ZANDZ Center has received this unusual request from Yakutsk. Not everyone know that Yakutsk has a status of the world's largest city in permafrost. There are fountains in Yakutsk as well as in any other city. The engineering system of one of the facilities under construction includes special pumps and control electronics. To provide reliable operation of the entire hydrotechnical system, the developer has used a grounding system with the resistance not more than 4 Ohm in a design.
In permafrost areas, even in summer, when the fountains are operated, we can achieve 4 Ohm only when using an electrolytic grounding system.
This particular solution was proposed by ZANDZ technical specialists for this facility in Yakutia. A hollow L-shaped electrode ZZ-100-102 filled with a dry electrolyte was chosen. Due to the controlled dissolution of the electrolyte in the soil surrounding the electrode, soil resistivity is reduced. As a result, the grounding resistance for each set is significantly lower than the resistance of a common grounding arrangement of the same size.
During the calculation, we will show how many electrolytic grounding electrodes were required to achieve the grounding resistance less than 4 Ohm. You can see the calculation below.
Task
To calculate the fountain grounding in Yakutsk.
Solution
Solutions for grounding a fountain were made in accordance with the 7th edition of the Electrical Installation Code.
Description of the fountain grounding system
- To provide the rated resistance of the grounding device, electrolytic grounding ZANDZ ZZ-100-102 is proposed.
- Installation of 5 sets of electrolytic grounding ZANDZ ZZ-100-102, which are combined with a horizontal grounding device made of a corrosion-resistant steel copper-plated strip 4 x 30 mm (GL-11075), is provided as a circuit around the entire building.
- All sets were placed at a distance of 6 meters with a parallel arrangement to achieve the acceptable utilization rate and an optimal volume of electrolyte distribution in the soil.
- The grounding devices are connected using clamps ZZ-005-064.
Figure 1. Fountain grounding layout
Calculation of the grounding arrangement for the fountain
Upon agreement with the customer, the calculated resistivity of a permafrost soil is taken as 1,000 Ohm∙m.
Warning! In case the Customer provided erroneous and limited soil data, the above calculation of a grounding arrangement is considered incorrect. If the soil resistivity differs from the calculated one, it is necessary to perform computations with a real value. If the normalized impedance of the grounding arrangement is exceeded, there must be introduced the design corrections.
The calculation is made using formulas provided in the Grounding Calculation page.
The calculation formulas with the completed data are shown below.
Ом - Ohm
Исп - util
Гор - hor
The calculated resistance of the grounding arrangement is 3.73 Ohm, which is less than the required value of 4 Ohm.
Components of the fountain grounding system
| № | Part number | Name | Quantity, pcs. |
| Grounding arrangement | |||
| 1. | ZZ-100-102 | ZANDZ Electrolytic grounding set (horizontal; 3 meters long) | 11 |
| 2. | GL-11075-50 | GALMAR Copper-plated strip (30 * 4 mm / S 120 mm²; 50-meter strip bundle) | 1 |
| 3. | GL-11075-20 | GALMAR Copper-plated strip (30 * 4 mm/ S 120 mm²; 20-meter strip bundle) | 1 |
| 4. | ZZ-005-064 | ZANDZ Conductor connection terminal (up to 40 mm) | 11 |
| 5. | ZZ-007-030 | ZANDZ Waterproofing tape | 4 |
Do you have any questions regarding fountain grounding in Yakutsk? Please contact the ZANDZ Technical Center!
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