All about amateur radio RF transmission lines. This relates to Section 26 of the NZART Radio Syllabus and may be used to teach this section of the exam.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
PROTECTION AGAINST OVER VOLTAGE AND GROUNDING Part 1Dr. Rohit Babu
Generation of overvoltages in power systems
Protection against lightning overvoltages
Valve type and zinc oxide lightning arresters
Insulation coordination
BIL
Impulse ratio
Standard impulse test wave
Volt-time characteristics
Grounded and ungrounded neutral systems
Effects of ungrounded neutral on system performance
Methods of neutral grounding
Solid
Resistance
Reactance
Arcing grounds and grounding Practices
study of lightning arrester ' working principal and working of lighning and construction of lightning arrester. and at the end what are the types of lightning arrester how these types are different from each other and what is their working principal and which is used mostly on 500kva substation.
All about amateur radio RF transmission lines. This relates to Section 26 of the NZART Radio Syllabus and may be used to teach this section of the exam.
IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com
PROTECTION AGAINST OVER VOLTAGE AND GROUNDING Part 1Dr. Rohit Babu
Generation of overvoltages in power systems
Protection against lightning overvoltages
Valve type and zinc oxide lightning arresters
Insulation coordination
BIL
Impulse ratio
Standard impulse test wave
Volt-time characteristics
Grounded and ungrounded neutral systems
Effects of ungrounded neutral on system performance
Methods of neutral grounding
Solid
Resistance
Reactance
Arcing grounds and grounding Practices
study of lightning arrester ' working principal and working of lighning and construction of lightning arrester. and at the end what are the types of lightning arrester how these types are different from each other and what is their working principal and which is used mostly on 500kva substation.
in this presentation i have completely described the basic constriction and working of Surge Arresters so that you will find it easy to understand and it can be easily delivered to the listeners
About Transmission Line.
Transmission Lines
Classification Of Transmission Lines
Overhead Power Line
Advantages Of Overhead Transmission Lines
Disadvantages Of Overhead Transmission Lines
Nominal “T” Method
Nominal “Pi” Model of a Medium Transmission Line
Underground Transmission Lines
Classification Of Underground Cables
Advantages Of Underground Cables
Disadvantages Of Underground Cables
Overvoltages are an increase of voltage on the electric line, measure between two conductors, which can produce damage on the installations
and the electric equipments.
There are two different types: transient and permanent.
Permanent or power frequency overvoltages are characterized by relatively long duration (several cycles) There are usually caused by:
- Defect connection of the neutral.
- Power consumption lowered.
Transient overvoltages are very short duration increases in voltage
between two conductors or between a conductor and the ground. They
can be on account of atmospheric electrical discharges (lightning), by
switching or by electrical faults (contact with earth or short circuit).
The presentation deals with principles of protecting buildings/structures and and power systems from effects of lightning.It also deals with protecting the power systems from over voltages arising from lightning and switching.
in this presentation i have completely described the basic constriction and working of Surge Arresters so that you will find it easy to understand and it can be easily delivered to the listeners
About Transmission Line.
Transmission Lines
Classification Of Transmission Lines
Overhead Power Line
Advantages Of Overhead Transmission Lines
Disadvantages Of Overhead Transmission Lines
Nominal “T” Method
Nominal “Pi” Model of a Medium Transmission Line
Underground Transmission Lines
Classification Of Underground Cables
Advantages Of Underground Cables
Disadvantages Of Underground Cables
Overvoltages are an increase of voltage on the electric line, measure between two conductors, which can produce damage on the installations
and the electric equipments.
There are two different types: transient and permanent.
Permanent or power frequency overvoltages are characterized by relatively long duration (several cycles) There are usually caused by:
- Defect connection of the neutral.
- Power consumption lowered.
Transient overvoltages are very short duration increases in voltage
between two conductors or between a conductor and the ground. They
can be on account of atmospheric electrical discharges (lightning), by
switching or by electrical faults (contact with earth or short circuit).
