Tecnical calculation of module-rod grounding device made of copper-bonded steel for a UTS 10/0,4 kW

Appendix № 3 to "Economic justification of using ZANDZ modular grounding".

The activities were carried out in accordance with the EIC 7 th ed. Chapter 1.7

The object of the protective grounding installation a unit transformer substation (UTS) with the voltage of 10/0,4 kW. According to the customer's data, the ground in the intended place of grounding devices installation is clay loam. Specific soil resistance is taken equal to 100 Ohm ∙ m.

In accordance with the EIC p.1.7.96, 1.7.97 and 1.7.104 for electric installation with the voltage above 1 kW in networks with the isolated neutral (35-10 kW), the grounding device resistance should not exceed 4 Ohms.

In accordance with EIC 1.7.101 the resistance of the grounding device, to which the neutrals of the generator or transformer or single-phase current supply terminals are connected, should not exceed 4 ohms at any time of the year at the line voltage of 380 W of a three-phase power source.

The set of measures to ensure the necessary requirements to the grounding device is represented by the following solutions:

  • installation of two vertical electrodes 10.5 m long and one vertical electrode 9 m long of steel copper-bonded rods with the diameter of 14 mm, united by a horizontal ground electrode of stainless steel copper-plated corrosion-resistant tape with the cross-section of 4x30 mm, laid around the UTS. Depth of the tape burial 0.5 m;
  • a horizontal ground electrode 1 meter long is laid to the wall of the UTS (copper-bonded tape with cross-section of 4x30 mm).

Arrangement of elements of the grounding device is shown on Figure 1.

Figure 1 - grounding device elements layout

Figure 1 - grounding device elements layout

Условные обозначения – code designations

Вертикальный электрод длиной – vertical electrode 10,5 m long

Горизонтальный электрод – horizontal electrode

Зажим для подключения проводника – clamp for connecting conductor

Calculation of a grounding device resistance:

Horizontal electrode resistance:

Horizontal electrode resistance

  • p — soil resistivity, Ohm*m;
  • b — width of the horizontal electrode tape, m;
  • h — laying depth of the horizontal mesh, m;
  • Lгор — horizontal electrode length, m.

Vertical electrode resistance:

Vertical electrode resistance

Where p - soil resistivity, ohm-m; 
L - vertical electrode length, m; 
 - vertical electrode diameter, m; 

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

T - burial

t – deepening of the electrode top, m

Impedance of the grounding device:

Impedance of the grounding device

Where n - number of kits;
kисп - coefficient of use;

The design resistance of the grounding device is 3.94 ohms

The design resistance of the grounding device is 3.94 ohms.

The list of required materials:

№ п/п Fig. Product item Product Quantity
1.   ZZ-000-030 ZANDZ Universal grounding kit (30 meters) 1
2.   GL-11075-20 GALMAR copper-bonded tape (30 * 4 mm / S 120 mm², coil of 20 meters) 1
3.   GL-11075-10 GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm², coil of 10 meters) 1


See further - Appendix № 4. Local costing № 031 (application of ZANDZ modular grounding of vertical steel rods with the diameter of 14 mm and 1,5 long, covered by electrolytic deposition of copper with the purity of 99.9%, with the coating thickness 250 micron).

Do you need to make the project on grounding and lightning protection? Order it by contacting the ZANDZ.ru Technical Center!


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