First Year Operation Events for EgyptSat-1: Ground Control Station Lightening strike and Protection Measures"

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1 First Year Operation Events for EgyptSat-1: Ground Control Station Lightening strike and Protection Measures" By Prof.Fatma Elhefnawi, Eng. Ahmed Yousef, Prof.Amal Zaki Prof.Dr.Fatma Elhefnawi 1

2 Outline 1. Introduction 2. Protection measures. 2.1 Strike termination devices,air terminal &zone of protection 2.2 Cable conductors 2.3 Grounding electrode station system 2.4 Bonding 2.5 Surge protection devices 2.6 lightning protection components 3. Conclusions Prof.Dr.Fatma Elhefnawi 2

3 1.Introduction Lightning and over-voltage voltage transients are major problems for telecommunications carriers throughout Eastern part of Egypt. Lightning may cause damage to cellular radio, and satellite telecommunications installations. High energy over-voltage voltage transients may be derived from direct lightning strikes to antenna towers or they may be conducted on power and telephone cables entering buildings and facilities. Prof.Dr.Fatma Elhefnawi 3

4 1.Introduction(cont) Two major consecutive strikes hit Egypt Sat I ground control station on the 17 Oct 2008 after one year of operation. The system has good protection against lightening strikes but unfortunately this was not enough for this part of Eastern part of Egypt where a lightening strike of more than 100KVA hit the station. Prof.Dr.Fatma Elhefnawi 4

5 2.Protection measures that need to be in place to provide an effective lightning protection system : 1. Strike termination devices, air terminal &zone of protection. 2. Cable conductors. 3. Grounding electrodes station system. 4. Bonding. 5. Surge protection devices. 6. lightning protection components. Prof.Dr.Fatma Elhefnawi 5

6 2.1 Strike termination devices Strike termination devices covering various areas of a structure and buildings were interconnected to form a single system either by roof conductors, and or down conductors, and by interconnection of the grounding belt at the ground belt or roof belt,then to the ground stations spots at Egypt Sat -I ground control station. Prof.Dr.Fatma Elhefnawi 6

7 Grounding Mesh on Roof top of Ground Control Station Of Egypt This figure shows Sat I the roof mesh Prof.Dr.Fatma Elhefnawi 7

8 2.2 Air Terminals and Zone of Protection Zone of protection described by using a rolling sphere model to identify items under the protection Prof.Dr.Fatma Elhefnawi 8

9 2.3 Cable Conductors &materials Rooftop loop, Rooftop mesh, Down conductor & Earthing belts on each building should made of materials that can carry such high current safely to its final destination without destruction or failure of any adjacent component. Copper, copper alloys (including brass and bronze), and aluminium are the basic system component materials. They serve the best combination of function for safe current carrying and bad weathering conditions. Aluminium materials have slightly lower current carrying capability and mechanical strength than similar sized copper products but less expensive. Prof.Dr.Fatma Elhefnawi 9

10 2.3 Cable Conductors &materials(cont) Down Cupper Conductors Prof.Dr.Fatma Elhefnawi 10

11 2.4 Grounding Electrode Station System 1. Properly made ground connections are essential to the effective functioning of a lightning protection system, as they serve to distribute lightning into earth ground. 2. Grounding electrodes must provide the proper earth contact to disperse the charge and satisfy requirements for life cycle suitability in various soil compositions. 3. Low resistance is desirable but not essential. 4. The grounding arrangement depends on the character 4. The grounding arrangement depends on the character of the soil, ranging from single ground rods where soil is deep, to the use of multiple electrodes, ground plates, radials, or buried wire networks where soil is shallow, dry, or of poor conductivity. Prof.Dr.Fatma Elhefnawi 11

12 2.4Grounding Electrode Station System (Cont) A grounding electrode network is determined at Egypt Sat-I I ground control station where a ground loop encircling a structure and interconnecting all down lead cables at their base /or at its floor loop. An in-ground loop solves this potential problem and provides an extensive wire network to enhance the grounding system. Prof.Dr.Fatma Elhefnawi 12

13 2.4 Grounding Electrode Station System(Cont) A ground loop is required for every structure exceeding 20 m in height. If an interconnecting loop cannot be installed in the earth, then it may be placed within the construction to fulfill this requirement. This ground level loop also accommodates connection with other building grounded systems. All grounding media in or on a structure shall be interconnected to provide a common ground potential using main sized lightning conductor. This includes the lightning protection grounding electrode system, electric, communication, antenna tower,and antenna system grounds along with metallic piping systems entering the structure like water. Prof.Dr.Fatma Elhefnawi 13

14 2.4 Grounding Electrode Station System(cont) Three nodes were implemented for a grounding station Prof.Dr.Fatma Elhefnawi 14

