The ZANDZ Technical Center has received a request to calculate the functional grounding arrangement for the stadium in Sochi. The calculation was made in two ways: conventional calculation and calculation using a software developed by OAO "Energy Institute named after G.M. Krzhizhanovsky" (OAO "ENIN").

Initial data:

- soil resistivity:

top layer - 150 Ohm*m;

lower layer - 70 Ohm*m;

- available area: triangle 15 x 7 m.

to calculate functional grounding arrangement with the resistance not exceeding 2 Ohm.

Solution:

A set of measures to ensure the requirements for the grounding arrangement of a football stadium is based on the following solutions:

1. Installation of 6 vertical electrodes. Electrodes are combined using a horizontal grounding arrangement.

2. Steel copper-plated rods D = 17 mm, L = 30 m are used as a vertical grounding arrangement. The thickness of the copper coating is at least 250 mcm.

3. A steel copper-plated bar 30 x 4 mm is used as a horizontal grounding arrangement. The thickness of the copper coating is at least 70 mcm. Depth is 0.5 to 0.7 m.

4. Connection to the grounding device is carried out using a GL-10333N clamp.

Ground terminal resistance calculation:

Equivalent resistivity of a double-layer soil:

ρ_экв=(ρ_1∙ρ_2∙L)/(ρ_1∙(t+L-h)+ρ_2∙(h-t)) = 77,6 Ohm;

where ρ_1 is top soil layer resistivity, 150 Ohm·m;

ρ_2 is lower soil layer resistivity, 70 Ohm·m;

h - is top soil layer depth, 6 m;

L is electrode length, 30 m;

t is horizontal electrode depth, 0.5 m;

seasonal ratio is not used.

Vertical electrode resistance::

Верт - Vert
Экв - Eq
Ом - Ohm

where    ρρeq is equivalent soil resistivity, 77.6 Ohm·m;

L is vertical electrode length, 30 m;

d is vertical electrode diameter, 0.017 m;

T is depth, i.e. the distance from the ground surface to the ground electrode, 15.5 m;

where     is electrode top depth, 0.5 m.

Horizontal electrode resistance:

Гор - Hor
Ом - Ohm

where    ρ is soil resistivity, 150 Ohm·m;

b is horizontal electrode width, 0.03 m;

h is horizontal electrode depth, 0.5 m;

Lгор is horizontal electrode length, 38 m;

Electrical impedance of the grounding arrangement:

ЗУ - GA
Ом - Ohm

where n is a number of sets, vertical grounding arrangements - 6 pcs, horizontal grounding arrangement - 1 pc;

Kutil is utilization rate, 0.45.

Results of the calculations performed by using the software developed by OAO G.M. Krzhizhanovskiy Energy Institute (OAO ENIN):

Панель результатов 1 - Result panel 1
ПАНЕЛЬ РЕЗУЛЬТАТОВ РАСЧЕТА - CALCULATION RESULT PANEL
Контур образован набором горизонтальных и вертикальных электродов с координатами, задаваемыми Пользователем - The circuit is formed by a set of horizontal and vertical electrodes with the coordinates set by the User
РЕЗУЛЬТАТЫ РАСЧЕТА - CALCULATION RESULTS
Сопротивление контура заземления – 1,245 Ом - Grounding circuit resistance – 1.245 Ohm
Напряжение на контуре заземления – 1,25 В - Grounding circuit voltage – 1.25 V
Коэффициент использования контура Ks = 0,4135 - Circuit utilization ratio Ks = 0.4135
Суммарная длина электродов контура – 218,6 м - Total circuit electrode length – 218.6 m
ОКНА ПРОСМОТРА ПАРАМЕТРОВ ОБЪЕКТОВ - FACILITY PARAMETERS VIEW
Для отображения информации в окнах просмотра – нажмите клавишу «Просмотр» в интересующем Вас «БЛОКЕ ПРОСМОТРА» - To show information in the views, press “View” button in the “VIEW UNIT” of interest
Повторить расчет - Repeat calculation
БЛОКИ ПРОСМОТРА - VIEW UNITS
Сохранить результаты расчета в текстовом файле - Save calculation results in a txt file
Для выхода из программы – нажмите клавишу «Закончить работу» - Press “Finish work” to exit the application
Закончить работу - Finish work
Горизонтальные электроды - Horizontal electrodes
Просмотр - View
Вертикальные электроды - Vertical electrodes
Просмотр - View
Потенциальные точки - Potential points
Просмотр - View
Расчет проведен при следующих параметрах: - Calculation is performed using the following parameters:
Тестовый ток – 1,0 А - Test current – 1.0 A
Глубина заложения контура – 0,50 м - Circuit depth – 0.50 m
Удельное сопротивление грунта – 77,60 Ом.м - Soil resistivity – 77.60 Ohm.m

Estimated resistance of a grounding arrangement is 1,23 Ohm and 1.,45 Ohm, which is less than the required resistance of 2 Ohm.

The location of the equipment is shown in Figure 1.

The list of the required materials based on the calculation results is shown in Table 1.

7 м - 7 m
Условные обозначения: - Legend:
- полоса стальная оцинкованная сечением 30х4 мм - Steel zinc-plated bar with cross-section 30 x 4 mm
- зажим для соединения проводников - Clamp for connecting conductors
- Вертикальный заземлитель длиной 30 м - 30 m vertical grounding electrode

Figure 1. Equipment layout.

Table 1. List of needed materials.

 Item # Part number Name Quantity, pcs. 1. GL-10021 GALMAR Copper-plated threaded grounding rod (D17; 1.2 m) 150 2. GL-10403 GALMAR Threaded coupling (D17) 145 3. GL-10603 GALMAR Termination (D17) 6 4. GL-10803 GALMAR Guide head for jackhammer attachment (D17) 30 5. GL-10333N GALMAR Clamp for connecting conductor (D17; p. <40 mm; stainless steel) 7 6. ZZ-006-000 ZANDZ Conductive grease 15 7. ZZ-007-030 ZANDZ Waterproofing tape 2 8. ZZ-008-000 ZANDZ Attachment to the hammer (SDS max) 2 9. GL-11075-50 GALMAR Copper-plated strip (30 * 4 mm / S 120 mm²; 50-meter strip bundle) 1