X International Symposium on
Lightning Protection
9th-13th November, 2009 – Curitiba, Brazil
EFFECTIVE LAYOUT OF SURGE ARRESTERS ON DISTRIBUTION LINE
Tomoyuki Sato1, Akira Asakawa1, Shigeru Yokoyama1,
Hideki Honda2, Kazuhiro Horikoshi2
1.
Central Research Institute of Electric Power Industry, Japan
2
Tohoku Electric Power Co.,Inc, Japan
E-mail: satot@criepi.denken.or.jp (Tomoyuki Sato)
Abstract - Two- or three-phase ground faults due to
lightning overvoltage, which subsequently result in
two- or three-phase short circuits, lead to heating and
burnout of conductors owing to follow current (fault
current) arcing. Since single-phase ground faults on
Japanese power distribution lines, which adopt an
insulated system, do not lead to such a situation, one
of three surge arresters can potentially be eliminated.
The authors examined the rational and effective
layout of surge arresters of power distribution lines
for the purpose of further cost reductions. The main
resuls are as follows.
(1) When the invasion point of lightning current was
the outer phase conductor, distribution lines with one
surge arrester in each pole are less affected than those
with two surge arresters every two poles.
(2) Surge arresters alternately installed on two phases
and one phase provide better protection effects than
other methods.
1 INTRODUCTION
In order to achieve higher power supply reliability, it is
important to reduce lightning outages. On the other hand,
the cost performance of lightning protection methods
should be considered to meet the economic circumstance.
Many factors, such as the cause of lightning surge, the
topology of power distribution lines and their insulated
level, should be taken into account in order to establish
on efficient lightning protection method for power
distribution lines.
Lightning protection of Japanese power distribution
lines involved the installation of surge arresters and
grounding wire, and the reduction of grounding resistance
value until about 1990. After 1990, lightning protection
was improved by developing and applying surge arresters
to arcing horns using a zincoxide element. Two- or threephase ground faults due to lightning overvoltages, which
subsequently result in two- or three-phase short circuits,
lead to heating and burnout of conductors owing to
follow current (fault current) arcing. Since single-phase
ground faults on Japanese power distribution lines, which
adopt an insulated system, do not lead to such a situation,
one of three surge arresters can potentially be eliminated.
Usually, sparkover first occurs on the outer phase in a
horizontal arrangement, so the middle phase should be the
one that is eliminated [1], [2]. Because this protection
method is effective for cutting cost of the power
distribution system, some Japanese power companies
have already adopted this method.
However, there is little research on a rational and
effective layout of surge arresters for power distribution
lines. The authors examined the rational and effective
layout of surge arresters of power distribution lines for
the purpose of further cost reductions.
2 OUTAGE DUE TO LIGHTNING STRIKES ON
POWER DISTRIBUTION LINES
The number of outages due to lightning strikes on
Japanese power distribution lines is shown in Figure 1.
Although the overall number of outages due to lightning
strikes is decreasing, the damage to high-voltage
conductors has been increasing in recent years.
In Japan, lightning in winter is concentrated in the area
facing the Sea of Japan, and the characteristics of winter
lightning differs greatly from those of the usual summer
lightning. Figure 2 show the ratio of the cumulative
lightning strike frequency in terms of the peak value of
lightning strike current in an electric power company that
supplies electricity to the area facing the Sea of Japan
(Statistics from 1994 to 2007 by Lightning Location
System). As for a lot of lightning in winter, lightning
striking current exceeds 50 kA. The lightning striking
current, which is smaller than 15kA, holds 30% through
the year.
The population density differs for each electric power
company, as does, consequently, the business
environment of each electric power company. Therefore,
it is important to adopt effective lightning protection
575
1200
Conductor
Damage of high-voltage conductor is increasing in recent yeaes.
Pole transformer
1000
Arrester
Air switch
Insulator
affairs
800
600
400
2007
2006
2005
2004
2003
2002
2001
2000
1999
1998
1997
1996
1995
1994
1993
1992
1991
1990
1989
1988
1987
1986
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
0
1973
200
(Quotation from statistical material of FEPC)
Fig. 1. Number of outages due to lightning strikes.
methods in each area [1], [2]. Because the electric power
industry has been restricting investment on power
distribution equipment, more efficient and effective
lightning protection methods are urgently required.
