How to achieve low resistance of functional grounding in the conditions of shortage of space?

Functional grounding

Organizing a functional (working) grounding with low resistance is much more difficult than, say, grounding of a single-family house at 30 ohms. To solve the first problem a large area is required, which we will have to literally pave with ground electrodes. In Figure 1 - a typical example of a working grounding: a grid with the dimensions of 40x60 m and 12 vertical electrodes with the length of 15 m at its joints. If we use vertical electrodes of shorter length, then the ground electrode will occupy even more space.

Figure 1 - For traditional functional grounding, a large area and multiple electrodes are needed.

But what to do when free space is limited? It happens so that in the conditions of dense urban development, there is only a narrow strip 25 meters long along one wall of the building that can be used for grounding, instead of a territory around the building. That was this space that the customer allocated for the installation of functional grounding with the resistance of up to 1 Ohm, when he addressed to the ZANDZ Technical Center. EZANDZ electrolytic grounding comes to the rescue the designers in such complicated cases. We will study the solution offered to the customer in more detail.

Solution

The requirements to the grounding device are satisfied by the following solutions:

• to ensure the normalized resistance of the grounding device it is offered to use electrolytic grounding ZANDZ ZZ-100-102-9MB;
• installation of five vertical electrolytic grounding sets with a length of 9 meters ZANDZ ZZ 100 102-9MB. They are united with a horizontal grounding conductor made of a corrosion-resistant steel copper-bonded tape with a section of 4x30 mm (GL-11075);
• The kits are installed at the distance of at least 6 meters at the parallel installation. This ensures an acceptable utilization rate and an optimal amount of electrolyte distribution in the soil;
• The connection of ground electrodes s is made with the clamps ZZ-005-064. To connect the tape in length two clips ZZ-005-064 are laid.

Figure 2 - ZANDZ electrolytic grounding kits provide an opportunity to organize a functional grounding with low resistance in a confined space.

Условные обозначения - notations
Комплект электролитического заземления – electrolytic grounding kit
Зажим для подключения проводника – conductor connecting clamp

Calculation of a grounding device resistance:

Upon the request of the customer, the design specific resistivity of the soil is assumed to be 120 Ohm m.

Resistance of ZZ-100-102-9MB kit:

where Ca non-dimensional factor describing the electrolyte content in the surrounding soil;

L ground electrode length, m;

d diameter of ground electrode, m;

p soil resistivity, Ohm*m;

Horizontal electrode resistance:

where p soil resistivity, Ohm*m;

b - width of the horizontal electrode tape, m;

h - laying depth of the horizontal mesh, m;

L - horizontal electrode length, m

Impedance of the grounding device:

where n - number of kits;

k - Utilization ratio;

The design resistance of the grounding device is 0.98 ohms, which is less than the required value of 1 ohms.

Accessories for functional grounding

№	Fig.	Product item	Product	Quantity
1.		ZZ-100-102-6МВ	ZANDZ Electrolytic grounding kit (vertical; 9 meters)	5
2.		GL-11075-10	GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 10 meters)	3
3.		ZZ-005-064	ZANDZ Clamp for connecting conductors (up to 40 mm)	7
4.		ZZ-007-030	ZANDZ Waterproof tape	3

 

Do you need to organize functional (working) or protective grounding in a confined space? Please contact our ZANDZ Technical center!

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