The presentation deals with principles of protecting buildings/structures and and power systems from effects of lightning.It also deals with protecting the power systems from over voltages arising from lightning and switching.
Lightning, Surge Protection & Earthing of Electrical & Electronic Systems in ...Living Online
Few topics generate as much controversy and argument as that of lightning and surge protection of electrical and electronic systems. Poor practices in earthing, and incorrect application and selection of lightning and surge protection devices can be the cause of continual and intermittent problems in a facility, often resulting in lost production and equipment failure.
This workshop looks at these issues from a fresh yet practical perspective and enables you to reduce expensive down time on your plant and equipment by the correct application of these principles. Essentially the workshop is broken down into the methods used to prevent lightning entering a facility such as dissipation arrays and those that divert surge energy away from sensitive equipment.
Dissipation systems are discussed with associated earthing systems. The unique properties of various surge protection devices are reviewed, enabling you to select the correct device suited to the application required. Earthing and surge protection for telecommunications and IT systems are examined in detail as well as the impact of lightning and simple techniques for minimising its impact.
MORE INFORMATION: http://www.idc-online.com/content/lightning-surge-protection-earthing-electrical-electronic-systems-industrial-networks-13?id=6987
A brief description about the components of the Distribution System. The components that are described below briefly are:-
1. Capacitor Voltage Transformer (CVT)
2. Current Transformer (CT)
3. Wave Trap
4. Isolators
5. Circuit Breakers
6. Surge arrester
7. Purpose of guard ring in suspension insulators
How to conduct the lightning impulse withstand test on 550kv GIS?Fang Sam
Abstract: With the rapid development of power grid in China, an increasing number of GIS are adopted in new substations. The lightning impulse test is recommended after the installation of GIS in order to check its insulation performance and reduce the risk of equipment failure. However, owing to the design and production, common lightning impulse generator with large capacitance load especially GIS cannot generate lightning impulse waveform, which meets the requirement. Therefore, based on lightning impulse withstand test of Three Gorges Right Bank 550kV GIS, models of lightning impulse generator and field equipment are established, and simulation calculation is done. According to the result, a method of installing the inductor in the impulse circuit is put forward to generate oscillating lightning impulse which meets the requirement of the test. This method is successfully applied in the test and results are good. Valuable experience has been accumulated for the lightning impulse test on GIS of 750kV, 1000kV substations in China. (http://www.himalayal.com/Impulse-Generator/HowtoConductLightningImpulseTestOnGIS.html)
Transients can cause slow degradation, erratic operation, or catastrophic failure in electrical parts, insulation dielectrics, and electrical contacts used in switches and relays. The possible occurrence of transients must be considered in the overall electronic design. Required circuit performance and reliability must be assured both during and after the transient
Lightning Characteristics and Impulse Voltage.Milton Sarker
Lightning characteristics and standard impulse
waveform are related to each other. But the lack
of realization about the relation between them
would make the solution to produce better
protection against lightning surge becomes
harder. Natural lightning surge waveform has
been compared to standard impulse waveform as
evidence that there have similarity between
them. The standard impulse waveform could be
used to test the strength of electrical equipment
against the lightning. Therefore designing and
simulating the impulse generator are the purpose
of this project beside to get better understanding
about lightning characteristics. This project aims
to develop an impulse generator circuit. The
main objectives of this work are two folds: the
first is the characterization of impulse voltages
and the second is the designing of an impulse
voltage generator. Our working purpose is to
give a concept about Impulse voltages and
impulse generator to the students and
researchers.
Light Triggering Thyristor for HVDC and other ApplicationsIDES Editor
High-power thyristors with direct light –triggering
and integrated protection functions can be utilized
advantageously for applications in which several thyristors are
connected in series. This applies in particular to High-Voltage
DC (HVDC) transmission, Static Var Compensation (SVC),
converters for medium voltage drives, and also to certain pulse
power applications. Recent progress in both device innovations
and optimization of some application systems is reviewed in
this article.
Implicitly or explicitly all competing businesses employ a strategy to select a mix
of marketing resources. Formulating such competitive strategies fundamentally
involves recognizing relationships between elements of the marketing mix (e.g.,
price and product quality), as well as assessing competitive and market conditions
(i.e., industry structure in the language of economics).
Personal Brand Statement:
As an Army veteran dedicated to lifelong learning, I bring a disciplined, strategic mindset to my pursuits. I am constantly expanding my knowledge to innovate and lead effectively. My journey is driven by a commitment to excellence, and to make a meaningful impact in the world.
Premium MEAN Stack Development Solutions for Modern BusinessesSynapseIndia
Stay ahead of the curve with our premium MEAN Stack Development Solutions. Our expert developers utilize MongoDB, Express.js, AngularJS, and Node.js to create modern and responsive web applications. Trust us for cutting-edge solutions that drive your business growth and success.
Know more: https://www.synapseindia.com/technology/mean-stack-development-company.html
Buy Verified PayPal Account | Buy Google 5 Star Reviewsusawebmarket
Buy Verified PayPal Account
Looking to buy verified PayPal accounts? Discover 7 expert tips for safely purchasing a verified PayPal account in 2024. Ensure security and reliability for your transactions.
PayPal Services Features-
🟢 Email Access
🟢 Bank Added
🟢 Card Verified
🟢 Full SSN Provided
🟢 Phone Number Access
🟢 Driving License Copy
🟢 Fasted Delivery
Client Satisfaction is Our First priority. Our services is very appropriate to buy. We assume that the first-rate way to purchase our offerings is to order on the website. If you have any worry in our cooperation usually You can order us on Skype or Telegram.
24/7 Hours Reply/Please Contact
usawebmarketEmail: support@usawebmarket.com
Skype: usawebmarket
Telegram: @usawebmarket
WhatsApp: +1(218) 203-5951
USA WEB MARKET is the Best Verified PayPal, Payoneer, Cash App, Skrill, Neteller, Stripe Account and SEO, SMM Service provider.100%Satisfection granted.100% replacement Granted.
Enterprise Excellence is Inclusive Excellence.pdfKaiNexus
Enterprise excellence and inclusive excellence are closely linked, and real-world challenges have shown that both are essential to the success of any organization. To achieve enterprise excellence, organizations must focus on improving their operations and processes while creating an inclusive environment that engages everyone. In this interactive session, the facilitator will highlight commonly established business practices and how they limit our ability to engage everyone every day. More importantly, though, participants will likely gain increased awareness of what we can do differently to maximize enterprise excellence through deliberate inclusion.
What is Enterprise Excellence?
Enterprise Excellence is a holistic approach that's aimed at achieving world-class performance across all aspects of the organization.
What might I learn?
A way to engage all in creating Inclusive Excellence. Lessons from the US military and their parallels to the story of Harry Potter. How belt systems and CI teams can destroy inclusive practices. How leadership language invites people to the party. There are three things leaders can do to engage everyone every day: maximizing psychological safety to create environments where folks learn, contribute, and challenge the status quo.
Who might benefit? Anyone and everyone leading folks from the shop floor to top floor.
Dr. William Harvey is a seasoned Operations Leader with extensive experience in chemical processing, manufacturing, and operations management. At Michelman, he currently oversees multiple sites, leading teams in strategic planning and coaching/practicing continuous improvement. William is set to start his eighth year of teaching at the University of Cincinnati where he teaches marketing, finance, and management. William holds various certifications in change management, quality, leadership, operational excellence, team building, and DiSC, among others.