15 This Figure shows Tower Grounds on All four corners where they were connected to the tower legs. Prof.Dr.Fatma Elhefnawi 15

16 2.5 Potential Equalization (cont) The philosophy behind strike termination, conduction, and grounding is to accept the lightning and send it to ground. Bonding devices are sized to provide adequate interconnection of systems to create potential equalization throughout the structure. Prof.Dr.Fatma Elhefnawi 16

17 2.5 Potential Equalization (cont) Adequate interconnection. Prof.Dr.Fatma Elhefnawi 17

2.5 Potential Equalization (cont) Because this is the point where most lightning current passes, the grounds are wide flashing high temperature silver soldered to the ground rods,

18 2.5 Potential Equalization (cont) Because this is the point where most lightning current passes, the grounds are wide flashing high temperature silver soldered to the ground rods, this ground reduces current on wires leaving the tower for the house in the event the tower gets a direct hit, or has substantial charge from a nearby strike. Prof.Dr.Fatma Elhefnawi 18

19 2.5 Potential Equalization (cont) Because this is the point where most lightning current passes, the grounds are wide flashing high temperature silver soldered to the ground rods. This ground does not reduce the chances of a hit. It prevents the cable shields and control wires leaving the tower from being the sole path for lightning currents. in other words, this ground reduces current on wires leaving the tower for the house in the event the tower gets a direct hit, or has substantial charge from a nearby strike. Prof.Dr.Fatma Elhefnawi 19

20 2.6 Surge Protection Lightning protection systems are designed first and foremost as fire protection systems to stop the building from burning down and losing the people and equipment inside. Bringing metallic services into a structure provides paths for lightning to follow from the outside environment to create hazards within. Prof.Dr.Fatma Elhefnawi 20

21 2.6 Surge Protection (cont) We bond or interconnect grounds and pipes to the lightning protection system to avoid a portion of this problem. The next step is to provide protection on circuits associated with electrical, communication, and/or data lines that can transmit lightning into a structure. The severest problems are associated with utility service lines that are extensive systems, either pole mounted or buried, that can transmit additional strikes to the building. A complete lightning protection system according to the Standards includes surge protection devices at every entrance of building service conductors, whether they are utility or possibly structure-mounted like an antenna system. Prof.Dr.Fatma Elhefnawi 21

22 2.6 Surge Protection(cont) Surge protection devices (SPD)for( building entrances are designed to ride the line, sense over voltage problems, and send excessive energy directly to ground. Most devices have two or more internal elements to accomplish the task, and react at something around 150% of the standard operating voltage of the system. SPD elements can be thought of as self-sacrificial sacrificial and may burn out over time protecting against a multitude of small surges (like standard switching surges from power transmission) or a few massive surges like direct lightning attachments. Prof.Dr.Fatma Elhefnawi 22

23 2.6 Surge Protection(cont) Most devices have two or more internal elements to accomplish the task, and react at something around 150% of the standard operating voltage of the system. SPD elements can be thought of as self- sacrificial and may burn out over time protecting against a multitude of small surges (like standard switching surges from power transmission) or a few massive surges like direct lightning attachments. Prof.Dr.Fatma Elhefnawi 23

24 Roof Grounding Mesh Roof top of one of the building at Egypt Sat I Ground Control station Prof.Dr.Fatma Elhefnawi 24

25 3.Conclusions 1. The application of surge protection devices (SPD ) along with the current carrying components and interconnection of grounded building systems prove complete package for a full lightning protection system to protect structure, people, and equipment within. 2. The grounding electrode system may be protected from atmospheric conditions of weathering, but is subject to potential degradation from soil compositions and moisture. 3. A proper initial installation might be expected to provide protection forever or at least for the reasonable useful life particular building. Prof.Dr.Fatma Elhefnawi 25

26 3.Conclusion (cont) 4. There are additional conditions that require consideration. It is the maintenance for the lightning protection system. Maintenance is necessary. 5. Re-roofing the building, are obvious areas needing review and treatment. 6. Periodic inspection and maintenance to assure the system is functional when placed under lightning strike conditions is necessary and is expected to be repeated at specified interval of time at Egypt Sat-I I ground control station. Prof.Dr.Fatma Elhefnawi 26

27 3.Conclusions(cont) 7. The implementation of a lightning protection system includes training, and certification of individuals involvedin inspection of the complete lightning protection system. 8. Our aim should be focusing our efforts to educate professionals on safe and effective lightning protection schemes in future satellite ground stations in Egypt.This is the aim of NARSS at present time. 9. Implementation of early streamer and early protection lightening strikes by measuring the electromagnetic field from the charged clouds is expected. Prof.Dr.Fatma Elhefnawi 27

28 Thank You And Appreciate Your Attention Prof.Dr.Fatma Elhefnawi 28

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