Tecnical calculation of module-rod grounding device made of copper-bonded steel for a UTS

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 is 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-bonded 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

where t - deepening of the electrode top, m

Grounding device impedance:

Grounding device impedance

Where n - number of kits; kисп - utilization ratio;

The design resistance of the grounding device is 3.9 ohms

The design resistance of the grounding device is 3.9 ohms.

The list of required materials:

Fig. Product item Product Quantity
1. ZZ-000-130 ZZ-000-130 ZANDZ Universal grounding kit of stainless steel (30 meters) 1
2. GL-11075-20 GL-11075-20 GALMAR copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 20 meters) 1
3. GL-11075-10 GL-11075-10 GALMAR Copper-bonded tape (30 * 4 mm / S 120 mm²; coil of 10 meters) 1


See further - Appendix № 6. Local costing № 032 (application of ZANDZ modular grounding of vertical stainless steel rods with the diameter of 16 mm and 1,5 long).
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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