VAT Registration Outlined In UAE: Benefits and Requirementsuae taxgpt
Vat Registration is a legal obligation for businesses meeting the threshold requirement, helping companies avoid fines and ramifications. Contact now!
https://viralsocialtrends.com/vat-registration-outlined-in-uae/
Event Report - SAP Sapphire 2024 Orlando - lots of innovation and old challengesHolger Mueller
Holger Mueller of Constellation Research shares his key takeaways from SAP's Sapphire confernece, held in Orlando, June 3rd till 5th 2024, in the Orange Convention Center.
"𝑩𝑬𝑮𝑼𝑵 𝑾𝑰𝑻𝑯 𝑻𝑱 𝑰𝑺 𝑯𝑨𝑳𝑭 𝑫𝑶𝑵𝑬"
𝐓𝐉 𝐂𝐨𝐦𝐬 (𝐓𝐉 𝐂𝐨𝐦𝐦𝐮𝐧𝐢𝐜𝐚𝐭𝐢𝐨𝐧𝐬) is a professional event agency that includes experts in the event-organizing market in Vietnam, Korea, and ASEAN countries. We provide unlimited types of events from Music concerts, Fan meetings, and Culture festivals to Corporate events, Internal company events, Golf tournaments, MICE events, and Exhibitions.
𝐓𝐉 𝐂𝐨𝐦𝐬 provides unlimited package services including such as Event organizing, Event planning, Event production, Manpower, PR marketing, Design 2D/3D, VIP protocols, Interpreter agency, etc.
Sports events - Golf competitions/billiards competitions/company sports events: dynamic and challenging
⭐ 𝐅𝐞𝐚𝐭𝐮𝐫𝐞𝐝 𝐩𝐫𝐨𝐣𝐞𝐜𝐭𝐬:
➢ 2024 BAEKHYUN [Lonsdaleite] IN HO CHI MINH
➢ SUPER JUNIOR-L.S.S. THE SHOW : Th3ee Guys in HO CHI MINH
➢FreenBecky 1st Fan Meeting in Vietnam
➢CHILDREN ART EXHIBITION 2024: BEYOND BARRIERS
➢ WOW K-Music Festival 2023
➢ Winner [CROSS] Tour in HCM
➢ Super Show 9 in HCM with Super Junior
➢ HCMC - Gyeongsangbuk-do Culture and Tourism Festival
➢ Korean Vietnam Partnership - Fair with LG
➢ Korean President visits Samsung Electronics R&D Center
➢ Vietnam Food Expo with Lotte Wellfood
"𝐄𝐯𝐞𝐫𝐲 𝐞𝐯𝐞𝐧𝐭 𝐢𝐬 𝐚 𝐬𝐭𝐨𝐫𝐲, 𝐚 𝐬𝐩𝐞𝐜𝐢𝐚𝐥 𝐣𝐨𝐮𝐫𝐧𝐞𝐲. 𝐖𝐞 𝐚𝐥𝐰𝐚𝐲𝐬 𝐛𝐞𝐥𝐢𝐞𝐯𝐞 𝐭𝐡𝐚𝐭 𝐬𝐡𝐨𝐫𝐭𝐥𝐲 𝐲𝐨𝐮 𝐰𝐢𝐥𝐥 𝐛𝐞 𝐚 𝐩𝐚𝐫𝐭 𝐨𝐟 𝐨𝐮𝐫 𝐬𝐭𝐨𝐫𝐢𝐞𝐬."
1. Abstract—Distribution substations feed power to the actual
consumers through distributors and service lines. The main
equipments are generators and transformers. To protected these
equipments and for stability purpose, over-voltages and over currents
protection are important to consider. Lightning is one of the most
serious causes of over-voltage. If the power equipments especially at
outdoor substation are not protected, the over-voltage will cause
burning of insulation. Lightning arrester can protect the damages of
equipments. This paper describes the arrester type, lightning terminal
and earthing plan of Dagon East substation in Myanmar. DynaVar
station class and intermediated arrester (Vrated = 72kV and I charge
(max) = 10kA) are used in this substation. Most of substation
equipments are designed to match with the insulation coordination. If
the insulation equipments are higher, the cost is also high. So, to
relax this, the lightning arrester must be put in front of the protected
equipments and protected zone. For this purposes, this paper
specially indicates the safety and saving cost of equipments for over-
voltage protection in distribution substation.
