indus grounding & lightning protection system

8/8/2019 Indus Grounding & Lightning Protection System

http://slidepdf.com/reader/full/indus-grounding-lightning-protection-system 1/16

- 1 -

♦ I n t r o d u c t i o n

♦ G r o u n d A u d i t

♦ D e s i g n♦ I n s t a l l a t i o n

♦ P r o d u c t D e t a i l s I E G S - G E

♦ L i g h t n i n g P r o t e c t i o n

♦ T e s t P r o c e d u r e s

♦ S e r v i c e s O f f e r e d

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -2 1 2 - B , S . M . C . H . S , K a r a c h i - 7 4 4 0 0 , P a k i s t a n

T e l : + 9 2 2 1 4 5 4 0 1 1 1 & C e l l : 0 3 2 1 - 2 4 3 7 1 9 1 & 2

i n f o @ i n d u s r e s o u r c e s . c o m

E l e c t r i c a l G r o u n d i n g &

L i g h t n i n g P r o t e c t i o n S y s t e m



- 2 -

ELECTRICAL GROUNDING

Few years ago it would have been rare for anyone to talk about the importance of low

resistance grounding and bonding except where mainframe computer systems,

telecommunications equipment or military installations were being discussed. Today,

we live in a world controlled by microprocessors so low resistance grounding is now

critical and is a popular topic of conversation

Low Impedance Electrical Grounding is essential for safety and protection of Sensitive

Electronic Equipment and also for the effective Lightning Protection System (LPS). It is

the basis for any facility's power quality assurance program.

According to the IEEE Green Book [3] (Recommended Practice for Grounding,

ANSI/IEEE Standard 142-1982), the grounding electrode resistance of large electrical

substations (utilities) should be 1 Ohm or less. For commercial and industrial

substations the recommended ground resistance is 5 Ohms or less. This low resistance

is required due to the high potential to earth of the electrical system. Many

equipment vendors and communication companies require ground systems of less

than 3 Ohms resistance. For Lightning Protection system, BS 6651 stipulates that the

resistance to earth of the LPS measured at any point should not exceed 10 ohms.

To prevent damage and insure proper operation of modern sensitive communications

and electrical equipment, dissipation of lightning energy and good return paths for

ground fault currents has become a necessity. These modern, sensitive equipments

include Computer Systems and other Electrical and Electronic equipments in Banks,

Offices Call Centers, Magnetic Imaging equipment, Telecom Installations & Microwave

Towers, CNC Machines and other Sophisticated Electronic equipment used in different

Industries Offices and Electric Power Substations.

Proper grounding has other benefits, such as Enhanced Personnel Safety, Reduction in

System Noise and Protection from Unwanted Voltages, Currents and Power Surges and

Protection from Lightning. Without a proper “Low-Impedance Ground”, standard

protection devices such as breakers - or transient voltage surge and lightning protectionsystems - are rendered ineffective. Several Electronic Equipment Manufacturers,

especially Communications Equipment Manufacturers such as Ericsson, Lucent, and

Motorola & Nortel may void their equipment warranties at sites where the ground

system performance does not meet their explicit earth grounding requirements,

typically 5 ohms or less.



- 3 -

GROUND AUDIT: TESTING OF EXISTING FACILITIES

When Grounding systems are installed they are required to meet certain resistance

criteria, such as 10, 5, 3 or 1 ohm. Unfortunately most grounding systems are not

properly maintained and tested after installation. Since they are buried they are also

difficult to inspect. The Grounding system in many of the Industrial & Commercial

facilities are decades old and most of them are corroded and have undetected electrical

discontinuities. These Problems often continue for many years, contributing to electrical

problems, equipment failures and decrease in personnel safety.

We do the Complete Audit / Evaluation of Grounding System & LPS by using Fall of

Potential Method Testing for the Resistance values of the Existing Grounding System

and suggesting the rectifications if necessary.

DESIGN, INSTALLTION & TEST-PROCEDURES

In order to understand Electrical Grounding Design, Installation and Test -Procedures, it

is necessary to review why grounding is important. The list below gives some of the

basic advantages of an effective ground system.

Limits voltage in an Electrical Distribution system to “Definite Fixed Values”

Limits Voltage to within “Insulation Ratings".

Provides a “More Stable System” with a minimum of “Electrical Noise” and

“Transient over Voltage”.

Provides a path to ground in fault conditions for quick isolation of equipment

with operation of “Ground Fault Protection”.

Provides grounding of all conductive enclosures that may be touched by

personnel, thereby “Eliminating Shock Hazards”.

Reduces “Static Electricity” that may be generated within facilities.

