Usually, a hopper is a facilities complex consisting of a working building, grain-storage sections, grain loading and unloading devices, grain dryers, etc. To provide the lightning protection of the hopper, we need to protect its highest part wherein a vertical lift, i.e. the chain bucket, is located. Due to the chain bucket's height being about 70 meters, we have to install 10 m lightning arresters; lower arresters are simply useless.
Due to high lightning arresters, larger area is protected; therefore, in order to provide a good lightning protection for the hopper, you only need to install several more shorter lightning arresters. At least it seems like this in the calculation we have performed recently.
We will consider this example lightning protection for the hopper.
Task
To calculate the lightning protection and grounding for the hopper.
Solution
Calculations of the hopper lightning protection are made in conformity with the following regulatory documents:
- "Electrical Installations Code" (hereinafter referred to as the EIC), 7th edition.
- "Instructions for the installation of lightning protection of buildings, structures, and industrial communications" SO 153-34.21.122-2003 (hereinafter referred to as SO).
- "Instructions for mounting the lightning protection of buildings and structures" Working Documentation 34.21.122-87 (hereinafter referred to as the RD).
The lightning arresters are used to protect the buildings against lightning strokes. The lightning arrester consists of an interception rod, intercepting a lightning discharge, the main conductor cable, and the ground electrode. All these elements let us divert lightning current into the ground safely, without any damage to the protected facility.
The hopper is classified as Category 3 according to RD and as a special facility with the limited hazard in terms of lightning protection according to SO.
Description of the lightning protection and grounding system for the hopper
A set of arrangements ensuring compliance with the lightning protection requirements is based on the following solutions:
- Installation of 4 lightning rods 8 m high is carried out by attachment to the wall. It is taken into account that 1.5 m of the height of lightning rods are necessary for mounting.
- Installation of 4 lightning rods 7 m high is carried out by attachment to the wall. It is taken into account that 1.5 m of the height of lightning rods are necessary for mounting.
- Lightning arresters are interconnected to arrange two current collectors using galvanized steel wire D = 8 mm from each lightning arrester. The main conductor cables are mounted (with mounting step 0.6-1 m):
- to the walls using clamps GL-11703A.
- Connection and branching of current collectors are made using clamps GL-11551A.зажимов GL-11551А.
A set of measures to ensure the requirements for the grounding arrangement is based on the following solutions:
- Installation of 4 grounding arrangements consisting of a horizontal electrode (galvanized steel strip with a cross-section 4 x 30 mm), depth 0.5 meter, and 3 vertical electrodes (steel copper-plated pins with a diameter 14 mm) 3 m long.
- The connection of vertical and horizontal electrodes between each other is carried out with the use of clamp ZZ-005-064
- The connection of the current collector with the output of the galvanized ground strip is performed using the control clamp GL-11562A
- The design of the grounding arrangement corresponds to clause 1.7.55 of EIC Grounding arrangements of the protective
The location of the elements of the lightning protection system and the grounding arrangement is shown in Figure 1. The depicted protection area corresponds to area B, constructed as per Appendix 3 of WD.
Picture 1. Layout of lightning protection and grounding arrangement elements for the hopper (to request a full-size image, write to info@zandz.com)
План кровли - Roof plan Разрез А-А - Section A-A
Components for lightning protection and grounding of the hopper
Do you have any questions regarding the calculation of the lightning protection and grounding for a hopper? Please, contact the ZANDZ Technical Center!
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