Keywords—Lightning arrester, Earthing plan, DynaVar station,
Intermediated arrester.
I. INTRODUCTION
UBSTATION design involves more than installing
apparatus, protective devices and equipment. The
significant momentary investment and required reliable
continuous operation of the facility requires detailed attention
to preventing surges from entering the substation facility. The
effects of disturbances with limiting in a power system, which
if allow to persist, may damage plant and interrupt the supply
of electrical energy. Lightning is one of the most serious
causes of over voltage. If the power equipment especially at
outdoor substation is not protected the over-voltage will cause
burning of insulation. Thus it results into complete shutdown
of the power and the loss may run into cores of kyat. Electrical
equipment can be damage due to over-voltage such as
switching surge over-voltage, Lightning surge over-voltage,
transient recovery voltage and power frequency temporary
over-voltage in transmission line and receiving end of
substation. It is important to protect power equipment against
them wherever possible, consistent with sound economic.
Lightning Arrester can protect the damages of electrical
equipments. So, Lightning Arrester needed to install in the
terminal end of the transmission line, substation, high voltage
Miss NayKyiHtwe is a student of Mandalay Technological University.
(e-mail :naykyihtwe08@ gmail.com).
transformers and low voltage transformer. The analysis of
electromagnetic transient is depended on operating voltage,
lengths of the lines and contactor configuration. So, it can be
chosen correctly the technical specifications of the apparatus
of Lightning Arrester base on the amounts of receiving over-
voltage.
II. PHYSICAL PHENOMENON OF LIGHTNING
Lightning is a huge spark caused by the electrical discharge
taking place between the clouds, within the same cloud and
between the clouds and the earth. The turmoil that is apparent
inside a thundercloud is most impressive to the viewer. It
shape changes continually, and one notes especially the
development of the towering ‘thunderhead’. It is very easy to
imagine the fierce updrafts with the cloud and the downdrafts
near it surface which are matters of practical experience for
aviators. It is generally accepted that the updraft is responsible
for charge separation within the cloud, like some gigantic
electrostatic generator, which leads to the creation of electric
fields within and around the cloud and ultimately to the
electric breakdown that is called lightning.
III. WAVE SHAPE OF LIGHTNING STROKE
The lightning stroke current rises to crest value very quickly
and then starts decaying at a low rate as illustrated in Figure.1.
The generalized wave shape can be characterized as:
1. Crest or peak value and it have been observed that
the maximum value of this current is 400 kA.
2. The wave front line varies from 1 t 10 sec.
3. The time at which the stroke current reduces to 50
percent value of that crest value and it has been
estimated that the time varies from 10 to 100 sec.
Figure.1 Generalized wave shape of lightning stroke
Analysis and Design Selection of Lightning
Arrester for Distribution Substation
Nay Kyi Htwe
S
World Academy of Science, Engineering and Technology 48 2008
174
2. IV. STATIC CHARGING OF THE CONDUCTOR DUE TO A
CHARG CLOUD
Suppose that the cloud is positively charged, then the line
will be charged to a negative potential by the electrostatic
induction. This negative charge will be present right under the
cloud and the portions of the line away from this point will be
charge positively as illustrated in Figure.2.
Figure.2 Static charging of the line due to a cloud
The charge on the line will not flow since it is a bound
charge. The positive charge on the far ends of the line will
however leak to the earth slowly through insulators metallic
parts etc, thus leaving only the negative charge on the line.
Due to a direct discharge occurring between this cloud and
another passing by cloud the charge on the cloud is neutralized
then the charge on the line is no more a bound charge and is
free to travel in both directions in the form of traveling waves.