Provides “Protection from Large Electrical Disturbances” (Such as Lightning)

by creating a low resistive path to earth.



- 4 -

Computers are very sensitive electronic devices, and commonly experience data

corruption in non-grounded or poorly grounded environments, as well as outright

physical damage. This can easily happen at voltages less than can be felt by the human

hand. Computer chips operate at 5 volts and less. Computer chips can be damaged by

10 volts, and data corruption can happen in many other cases. More and More

machineries are coming with electronics and microprocessors.

The microprocessor chips themselves have become smaller and more densely packed.

This decreases heat dissipation, and makes them less robust. Operating voltages have

and continue to decrease to allow for this miniaturization. A digital "1" may be in the

vicinity of 3.5 - 5.0 volts or less, and a "0" in the range of 0 - 1.5 volts. So smaller over

voltages from transient conditions may result in operating errors and this can happen

with improper grounding.

Many people complain that the power from the power company is bad. Few of us must

have gotten a power surge from the power company because their computer quit

working. However, the real problem is usually not a surge from the Power Company, but

instead just a bad grounding. People spend money on surge protectors and line

conditioners but usually do not get any improvement. On the other hand, those who

simply ground their power outlets properly usually see their problems go away entirely,

without needing a surge protector or line conditioner. A surge protector and line

conditioner give additional protection, but we cannot get a "ground" by adding a line

conditioner, surge protector or other equipment. You get a ground only by grounding.

With computers, by far the most common devices to fail and need replacement are the

modem, printer and printer port, sound card, video card and LAN card (network not

grounded). Intermittent data corruptions are caused because the data travels at 4.7

volts or less inside the computer, yet the power outside is 220 volts. Without proper

grounding/earthing, the exposed metal on the back of the computer is typically 40-100

volts and fluctuating. Data corruption comes from leakage current.

If a telecom company's grounding systems falter, then equipment fails, calls drop and

people are inconvenienced. Companies will have a difficult time staying alive in an

increasingly competitive industry if their service levels decrease. With equipment

sensitivity also steadily increasing, installing a ground right the first time is even morecritical.

Only through proper electrical site protection can telecom companies ensure effective

grounding and the best protection for their cellular sites and switches. This may take

relearning the basics and grasping the engineering design and testing process, but

designing a proper ground will result in maintenance-free years of high-quality

performance and eliminate the need for rework or enhancement



- 5 -

SOIL RESISTIVITY TEST

The first step in designing a proper “Electrical Ground” starts with soil resistivitymeasurements. It is a crucial first step on which the remaining steps in the process are

based. Although not difficult, measuring soil resistivity can be time-consuming and

requires training, practice and the right equipment, including a four-pole ground

resistance test meter, reels of conductor and four probes. Soil resistivity measurements

must be taken in at least three different directions at four or five probe spacing, even on

the smallest land areas. This involves driving probes into the earth several times in each

direction. The more probes and data, the more accurately the designer can model the

site to provide the most effective design.

Variations of soil resistivity can range from 500 ohm-cm in clay to higher resistivity in

limestone - 5000 to 1,000,000 ohm-cm or more. Even in adjacent lots they dictate the

ground system performance within each site.

Electrical Grounding Design Process

Our extensive experience in the Designing of Electrical Grounding enables us to define

exactly what grounding installations will work best for your site. This eliminates “Trial &

Error”, and reduces the overall cost of the grounding system by designing only what is

needed to meet your specifications. Armed with reliable “Soil Resistivity” data and a site

map, our designer can complete the ground system design very accurately. A

sophisticated computer program uses this information to model the soil and grounding

system and recommend the quantity, type, length and shape of the ground rods,

including rod spacing and placement.

At this point, the drawings and other details are given to our installation department.

Installation of IEGS

The system we offer is called INDUS-Electrical Grounding System (IEGS).

The INDUS- Electrical Grounding System (IEGS) is backed by a team of Professional

Electrical Engineers who are experienced in the design, testing and application of all

types of grounding rods and systems.



- 6 -

ADVANTAGES OF INDUS-ELECTRICAL GROUNDING SYSTEM

Accurate Mapping of Soil Resistivity of Sites

Soil Resistivity Measurement is an essential part in designing the Low impedance

grounding and we do these measurements by using top of the line equipment and

through universally accepted Wenner method developed by Dr. Frank Wenner of the

US Bureau of Standards.

Designing through Software

“Proper Designing of Grounding System” is done, through the Internationally acceptable

grounding Software to get the accurate design for the required value of GroundResistance, prior to the installation of Grounding Pits / Rods , thus eliminating the “hit

and trial method” to achieve the required ground resistance values.

Permanent Soil Treatment Solution

IEGS Ground Rod comprises of a 1” to 2 “or larger hollow copper rod. These electrodes

are filled with an electrolytic salt mixture and derive moisture from the soil and

atmosphere and utilize the moisture to slowly dissolve the electrolytes in the rod

creating a conductive rooting effect, providing an ever increasing lower resistance

ground in any type of soil.

Ground Conductivity Enhancing Material

The High Resistivity Native Soil from the hole bored for the installation of IEGS ground

rods is replaced with the Low Resistivity Soil, called GCEM (Ground Conductivity

Enhancing Material) which provides a good Conducting path by creating a direct low

resistance electrical connection between the electrode and the earth.

Reducing the Risk of Equipment Damage

The high resistivity native soil around the grounding electrodes can cause a high

concentration in the electric field around an electrode, which in turn, may cause arcing

in the soil to occur and can lead to the Equipment Damage. The use of GCEM (Ground

Conductivity Enhancing Material) in our IEGS reduces impedance by increasing the

effective contact area of the electrode to the soil thus reducing the risk of Equipment

Damage.



- 7 -

Making Valid Measurements of Electrical Grounding

The neutral to ground voltage depends on wire size and length of the ground and

neutral, quality of connections, resistance of ground pits/rods etc. Excessive voltage

drop in the phases, high harmonics and poor Grounding shows high neutral to ground

voltages. The variability in the many factors which affect the neutral to ground voltage

partially explains that the neutral to ground voltage is not the VALID method of gauging

the quality of Electrical-Grounding. The most accurate method of measuring the

Electrical Grounding is the measurement of its “Resistance” through “Fall of Potential

Method”. We use top of the Line equipment DET 5/4 R for the measurement of Ground

Resistance which gives the most accurate results for the values of Ground Resistance.



- 8 -

IEGS-GE

IEGS Ground Electrodes provide a low-impedance ground in locations of high soil

resistivity. Together with GCEM as backfill, the system dissipates lightning energy and

other dangerous electrical fault currents, even in sandy or rocky soil conditions.

Features1 to 2 inch OD copper pipe contains natural electrolytic salts that permeate into the

surrounding soil, lowering resistivity. Available up to 20 feet in continuous length and

longer rods can be field assembled using 6.66 feet sections

Applications

The IEGS Ground Electrode system is ideal for locations of high soil resistivity as well as

the locations where Low Impedance Grounding is required

More Information

Ground Electrodes IEGS are self contained electrolytic grounding electrodes that extractmoisture out of the air and from the earth on a continuous basis. This moisture mixes

with and dissolves the metallic salts in the electrode that produces a continuous release

of electrolyte into the soil. This dramatically reduces the resistivity of the soil around the

electrode, thereby increasing the conductivity of the grounding system. The ground

resistance continues to diminish as the electrolyte spreads further into the soil and is

especially effective where the soil conditions are sandy, rocky, or have other undesirable

factors. In these cases, the lack of moisture or the lack of natural metallic salts fails to

produce a natural, conductive, electrolytic solution on a continuing basis. Our Grounding

system provides these missing low resistance ingredients. The IEGS incorporates several

features that overcome these adverse soil conditions. The IEGS's ability to extract

moisture from both the air and the soil simultaneously is one of these features. Whenthe topsoil is dry, the IEGS extract moisture from the air and from the earth at a depth

less susceptible to moisture variations. During a rainy season, the system extracts

moisture from both the air and topsoil. This ensures the maximum and continuous

development of the needed electrolyte. The INDUS- Electrical Grounding System (IEGS)

is backed by a team of Professional Electrical Engineers who are experienced in the

design, testing and application of all types of grounding rods and systems.



- 9 -

LIGHTNING PROTECTION

Cloud-to-Ground Lightning discharges can be hazardous to structures, people andinstallations or equipment in, on or connected to the structure. Lightning can cause

damage to all or part of a structure or to the contents of a structure, especially to

electrical and electronic system. Consequential effects of lightning damage may extend

to the surroundings of a structure.

To reduce lightning damage and its consequential effects, lightning protection measures

are required. The basic idea is to provide lightning current a separate preferential solid

path to ground.

Today, a lot of international and national rules exist to employ all well-tried measures to

protect life, structures and equipment. Account must be taken of the most important

international standards, such as IEC 61024-1 and 61312-1 (protection of building

structures against lightning and protection of information systems against LEMP –

including radio transmitters), BS 6651 and others. They all define the proper planning,

installation and inspection of effective lightning protection systems (LPS).

