International Journal of Electrical and
Electronics Engineering Research (IJEEER)
IS S N(P): 2250-155X; IS S N(E): 2278-943X
Vol. 4, Issue 4, Aug 2014, 47-54
© TJPRC Pvt. Ltd.
EFFECT OF VOLTAGE ON CONDUCTING PARTICLE MOVEMENT IN SINGLE PHASE
GAS INSULATED BUSDUCT USING ANALYTICAL METHOD AND CSM CONSIDERING
WITH AND WITHOUT IMAGE CHARGES
A. GIRIPRASAD1 , J. AMARNATH2 & POONAMUPADHYAY3
1
2
St. Peter‟s Engineering College, Hyderabad, Andhra Pradesh, India
Jawaharlal Nehru Technological Universities, Kukatpally, Hyderabad , Andhra Pradesh, India
3
VNR Vignan Jyothi Institute of Engg and Technology, Hyderabad, A ndhra Pradesh, India
ABSTRACT
As power consumption in urban areas is increasing, a large number of Gas Insulated Substations have been
constructed. Compact and cost effective solutions are required for substations installed in areas where space availability is
limited. Safety and the avoidance of fire accidents are the most important considerations for substations installed in urban
areas. In this context, Gas Insulated Substations have found a broad range of applications in power systems for more than
forty
years
because
of
their
high
reliability, easy
maintenance
and
small ground
space
requirement.
This paper mainly concentrates on comparing the effect of voltage on conducting particle movement in single phase gas
insulated busduct using analytical method and charge simulation method considering with and without image charges.
The simulation studies in this paper shows that the maximum radial movements for Al and Cu particles computed with
image charge effect are relatively more than without image charge effect. The results has been presented and analyzed .
KEYWORDS: Voltage, Gas Insulated, Electrical Insulation
INTRODUCTION
The invention of SF6 insulation gas has revolutionized not only the technology of circuit breakers but also the
organization of electrical power transmission lines and substations. The dielectric strength of SF6 gas at atmospheric
pressure is approximately three times more than air. It is incombustible, non toxic, colorless, chemically inert and has very
good current interruption and arc-quenching properties. It has been studied that 80% of Sulphur Hexafluoride gas produced
in this world is used for GIS. Gas Insulated Substation (GIS) is a compact, multi-component assembly enclosed in a
grounded metallic housing in which the primary insulating medium is compressed Sulphur hexafluoride (SF6) gas.
In Gas Insulted Substations Sulphur Hexafluoride gas is used as insulation between the active and non -active components
of GIS. Because of GIS the clearance distances are dramatically reduced and greater d esign flexibility is provided.
Gas Insulated Substations can be installed in congested urb an areas, places where space is available at premium rate,
underground, beneath commercial buildings, parks and public spaces, closely built -up industrial areas and mountain areas
where site preparation is difficult, at high altitudes and in places where s now and ice are problems existing.
Free metallic particles of different sizes and shapes are usually present on the inner surface of the outer
enclosure of Gas Insulated Busduct (GIB) or Gas Insulated Systems (GIS). Usually, there is less affect on dielectric
strength of GIB with the particles which remain fixed to an insulating or energized surface [1]. But if particles can move
www.tjprc.org
editor@tjprc.org
A. Giriprasad, J. Amarnath & Poonam Upadhyay
48
under the influence of electric field produced by charged inner conductor of GIB/GIS then the free conducting
particles gets charged when they are in contact with GIB enclosure and once if they get sufficient charge and local electric
field, these particles lift from its position and move into inter electrode gap. If these moving charged particles come near to
live GIB inner conductor its distance critically affects the breakdown voltage.
Initially the small gap between the
particle and the inner conductor breaks down followed by a breakdown between particle and outer enclosure gap of
GIB.
If the metallic particle movement‟s pattern can be predicted then the probability of flashover due to moving
particle in Gas Insulated Busduct can be computed.
With this, the flashover probabilities of different types of
contaminated free metallic particles in Gas Insulated Busduct can be estimated. So, Unraveling the various forces
acting on a contaminated metallic particle in Gas Insulated Busduct (GIB) is very important for analyzing it‟s the random
behavior. An appropriate mathematical model of the contaminated free conducting particle mo tion in a Gas Insulated
Busduct has been derived by analyzing different charging mechanisms of metallic particles resting on the bare inner
surface of outer enclosure.
As the voltage of inner conductor increases the electric field around the metallic particle resting on bare
inner surface of outer enclosure of GIB also increases and the particle which is at rest gets charge gradually.
The charge acquired by the particle depends on physical size, shape, orientation of the metallic particle and th e local
electrical field.
At particular voltage of inner conductor the force on free conducting particle due to electrostatic
force exceeds the gravitational and drag forces acting on the particle and it moves into inter electrode gap of Gas
Insulated Busduct.
This decreases the distance between charged particle and inner live conductor and causes the
breakdown of insulation through flashover. So, interpreting various types of particle charging methods for deriving
mathematical equation for finding the particle trajectory in Gas Insulated System is very much essential. For a metallic
particle, the minimum electrical field required i.e., lift-off field to rise from the resting position can be calculated in case of
a bare electrode system by simple approximations.
From the experiments conducted on spiral particles [2] can be realized that it is more difficult to find the lift-off
field, because, the first lift-off field value of results is remarkably higher than following values. The experimental results
obtained by Parekh et al. [3] are revealing that the variance and mean value of the lift-off field is significantly reduced by
processing the electrodes for several hours with constant power supply.
The work reported in this paper covers the calculation the electric field of conducting particle movement in single
phase gas insulated busduct using analytical method and charge simulation method considering with and without image
charges.
ELECTRIC FIELD CALCULATION IN SINGLE PHASE GAS INSULATED BUSDUCT USING
ANALYTICAL METHOD
Figure 1: Single Phase Gas Insulated Busduct with Metallic Particle Resting on Inner Surface
Impact Factor (JCC): 5.9638
Index Copernicus Value (ICV): 3.0
49
Effe ct of Voltage on Conducting Particle Movement in Single Phase Gas Insulated
Busduct Using Analytical Method and CSM Considering with and with out Image Charges
Using analytical method the electric field „E(t)‟ at time instant ‟t‟ in Gas Insulated Busduct at point „P‟ as shown
in figure 1 is,
(1)
Where,
is the supply voltage of inner conductor GIB,
- Inner radius of outer enclosure
- Inner conductor radius and y(t) - the inner surface of enclosure to upward moving metallic particle.
FIELD CALCULATION IN SINGLE PHASE GAS INSULATED BUSDUCT USING CHARGE
SIMULATION METHOD
The figure 2 shows the basic concept of applying charge simulation method without considering image charges of
fictitious charges inner conductor of GIB [4-14].
Figure 2: Basic Concept of Charge Simulation Method without Image Charges
The electrostatic field „E‟ at point „P(x,y)‟ without image charge is calculated by using the following equations:
E x (t ) 
i

