The ZANDZ Technical Center has received a request to develop lightning protection for an elevator plant. Further, we will consider what solution we have offered.
Initial data:
- facility: an elevator plant;
- architectural drawings;
- soil resistivity: 100 Ohm*m.
Task:
To calculate the lightning protection and grounding system.
Solution:
The activities have been performed according to:
- EIC Rev. 7. (hereinafter referred to as the EIC);
- SO 153-34.21.122-2003 Instructions for Mounting Lightning Protection for Buildings, Structures, and Industrial Utilities (hereinafter referred to as SO);
- RD 34.21.122-87 Instructions for Mounting Lightning Protection for Buildings and Structures (hereinafter referred to as RD).
According to the EIC Rev. 7, item 1.7.101. the resistance of the grounding arrangement should not be more than 4 Ohm in any season of the year.
A set of arrangements to ensure compliance with the requirements of the lightning protection system for the elevator plant is based on the following solutions:
- 16 x 10 m lightning rods are installed by their attachment to the wall. It is taken into account that 2 m of the height of lightning arrester are necessary for mounting.
- installation of 8 x 8 m lightning rods is carried out by attachment to the wall. It is taken into account that 1,5 m of the height of lightning arrester are necessary for mounting.
- installation of 2 x 7 m lightning rods is carried out by attachment to the wall. It is taken into account that 1,5 m of the height of lightning arrester are necessary for mounting.
- lightning arresters are interconnected to arrange two current collectors using zinc-plated steel wire D = 8 mm from each lightning arrester. Current collectors are connected to an artificial grounding arrangement in 14 points. Current collectors are attached (installation spacing 0.6-1 m) to the roof using clamps GL-11747A, and on the wall - using clamps GL-11703A;
- connection and branching of current collectors are made using clamps GL-11551A.
- installation of a grounding arrangement consisting of a horizontal electrode (steel zinc-plated strip having a cross-section 4 x 30 mm), depth 0.5 m, and 14 x 3 m vertical electrodes 3(rods made of zinc-plated steel having diameter 14 mm);
- interconnection of vertical and horizontal electrodes is carried out using clamp ZZ-005-064;
- current collector is connected with the output of the zinc-plated ground strip using control clamp GL-11562A;
- according to item 1.7.55 of the EIC, "Grounding arrangements for protective grounding and grounding for lightning discharges are common."
Ground terminal resistance calculation:
Vertical grounding arrangement resistance:
Верт - Vert
Экв - Eq
Ом - Ohm
where ρ – is equivalent soil resistivity, 100 Ohm·m
L – is vertical electrode length, 3 m;
d – is vertical electrode diameter, 0,014 m;
T – is deepening;
t - is the distance from the ground surface to the grounding arrangement, 0.5 m;
м - 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 grounding depth, 0,5 m;
Lhor is horizontal electrode length, 516 m.
Electrical impedance of the grounding arrangement:
ЗУ - GA
where n is number of vertical grounding arrangements - 14 pcs; horizontal grounding arrangements - 1 pc;
kutil is utilization rate, 0.5;
estimated resistance of the grounding arrangement is 0,89 Ohm, which is less than the required value of 4 Ohm.
The location of the equipment is shown in Figure 1.
План кровли - Roof plan
Условные обозначения: Legend:
- стержневой молниеприемник; - lightning rod;
- горизонтальный заземлитель; - horizontal grounding electrode;
- вертикальный заземлитель длиной 3 м; - 3 m vertical grounding electrode;
- токоотвод; - current collector;
- зажим для подключения проводника - clamp for connecting wire
- зажим для соединения токоотводов - clamp for connecting current collectors
- зажим контрольный (проволока+полоса) - control clamp (wire + bar)
Figure 1. Equipment layout.
The list of necessary equipment and materials is provided in Table 1.
Table 1. List of needed materials.
Contact us to get free calculations for lightning protection and grounding for any facility We are happy to help you!
Related Articles:
