection of goods is carried out, for this different electronic appliances are used.

ZANDZ Technical Center designed technological grounding for the needs of customs, according to one of the incoming requests. Consider this solution further.

Initial data:

• soil resistivity is 200 Ohms*m;
• make technological grounding from the facility at a distance of at least 20 m from the grounding contour of the facility.

Calculate technological grounding for customs with the resistance of 4 ohms max.

A set of measures to provide the necessary requirements for the technological grounding unit of the customs is represented by the following solutions:

1. Technological grounding consists of 12 vertical earthing switches made of copper-plated steel, 6 m long, united by a copper-plated steel strip of 30x4 mm (GL-11075). The distance between the electrodes is 6 m min, deepening is 0.5 m min.

2. The distance between protective and technological grounding devices is 20 m min. At points of intersection, it is necessary to isolate them from each other. Potential equalization is carried out on the MGB (Main Grounding Bus).

3. Fastening of the strip to the ceilings/walls is carried out using holders GL-11751A.

4. Connection to the grounding device is carried out using ZZ-005-064.

5. Technological grounding must be connected to the grounding bus, which is mounted in the switchboard room and to connect it to the MGB, as part of the potential equalization system.

Ground terminal resistance calculation:

Vertical electrode resistance:

where рэкв - is soil equivalent resistivity, 200 Ohms m.

L - is vertical electrode length, 6 m;

d - is the diameter of the vertical electrode, 0.014 m;

T - is the distance from the ground surface to the ground electrode, 3.5 m;

Horizontal electrode resistance:

where р - is soil resistivity, 200 Ohms m;

b - is horizontal electrode width, 0.03 m;

h - is the depth of the horizontal electrode, 0.5 m;

Lгор - is horizontal electrode length, 66 m.

where t - is deepening of the top of the electrode, 0.5 m

Grounding impedance:

where n - is number of sets, 12 pcs. (vertical ground electrode), 1 pcs. (horizontal ground electrode);

Kисп - is utilization rate, 0.55.

Rated resistance of the grounding device is 3,87 ohms, which is less than the required value of 4 ohms.

The location of the equipment is shown in Figure 1.

Объект - Facility
Защитное заземление и заземление молниезащиты - Protective grounding and lightning protection grounding
Изолировать технологическое заземление от защитного - Isolate technological grounding from protective grounding
Условные обозначения - Conventional symbols
Полоса стальная оцинкованная сечением 40х4 мм (GL-11075) - Galvanized steel strip with a section of 40x4 mm (GL 11075)
Зажим для подключения проводника (ZZ-005-064) - Main conductor connection terminal (ZZ-005-064)
Вертикальный заземлитель длиной 6 м - Vertical ground electrode, 6 m. long

Figure 1 - equipment location.

The list of necessary materials is given in Table 1.

Table 1 - List of needed materials.

 № Part number Description Quantity, pcs. Weight, kg Note 1. GL-11075-50 Copper-plated strip GALMAR (30*4 mm / S 120 mm²; 50-meter coil) 10 0,98 В бухтах 2. ZZ-001-065 ZANDZ Copper-plated threaded earthing rod (D14; 1,5 m) 48 2,00 3. ZZ-002-061 ZANDZ Threaded coupling 37 0,08 4. ZZ-003-061 ZANDZ Termination 12 0,07 5. ZZ-004-060 ZANDZ Demolition hammer guide head 10 0,09 6. ZZ-005-064 ZANDZ Conductor connection terminal (up to 40 mm) 29 0,158 7. ZZ-006-000 ZANDZ Current-conducting lubricant 4 0,10 8. ZZ-007-030 ZANDZ Waterproofing tape 4 0,40 9. ZZ-008-000 ZANDZ Demolition hammer head (SDS max) 1 0,50 10. GL-11751A GALMAR Clamp to the facade/wall for flat down conductor (down conductor 30*4mm; galvanized painted steel) 50 0,04

Do you have questions or do you need to calculate the technological grounding for the needs of customs? Send a request to info@zandz.ru.

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