V. OVERVOLTAGE DUE TO LIGHTNING STROKE
In case of direct strokes, a line having a surge impedance of
Zs and the discharge current be Id, then the over-voltage due to
a direct stroke is
sdd ZIV ×= (1)
When the traveling waves flow in one direction, the
equation is true. However, when they travel in both directions,
the current is halved and the over-voltage is
2
ZI
V sd
d
×
= (2)
When the lightning stroke is on the earth wire or top of a
tower, the over-voltage is
t
i
ccdd
d
d
lZIV +×= (3)
Where Z c is the impedance of the earth conductor and l c is
the inductance of the line conductor.
VI. INTERACTION BETWEEN LIGHTNING AND THE POWER
SYSTEM
When lightning strikes a power line, a current is injected
into the power system. This is very useful concept. This
current will give rise to depend upon its wave shape and the
impedances through which it flows. If a tower is struck, the
impedance of the tower will be of concern. The voltage drop
down the tower will appear across the line insulation. If this is
excessive, flashover of the insulation will occur and a fault will
be placed on the system.
The current comings into a tower have been postulated by
lightning stroke from a cloud, and then disappear into the
ground. A useful concept is to think of the cloud and earth as
forming a vast capacitor which is being discharge by the
stroke. The return circuit would be completed by displacement
current in the electric field. This is suggested by Figure.3.
Stroke
Earth
cloud
Figure.3 Lightning stroke from cloud to earth discharges a
vast Capacitor
VII. LIGHTNING ARRESTER
Lightning arresters are the most effective means of
protecting an electrical apparatus against traveling voltage
waves caused by lightning and switching. Lightning arresters
are connected across and apparatus to provide a Low-
resistance path to ground, thus limiting the transient voltages
below the Basic Impulse Level of the apparatus. There are four
different classes of arrester.
1. Station
2. Intermediate
3. Distribution, and
4. Secondary
The functions of a lightning arrester are
1. To act like an open circuit during the normal
operation of the system i.e., to hold off the system
voltage,
2. To limit the transient voltage to a safe level with
the minimum delay and fitter, and
3. To bring the system back to its normal operation
mode as soon as the transient voltage is
suppressed, i.e., to interrupt the power-follow
current and to reseal itself.
The normal operation or operational mode includes the
system under faulted condition. Under several types of system
faults, such as the single line-to-ground faults, the voltage to
ground across the unfaulted phases will rise above the normal
voltage level. The arrester must not go into conduction during
this fault condition. It should also be able to interrupt the
power-follow current and reseal itself under system fault
conditions when the power-frequency voltage across it rises.
VIII. SELECTION OF LIGHTNING ARRESTER
The lightning arresters are designated by the crest
magnitude of the discharge current having 10×20 second
wave shape which the arrester can safely pass without damage.
The lightning arresters are designated as 8, 10, 20 KA. They
World Academy of Science, Engineering and Technology 48 2008
175
3. can safely discharge these current crests. As the arrester is a
protective device, if is a general impression that if should be
rated for most severe conditions of discharge currents says 20
A. The discharge current from the arrester varies from a few
hundred amperes to kilo-amperes and sometimes if is even 20
KA. Maximum discharge voltage and discharge factor for the
arrester is defined the maximum value of voltage which
appears across the arrester terminals at the time of discharging
if rated current determines its impulse level of protection. The
discharge factor if is,
DF=
arrestertheofvalue)(RMSvoltageRated
arrestertheofvalue)(crestvoltagedischarge
(5)
In the early designs of arresters, this discharge factor was
quite high (about 5.6) but due to the advent of better material
and Modern research it has been reduced varying to 2.4 to 3.0.
The above ratio for arresters manufactured by different firms
varies from 1.5 to 1.7, so, the average value may be taken as
1.6 E is the rated arrester voltage KV (R.M.S) and LS is the
minimum impulse insulation level in kV (crest valve) its value
after allowing 10% as tolerance factor and 25% as margin
factor can be obtained.