LIGHTNING PROTECTION DESIGN CONSIDERATIONS

All International standards stated above clearly advises strict adherence to the provision of a

conventional Lightning Protection System (LPS) - to the total exclusion of any other device or

system for which claims of enhanced protection are made.

The principle components of a conventional structural lightning protection system, inaccordance with these standards are:

Air Termination Network

Down Conductors

Earth Termination Network

Bonding (to prevent side flashing)

AIR TERMINATION NETWORK

On high risk structures such as explosive factories, no part of the roof should be more than

2.5m from an air termination conductor. This is generally achieved by applying a 5m x 10m

mesh to the roof.

However, for most structures, a mesh of 10m x 20m is considered sufficient, giving a

maximum distance from any part of the roof to the nearest conductor of 5m.



- 10 -

AIR TERMINATIONS FOR TALL CONDUCTING

STRUCTURES

The zone of protection does not seem to be

applied because of the need to interconnect the

down conductors of the tall block to the air

termination of the lower block.

In such cases it is necessary to connect the lower

air termination up to the lower down conductors

to facilitate this inter connection, even though

this extension is within the zone of protection of

the tower.

Zones of protection

The 'Zone of Protection' offered by an air termination network is considered to be 45º for

heights up to 20m. Above this height, the zone of protection is determined by the 'Rolling

Sphere Method'. This involves rolling an imaginary sphere of 60m radius over a structure. The

areas touched by the sphere are deemed to require protection. On tall structures, this can

obviously include the sides of the building.



- 11 -

EARLY STREAMER EMISSION TYPE AIR TERMINALS

The purpose of this type of air terminal is to emit a rising electrical discharge to inflect the

effect of the downward tracer. As it is transmitted towards the cloud, this rising discharge

creates a field which is sufficient to modify the path of the downward tracer: the lightning

current is thus dispersed into the earth. This process can occur naturally, but the action of

the IONIFLASH from FRANCE PARATONNERRES offered by IEGS triggers it more rapidly and

therefore ensures more effective protection.

DOWN CONDUCTORS: Down conductor siting and distancing is often dictated by

architectural circumstances. There should be one conventional down conductor for every

20m or part thereof of the building perimeter at roof or ground level (whichever is greater).

These should be evenly spaced and distances apart of more than 20m avoided if possible. If

the building is above 20m in height or of an abnormal risk this distance should be reduced to10m.

They should be routed as directly as possible from the air termination network to the earth

termination network to avoid risks of side flashing. Re-entrant loops are also to be avoided.

BS 6651 recommends that the length of conductor forming the loop should not exceed eight

times the width of its open side.

Conventional Down Conductors: Conventional down conductors are un-insulated

conductors, typically copper strip, or cable. To reduce the voltage rise, and the risk of side

flashing multiple down conductors are required. The use of multiple down conductors and

associated grounding systems, can add substantially to the cost. The ascetics of multipledown conductors have historically been an issue with architects and building contractors. The

conductor size shall be at least 28 strands of 14-gauge wire rope lay, with a net weight of

375 pounds per 1,000 feet (70mm2), minimum.

IEGS Down Conductors: INDUS has developed its dedicated insulated down conductor for

use with its IEGS Lightning Protection range. The cable is designed to provide a safe, insulated

path, to ground for the captured lightning discharge. Less numbers of down conductors are

required which allows for a simple high efficiency grounding network to be constructed. IEGS

Down Conductors can be routed away from sensitive electronic equipment & requires a

minimum of maintenance. The cable is capable of withstanding the full energy of the

lightning discharge and conveying this to the grounding system with minimal danger of sideflashing to adjacent earth points. The ability of this unique down conductor to screen

adjacent equipment from the large electro magnetic impulse associated with the discharge

current, is also a measure of it’s effectiveness in reducing damage by induction. This has

particular applicability to Telecommunications towers where the down conductor is by

necessity run parallel to the RF antenna cables down the length of the tower.

BS 6651 allows the use of 'natural conductors' such as rebars and structural steelwork,

provided that they are electrically continuous and adequately earthed. Otherwise use of

separate down conductors is a MUST



- 12 -

Inner area requires no conductors as it is within the zone of

protection determined by the rolling sphere

EARTH TERMINATION NETWORK

Each down conductor must have a separate earth termination. Moreover provision shouldbe made in each down conductor, for disconnection from the earth for testing purposes. This

is achieved with a test clamp of IEGS.

