# Lightning Protection of a Natural Gas Fuelling Complex in the Territory of the Administration for Underground Gas Storage

The ZANDZ Technical Centre has received a request to calculate the lightning protection and grounding system for a natural gas fuelling complex located in the territory of the administration for underground gas storage (AUGS). Let's consider the solution proposed by our engineers.

Calculation data:

1. Facility: a natural gas fuelling complex.

2. Facility layout.

3. Heights of the protected zone: 7.5 m and 10 m.

4. Soil resistivity: 100 Ohm*m.

1. Calculate the external lightning protection system.

2. Calculate the grounding device.

Solution:

The activities have been performed according to:

A set of arrangements to ensure compliance with the requirements of the lightning protection system for the natural gas fuelling complex is based on the following solutions:

1. The facilities are classified as Category II of the lightning protection. The system reliability shall be at least 0.95

2. The facility lightning protection is made using 25 m lightning arresters (ZZ-201-025).

3. 3 m steel copper-plated rods are used as a vertical grounding arrangement.

4. The copper-plated steel strip with a cross-section of 30 x 4 mm, combining all vertical electrodes, is used as a horizontal ground electrode. Strip deepening is 0.5 to 0.7 m.

5. All reservoirs are connected to the grounding arrangement in 2 points.

6. Connection to the grounding device is carried out using ZZ-005-064 clamps.

7. The design resistance of the grounding arrangement is 3.31 Ohm.

8. According to EIC-7 issue, par.1.7.55, Grounding devices for protective grounding of electrical installations for buildings and structures and the 2nd and 3rd categories lightning protection of these buildings and structures, as a rule, shall be common.

Ground terminal resistance calculation:

Vertical electrode resistance:

Верт - Vert
Экв - Eq
Ом - Ohm

where    ρ ρeq – is equivalent soil resistivity, 100 Ohm·m;

L – is vertical electrode length, 3 m;

d – is vertical electrode diameter, 0.014 m;

T – is depth, i.e. the distance from the ground surface to the ground electrode, 2 m;

where     t  – is electrode top depth, 0.5 m.

Horizontal electrode resistance:

Гор - Hor
Ом - Ohm

where    ρ – is soil resistivity, 100 Ohm·m;

b - is horizontal electrode width, 0.03 m;

h - is horizontal electrode depth, 0.5 m;

Lhor – is horizontal electrode length, 74 m.

Electrical impedance of the grounding arrangement:

ЗУ - GA
Ом - Ohm

where n is a number of sets, vertical grounding arrangements - 7 pcs, horizontal grounding arrangement - 1 pc;

Kutil – is utilization rate, 0.55.

The calculated resistance of the grounding arrangement is 2,29 Ohm.

Calculation of the protection zone:

Lightning arrester No. 1 - 2 (ZZ-201-025):

h = 25 m;

Cone height according to SO, Table 3.4:

h0 = 0,8h = 20 m;

Cone radius according to SO, Table 3.4:

r0 = 0,8h = 20 m;

Distance between the lightning arresters (maximum):

L = 59 m;

Limit distance between lightning arresters according to SO, Table 3.6:

Lmax = 4,75h = 118,75 m;

L0 = 2,25h = 56,25 m;

Sagging height:

To provide protection with the required reliability, radius rcx at the height h0 = 7.5 m is determined as follows:

To provide protection with the required reliability, radius rcx at the height h0 =10 m is determined as follows:

Для зоны защиты требуемой надежности радиус r0 на высоте h0 = 7.5 m is determined as follows:

To provide protection with the required reliability, radius rcx at the height h0 =10 m is determined as follows:

The layout of the equipment is shown in Figure 1.

>Выезд на трассу - Road to motorway
Ж.б. плиты - Reinforced concrete slabs
Котельная УПХГ - AUGS boiler
Пожарный резервуар - Fire tank
Условные обозначения: - Legend:
- молниеприемник-мачта высотой 25 м - 25 m lightning rod
- полоса стальная оцинкованная сечением 30х4 мм - Steel zinc-plated bar 30 x 4 mm
- зажим для подключения проводника - Clamp for connecting conductors
- вертикальный заземлитель длиной 3 м - 3 m vertical grounding arrangement
- зона защиты на H=10 м - Protection zone at H = 10 m
- зона защиты на H = 7,5 м - Protection zone at H = 7.5 m

Figure 1. Equipment layout.

The list of necessary materials is provided in Table 1.

Table 1. List of needed materials.

 № Part number Name Quantity, pcs. Unit weight, kg Note 1. ZZ-201-025 ZANDZ 25 m vertical lightning arrester (zinc-plated steel; with parts embedded under the foundation) 2 2. GL-11075-50 GALMAR Copper-plated strip (30 x 4 mm / S 120 mm²; 50-meter strip bundle) 3 0,98 В метрах 3. ZZ-001-065 ZANDZ Copper-plated threaded grounding rod (D14; 1.5 m) 24 2,00 4. ZZ-002-061 ZANDZ Threaded coupling 13 0,08 5. ZZ-003-061 ZANDZ Termination 12 0,07 6. ZZ-004-060 ZANDZ Guide head for jackhammer attachment 5 0,09 7. ZZ-005-064 ZANDZ Conductor connection terminal (up to 40 mm) 20 0,16 8. ZZ-006-000 ZANDZ Conductive grease 2 0,10 9. ZZ-007-030 ZANDZ Waterproofing tape 7 0,40 10. ZZ-008-000 ZANDZ Attachment to the hammer (SDS max) 1 0,50

Do you have any questions regarding lightning protection for the natural gas fuelling complex? Please contact the ZANDZ Technical Center!

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