LS= E
0.8
21.61.11.25 ×××
=3.88E (6)
In case Extra High Voltage system LP in kV,
LP = 2.3 × power frequency withstand voltage in kV (RMS)
= 2.3 × EL (7)
For 75% arrester,
LP = 2.37 EL (8)
For 80% arrester,
LP=2.53EL (9)
IX. EARTHING SYSTEM
The frame of every generator, stationary motor, and so far
as particable, portable motor, and metallic parts of all
transformer and regulating and controlling apparatus
connected with supply shall be earthed by the owner by
separate and distinct connection with earth.
Every conductor used on earthing shall be of stranded as
solid copper or suitable copper alloy, and shall be protected
wherever liable to mechanical damage and also, where
necessary, against corrosion, particular attention being given in
these respects to the earthing leads at its point of connection
with the earth electrode. The coefficient of earthing is below
80 percent. On four wire distribution systems, with solidly
ground transformer neutral at every voltage level, coefficient
of earthing is generally less than 80%. On high voltage
transmission systems the coefficient of earthing does not
exceed 75%.
In resistance of Common Types of Earth-electrode, there are
three types.
1. Plates
2. Pipes and rods
3. Strip or conductor electrodes
X. INTERMEDIATE CLASS DYNAVAR ARRESTER
Application is based upon the maximum continuous
operation voltage, line to neutral, at the arrester location. For
grounded neutral systems, this is computed as maximum
system voltage divided by √3. For historical comparison, the
maximum continuous operating voltage is 81% of the
conventional 71% arrester installed on an affectively grounded
neutral system.
Figure.4 Section view of typical unit
A. Lightning Arrester Design
At Dagon East substation, DynaVar station class and
intermediate surge arresters are used. The system voltage is 66
kV and maximum continuous operation voltage is 48 kV rms.
The duty cycle rating is 60 kV rms and maximum discharge
current is 10 kA.
1. Maximum 0.5µs discharge voltage = 163.5 kV
2. Maximum switching surge protective level=116.4 kV
3. Maximum discharge voltage using an 8/20=148.8 kV
Current wave-kV
The maximum discharge voltage for a10kA impulse current
wave produces a voltage wave cresting in 0.5µs.
B. Structure of Lightning Arrester
In Figure.5, PVN 48.0kV maximum continuous operation
voltage arrester is shown. It has 0.56 diameter holes, clamp
type terminal, arrester name plate. Its internal diameter is 9.3
diameters.
Figure.5 PVN 48.0 kV maximum continuous operation
voltage Arrester
9.3
1.7
Clamp Type Terminals Suitable
for Use with CU DR AL
Conductor 0.25 to 0.81 Dia
0.56 Dia 3 Holes at
120˚ On 10.0 Dia BC
1.750.56
Diameter 4
Holes
Arrester Nameplate
32.
3
World Academy of Science, Engineering and Technology 48 2008
176
4. C. Specification of Lightning Arrester for Incoming Side
Incoming side of Dagon East substation, the
specifications of lightning arrester are as follow.
Figure.6 One Line Diagram of East Dagon 30MVA
Substation
System nominal voltage = 66kV
Rated normal Voltage = 66 × 1.1 = 72.6kV
Continuous Operating Voltage (kV) rms = 48.0kV
Normal Discharge Current (8 /20µs) kA = 10kA
1/50 Impulse Spark over Voltage = 163.5kV
Frequency (Hz) = 50Hz
Type = outdoor
D. Specifications of Lightning Arrester for Outgoing Side
The followings are the specifications of lightning arrester
for outgoing side of Dagon East substation.
System nominal voltage = 33kV
Rated normal Voltage = 33 × 1.1 = 36kV
Continuous Operating Voltage (kV) rms = 24kV
Normal Discharge Current (8 /20µs) (kA) = 10kA
Frequency (Hz) = 50Hz
Type = outdoor
XI. LIGHTNING EARTHING
In earthing system, lightning arresters with PVC coated
wire and cable lug are used.