i  j 12
n
(Re/ d )( x  x j ) 

x  xi

3

2
2
2
2
 ( x  xi )  ( y  yi ) 3 ( x  x j )  ( y  y j ) 

  i
i 1 2
n
Ex
Ey

i

i 1 2
n
x  xi


3
2
2 
 ( x  xi )  ( y  y i ) 
(2)
y  yi


3
2
2 
 ( x  x i )  ( y  y i ) 
(3)
Where Ex(t), Ey(t) are Electrostatic field components at time instant „t‟ along X(Horizontal) and Y(Vertical)-axes
respectively, x, y are coordinates of point „P‟ where Electric field is to be ca lculated, xi, yi are coordinates of ith fictitious
charge, „n‟ is the total number of fictitious charges, λi is line charge density of ith fictitious charge.
www.tjprc.org
editor@tjprc.org
A. Giriprasad, J. Amarnath & Poonam Upadhyay
50
The following figure 3 shows the basic concept of Charge Simulation method with image charges for calculating
electric field intensity at point „p‟:
Figure 3: Basic Concept of Charge Simulation Method with Image Charges
The Electrostatic field at point „p(x,y)‟ without image charge is calculated by using the following equations:
E y (t ) 
n
i
 2
i  j 1
(Re/ d )( y  y j ) 