The peak current carried by the primary discharge during a lightning strike is almost 33 kA,

but can reach over 100 kA in some cases. Subsequent discharges (secondary strikes) typically

carry one third of that current. The rise time of the primary strike is about 4 micro seconds

while secondary discharges peak faster (less than 0.7 micro seconds) due to the fact that air

ionization keeps the conductive channel open. This is why it is important to keep the self-

resistance of the grounding system low; a high resistance system looks like an open circuit to

these impulsive currents and is thus ignored. To transfer a collected lightning strike safely

into the ground, an ultra-low impedance grounding system is necessary.

BS 6651 STIPULATES THAT THE RESISTANCE TO EARTH OF

THE LIGHTNING PROTECTION SYSTEM

MEASURED AT ANY POINT SHOULD NOT EXCEED 10 OHMS.

An appropriate number, sizing and spacing of IEGS-Ground Electrodes helps achieve a target

ground impedance of less than 10 ohms. To get such low impedance values, Soil Resistivity

Test of the site prior to designing of LPS is necessary. In IEGS, soil resistivity test by Wenner

method is carried out prior to designing of the LPS.

Deep driven

IEGS Ground Electrode



- 13 -

Parallel Earth Rods & Use of INDUS Electrical Grounding System-IEGS

Where ground conditions make deep driving of earth rods impossible, a matrix arrangement

of rods coupled to one another by conductors can be used. If possible, the earth rods must

be spaced at a distance at least equal to their driven depth.

If earth rods cannot be driven in a parallel line a INDUS –Electrical Grounding System (IEGS)

configuration can be used, ensuring that the spacing/depth ratio is still maintained. High

resistivity soil conditions can be overcome by backfilling earth rods with a suitable medium

such as INDUS Ground Conductivity Enhancing Material (GCEM) conductive concrete which

effectively increases the diameter of the earth rod and hence its surface area, thus lowering

resistance to earth.

Spacing of parallel

earth rod electrode

Example of side flashing

If the lightning protection system on a structure is hit by

lightning, then the current flowing through the system and

the resistance/impedance offered by the conductor path will

determine the magnitude of the potential difference seen by

the lightning conductors with respect to true earth.

The lightning conductors can, instantaneously, have a

potential magnitude of megavolts (1,000,000V) with respect

to true earth.

Typically, at instant of discharge:

Potential difference at A = 1,500,000V

Potential difference at B = 0V



- 14 -

BONDING (To Prevent Side Flashing)

It is important to keep the terminal contact resistance of a grounding wire to be lower than

0.1 ohms, to prevent melting during a lightning discharge, and the mass of copper in the

terminal contacts should be large to keep their temperature down. A 150g copper terminal

with 0.1 ohms contact resistance may melt during lightning discharge and provide no

protection at all. IEGS grounding copper terminals provide the right solution to this problem.

Bonding to prevent side flashing

1 Air termination

2 Down conductor

3 Bond to aerial

4 Bond to vent

5 Bond to re-bar

6 Bond to metal staircase7 Bond to metal window frame

8 Bond to vent pipe

9 Bond to steel door/frame

10 Test clamp

11 Indicating plate

12 Main earthing terminal of

electrical installation

13 Earth termination point

TEST PROCEDURES

After the grounding system is in place, the verification process begins. Verification testing

will ensure that the predicted ground system performance has been achieved. This validates

the design, installation and equipment manufacturer's warranty.

Although seemingly simple, conducting the test is often problematic, and the results are

frequently rendered invalid.

The most reliable post-installation testing procedure involves the Fall-of-Potential (Three-

Point) method. With the help of our Top of the Line digital ground resistance meter, we

measure resistance of the installed grounding system and then issue a CERTIFIFCATE for the

VALIDITY of measured resistance of the “Installed Electrical Grounding System” and LPS



- 15 -

SERVICES OFFERED

GROUND AUDIT Testing of Resistance values of the Existing Grounding

System & LPS and suggesting the rectifications if necessary.

SURVEY & SOIL RESISTIVITY TESTS Initial Survey of the New Sites for the

Electrical Ground Installation and carrying out the Soil Resistivity Tests.

DESIGNING OF LPS & ELECTRICAL GROUNDING SYSTEM using sophisticated

computer program to model the soil and grounding system and

recommending the quantity, type, length and shape of the ground rods,

including rod spacing and placement along with the LPS system components.

SUPPLY & INSTALLATION OF IEGS (INDUS-Electrical Grounding System) for

Human Safety, Equipment Protection and LPS.

TESTING AND VERIFICATION of the predicted Electrical Ground System

Performance and finally the issuance of Certificate.

SOIL RESISTIVITY TEST



- 16 -

LOW IMPEDANCE GROUNDING, SOMETIMES REQUIRE DEEP BORING

indus grounding & lightning protection system

Documents