1. 66kV Lighting Arrester(70mm2
PVC Coated Wire)
= 50'
2. 33kV Lighting Arrester(70mm2
PVC Coated Wire)
= 100'
3. 70mm2
Cable Lug = 2 No
Figure.7 shows the earthing plan of Dagon East substation.
XII. DETAILED DESIGN DATA
For incoming side and outgoing side, the discharge
voltage, insulation level, minimum impulse insulation level
and power frequency withstand voltage base on 100% arrester
are as shown in Table.1. Ground voltage peak value and
switching surge withstand voltage are also shown in Table.1.
Table.1. Detailed Design Data Sheet
System
Voltage
66kV for
Incoming Side
33kV for
Outgoing Side
Rated Voltage (kV) 72.6 36
Discharge Voltage
on 100% Arrester (kV)
188.76 93.6
Insulation Level for
100% Arrester (kV)
284.78 164.4
Minimum Impulse
Insulation Level on
100%(kV)
732.389 363.168
Power Frequency
withstand Voltage on
100% (kV)
151.8 75.9
Ground Voltage
Peak Value(kV)
59.28 29.63
Require Switching
Surge Withstand
Voltage (kV)
215.6 107.8
XIII.CONCLUSION
In this paper, the basis theory of lightning, lightning
shielding and design of lightning arrester are presented.
DynaVar station class and intermediate arresters are used. The
type of arrester is outdoor type. The rated voltages of arresters
are 72kV and 36kV, the maximum discharge current is 10kA
and MCOV are 48kVrms and 24kVrms. The lightning arrester
in this paper is provided for overvoltage protection in
distribution substation. This paper will help and give the
electrical knowledge of the protection system in distribution
substation which coach to the technicians, the professional
engineers, the students who facing the overvoltage condition
and protection coordination of distribution substation.
ACKNOWLEDGMENT
Firstly, the author would like to express her indebtedness
and gratitude to her beloved parents, for their kindness,
support, understanding during the whole course of this work
and encouragement to attain ambition without any trouble. The
author is indebted to all her teachers who give her knowledge
from M.T.U and Y.T.U in Myanmar.
REFERENCES
[1] Allan Greenwood 1923 “Electrical Transients in Power System”
Second Edition, John Willey & Sons, Inc
[2] Anderson 1987 “Transmission Line Reference Book”, Second
Edition Substations Committee
[3] ANSI/ IEEE 1989 ” IEEE Standard for Gapped Silicon-Carbide
Surge Arresters for AC Power Circuit”
[4] Franked- Graham 1970 “New Electric Library” Vol-2
[5] IEEE Std 998- 1996 “Guide for Direct Lightning Stroke Shielding of
Substation”, IEEE Working Group D5,
[6] U Tin Swe “Power System Analysis Part 3”
World Academy of Science, Engineering and Technology 48 2008
177
5. Figure.7 Dagon East Sub-station Earthing Plan
66kV TR:
30 MVA
R = 2
66kV LA
66kV Switch
Yard
33kV LA
33kV TR:
10 MVA
100kVA
Transformer
Switch Gear Panel Earth Ring System
10MVA×R
Neutral Earth
100VA
Neutral Earth
Lightning
Arrester
Lightning
Arrester
Body Earth
LA Earth
LA Earth
DS Earth
R = 1.8
2 Pole DS LA PT CT CB CB CT PT DS
CB CT PT DS
10´ 10´ 10´ 10´ 10´ 10´ 10´ 10´ 10´ 10´ 10´10´ 10´10´ 10´
R = 2
Lightning Earth
R = 2 R = 2
Lightning Earth
30MVA
Body
Earth
30MVA×
R
World Academy of Science, Engineering and Technology 48 2008
178