y  yi

3

2
2 3
2
2
 ( x  xi )  ( y  yi ) ( x  x j )  ( y  y j ) 
(5)
Where xj, yj are coordinates of jth image charge and „d‟ is distance from conductor center to fictitious charge.
Solving the above equation gives the radial movemen t of moving metallic particle. But the particle geometric
configuration of the tips is generally uneven and the movement of the particle is not unidirectional. So, the particle also
moves in axial direction because of particle surface roughness at the tips and randomness of this axial movement can be
reasonably simulated by using Monte-Carlo technique [17-18].
RESULTS AND DISCUSSIONS
Table 1: Maximum Radial Movement of Al and cu Particle (l=12mm, r=.25mm) at Various Power Frequency
Voltages
Impact Factor (JCC): 5.9638
Index Copernicus Value (ICV): 3.0
51
Effe ct of Voltage on Conducting Particle Movement in Single Phase Gas Insulated
Busduct Using Analytical Method and CSM Considering with and with out Image Charges
Table 2: Maximum Axial Movement of Al and Cu Particle (L=12mm, R=.25mm) at Various Power Frequency
Voltages
Figure 4: Maximum Radial Movement of Al Particle at Voltages Ranging From (75- 400) kV Using AM, CSM with
and without Image Charges
Figure 5: Maximum Axial Movement of Al Particle at Voltages Ranging From (75- 400) kV Using AM, CSM with
and without Image Charges
Simulation of Aluminum and Copper metallic particles movement patterns and maximum radial and axial
movements requires thorough understanding of particle charging mechanisms and particle dynamics in single phase
isolated conductor and Gas Insulated Busduct. Electric field has great influence on particle movement and this electric field
at the particle location at every time instant is computed using analytical, charge simulation separately.
www.tjprc.org
editor@tjprc.org
A. Giriprasad, J. Amarnath & Poonam Upadhyay
52
The maximum radial and axial movements of Aluminum and Copper particles in single phase isolated conductor
Gas Insulated Busduct are given in tables 1 and 2 for particle sizes of length 12mm and radii 0.25mm at (75-400) kV
voltages.
The movements given in tables are obtained with different field calculation methods such as analytical, charge
simulation methods. The movement patterns of Al and Cu particles in single phase GIB obtained with different field
calculation methods are shown in figure 4 & 5 at different voltages.
From the results it can be observed that the Al and Cu particle movements are increasing with increase of applied
voltage. It is also observed that maximum radial movements are almost equal when electric fields are calculated using
analytical, charge simulation methods It is also noted that maximum radial movements for Al and Cu particles computed
with image charge effect are relatively more than without image charge effect.
From the results it is found that the maximum axial movements of Al and Cu particles are generally increasing
with increase of voltage but sometimes decreasing with increase of voltage because of random behavior of the particle.
CONCLUSIONS
When electrostatic force exceeds the drag and gravitation forces the particle lifts up which is resting on the
enclosure surface. A two dimensional mathematical model has been formulated to simulate the movement of horizontal
wire like particle, When the particle is subjected to electric field by applying voltage. If the applied voltage is increased
after the lift of voltage, the particle moves into the gap between enclosure and conductor in the applied electric field
direction, the metallic particle equation is solved by using RK 4 th order method gives only radial movement of the particle
that‟s why Monte-control technique is also used to obtain both radial and axial movements by considering solid angle of 1 0
from vertical. Probability of flash over between enclosure and conductor is increased with maximum movement of the
particle.
After analyzing the results, it has been observed that the movement of the particle using CSM is less than that of
Analytical method. The movement of Al particle is greater than that of Cu particle in both Analytical method and CSM.
The voltage and electric field required is reduced to lift the particle resting on the enclosure by considering image charge
effect because electric force acting on the particle is almost doubled. The particle movement is increased by considering
image charge. The metallic particle contamination movement is almost doubled by considering image charge.
REFERENCES
1.
M. Eteiba, et al., “Influence of a conducting particle attached to an Epoxy Resin Spacer on the Breakdown
Voltage of Compressed-Gas Insulation”, Gaseous Dielectrics II, Editor: L. G. Christophorou, Pergamon Press,
1980.
2.
O. Yamarnoto. T Hara. K Hashimoto, Y. Tokko, T. Fujimoto; “Behaviour of a Metal Particle on a Coated
Electrode Affected by Corona Charge”
3.
Parekh. H, Srivastava. K. D, Van Heeswijk, R.G, 1979, “Lifting field of free conducting particles in compressed
