GROUNDING OF OVERHEAD POWER LINES IN PERMAFROST GROUND

When designing overhead power lines in the Chukotka Autonomous Region, one of our customers faced difficulties in organizing grounding. Geological data indicated too high electrical resistivity of the soil - from 30,000 to 80,000 Ohm * m. This problem is not uncommon in permafrost soils, and the ZANDZ Technical Center specialists have a reliable and proven solution for it: installation of electrolytic grounding kits.

Let us consider in more detail how our engineers solved the problem of designing the grounding device for the overhead line support in permafrost soil.

 

Task: It is necessary to calculate the grounding device for the support of the overhead power line 110 kV.

Initial data:

• object: single-circuit 110 kV overhead line on metal supports of type 1Y110-3 +5 according to the series 3.407.2-170, Chukotka Autonomous Region;

• electrical resistivity of soils from 30,000 to 80,000 Ohm * m.

In accordance with EIC, p. 2.5.129 chart2.5.19, the resistance of the grounding device of the 110 kV overhead line should be no more than 480 Ohms.

 

The set of measures on the provision of the necessary requirements to the grounding device (electrolytic grounding) is presented by the following solutions:

- installation of 7 sets of electrolytic grounding ZZ-100-102 and the implementation of the grounding contour along the perimeter of the overhead line support. The distance from the electrodes to communications and foundations should be at least 3. Depth 0.6 m;

- the grounding device must be connected to the reinforced concrete foundation of the support.

Grounding device resistance calculation:

The design resistance of the grounding device is 463,03 Ohm, which is less than the required value of 480 ohms.

 

Location of equipment is shown in figure 1.

The list of required material is given in Table 1.

Условные обозначения- Type Codes
Полоса стальная оцинкованная сечением – Galvanized steel tape with the cross section of 30*4 mm
Зажим для соединения проводников – Clamp for connecting conductors
Комплект электролитического заземления – Electrolytic grounding kit

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