SF6 with dielectric coated electrodes”, IEEE Transactions, Vol. PAS –98, pp. 748-755.
Impact Factor (JCC): 5.9638
Index Copernicus Value (ICV): 3.0
53
Effe ct of Voltage on Conducting Particle Movement in Single Phase Gas Insulated
Busduct Using Analytical Method and CSM Considering with and with out Image Charges
4.
M. S. Abou-Seada and E. Nasser, “Digital computer calculation of the electric potential and field of a rod gap”,
Proc. IEEE, Vol. 56, No. 5, 1968, pp. 813-820.
5.
M. S. Abou-Seada and E. Nasser, “Digital computer calculation of the potential and its gradient of a twin
cylindrical conductor”, IEEE Trans. PAS, Vol. 88, 1969, pp. 1802-1814.
6.
M. M. A. Salama and R. Hackam, “Voltage and electric field distribution and discharge inception voltage in
insulated conductors”, IEEE Trans. PAS, Vol. 103, NO. 12, 1984, pp. 3425-3433.
7.
H. Singer, H. Steinbigler and P. Weiss, “A charge simulation method for the calculation of high voltage fields”,
IEEE Trans. PAS, Vol.93, 1974, pp. 1660-1668
8.
S. Sat0 and S. Menju, “Digital calculation of electric field by charge simulation method using axispheroidal
charges”, Electrical Engineering in Japan, Engineering in Japan, Vol. 100, NO. 2, 1980, pp. 1-8.
9.
M. R. Iravani and M. R. Fbghuveer, “Accurate field solution in the entire inter electrode space of a rod-plane gap
using optimized charge simulation”, IEEE Trans. Electrical Insulation, Vol. 17, No. 4, 1982, pp. 333-337.
10. P. K. Mukherjee and C. K. Roy, “Computation of electric field in a condenser bushing by using fictitious area
charges”, 4th ISH Symposium, Athens, 1983, paper 12. 09.
11. Mohsen, “Justification of the charge simulation technique and its applications”, Proc. IEEE Canadian
Communication and Power Conference, 1980, pp.38-41.
12. H. Steinbigler, “Combined application of finite element method and charge simulation method for the
computation of electric fields”, 3rd ISH Symp., Milan, 1979, paper ll. ll.
13. H. Singer, H. Steinbigler and P. Weiss, "A charge simulation method for the calculation of high voltage fields",
IEEE Trans., Vol. PAS-93, 1974,pp. 1660-1668.
14. N. H. Malik and A. Al - Arainy, “Charge simulation modeling of three core belted cables”, IEEE Trans.
Electrical Insulation, Vol.20, No.3, 1985, PP. 499 – 503.
15. A.H. Cookson, P.C. Bolin, H.C. Doepken, R. E. W o o t t on, C. M . Co o ke an d J. G. Tru mp , " Recen t Research in
the United States on the Effect of Particle Contamination Reducing the Breakdown Voltage in Compressed Gas
Insulated System", Int. Conf. On Large High Voltage System; Paris, 1976
16. H. C. Doepken Jr., "Compressed gas insulation in large coaxial systems", IEEE Trans. Power App. Syst., Vol. 88,
pp. 364-369, 1969
AUTHOR’S DETAILS
A. Giriprasad Recieved the B.Tech degree in electrical engineering from Velagapudi Ramakrishna Siddhartha
engineering college ,Acharya Nagarjuna
www.tjprc.org
university,Vijayawada, AP, India in 2000 and the M.Tech power systems from
editor@tjprc.org
A. Giriprasad, J. Amarnath & Poonam Upadhyay
54
JNT University Hyderabad, AP,India in 2005. He is life member of ISTE. He has 14 years of teaching experience and
presently working as Associate Professor and HOD in EEE Department, St Peter‟s Engineering College, Hyderabad.
His areas of interest are Gas Insulated Substations and High Voltage Engineering. He has presented and published four
research papers in national and international conferences and journals .
J. Amarnath obtained the B.E degree in electrical engineering from Osmania University, Hyderabad, A.P.,
India in 1982 and the M.E. degree in power systems from Andhra University, Visakhapatnam in
1984.
He worked in Tata Electric Company, Bombay during 1985-1986. In 1987 he was a Lecturer in Andhra University for a
period of 2 years and then he joined Nagarjuna University for a period of 4 years as Lecturer. In 1992 he joined
JNTU College of Engineering, Kukatpally, Hyderabad. Presently he is professor of Electrical and Electronics engineering
department, JNTU, Hyderabad, A.P., He presented more than 120 research papers in national and international
conferences. His research interests includes high voltage engineering, gas insulated substations, industrial drives, power
electronics, power systems, microprocessors and microcontroller applications to power systems and industrial drives .
Poonam
Upadhyay
is
B.E.(Electrical
Engineering)
from
NIT
Raipur
in
1992,
M.Tech
(Integrated Power Systems) from VNIT Nagpur in 1997 and Ph.d in Electrical Engineering from JNTU,
Hyderabad in 2008. She has published 14 papers in various international, national conferences and journals.
She is life member of ISTE. She has 17 years of teaching experience and presently working as professor in department of
Electrical and
Electronics
Engineering
in
VNR Vignana Jyothi Institute of Engineering and Technology,
Hyderabad. She has the research interest in High Voltage Engineering and also in Artificial Neural Network applications in
Electrical Engineering.
Impact Factor (JCC): 5.9638
Index Copernicus Value (ICV): 3.0