The observation of lightning performance on power
distribution lines in Japan reveals that sparkovers due to
indirect lightning hits rarely occur in Japan [3]. In this
study, the effective layout of surge arresters of power
distribution lines was examined the protection against
direct lightning hits on power distribution lines.
Lightning in summer
50kA or
more
11%
From 25kA
or more to
50kA or less
25%
Less than
15kA
34%
From 15kA
or more to
25kA or less
30%
Lightning in winter
50kA or
more
23%
From 25kA
or more to
50kA or less
24%
Less than
15kA
32%
From 15kA
or more to
25kA or less
21%
3
EXAMINATION METHOD
3.1 Experimental method
A 12MV high-voltage impulse generator was used at
the Shiobara Testing Yard of CRIEPI. Testing facilities
were arranged as shown in Figure 3. The power
distribution line is from pole No.1 to pole No.11. The
power distribution line consists of 60sq conductors, and a
phase conductor consists of three wires. The ends of the
power distribution line were terminated with 380 
resistance to suppress the reflective effect. Many
messenger wires are installed on poles of actual
distribution line. Because messenger wires have the same
effect as overhead ground wires, wires with a diameter of
22sq are installed from pole No.1 to pole No.11. The
grounding resistance of the messenger wires is about 60
at each pole. Four layouts were examined, as shown in
Table 1. The peak value of the lightning current is
examined when sparkover occurs in two phases of the
power distribution line. The test parameters are as follows.
(1) Invasion point of lightning current:
 Top of concrete pole
 Outer phase conductor
(2) Polarity of lightning current: Negative polarity
(3) Peak value of lightning current: 3-18kA
(4) Front time of lightning current: 0.5 and 3.0 s
Moreover, the occurence frequency of lightning strikes
with the peak value of the lightning current, which can
generate sparkover in two phases, was calculated using
formula (1) with the data in Table 2.
Fig. 2. Cumulative frequency of the peak value of lightning
striking current.
f( x) 
576
1
2 
e

x   2
2 2
(1)
No.5
No.6
(42 m)
20 m
(40 m)
(42 m) No.7
IG
(42 m)
No.4
Table 2. Cumulative frequency distribution of lightning
current waveform.
Ref.
50%-value ()
Standard deviation ()
26kA
0.325
[4]
Electrode
(42 m)
Distribution line
(3-phase 3-wire OC60 ㎜ 2）
conductors
Pin type insulator
(LIWN 70kV)
No.8
Messenger wire of communications line
(Fe22 ㎜ 2×1, Ground resistance:60Ω)
(40 m)
No.3
No.9
(40 m)
(40 m)
No.11
No.2
(48 m)
(54 m)
Fig. 4. Surge arrester used in the experiment.
No.10
No.1
Terminal resistance 380 Ω
Grounding resistance 155 Ω
Current lightning elements
Terminal resistance 380 Ω
Grounding resistance 45 Ω
Table 3. Specifications of surge arrester.
Lightning impulse
discharge inception
voltage
Residual voltage
Power-frequency
withstand voltage
Nominal discharge
current（8/20μs）
Fig. 3. Layout of experimental distribution line.
Table 2 shows the 50% value and standard deviation
for the cumulative frequency distribution of the peak
value of lightning strike current according to the
recommendation of CRIEPI [4].
150mm2(Top bind)
83 kV
24kV
22kV
2.5kA
3.2 Surge arrester and pin insulator
3.3 EMTP analysis
As shown in Figure 4 and Table 3, surge arresters
attached to a pin insulator were used. The surge arrester
was set at the bottom of the arc horn of an insulator and
has a metaloxide component. This type of surge arrester
does not require the grounding facility necessary for
conventional surge arresters. The surge arrester for the
middle phase was omitted. The lightning impulse
withstand voltage of a pin insulator is 70kV.
When sparkover in two phases does not occur at lower
than 18kA, which is the limit value of an impulse
generator, analysis using EMTP was performed. The
layout of power distribution lines shown in Figure 3 was
simulated. The length of the power distribution line is the
same as that at Shiobara Testing Yard. The model circuit
is represented by the FD-LINE model (called the J. Marti
line model). The conductor arrangement of the power
Table 1. Layouts of examined surge arresters.
case
Layout of examined surge arrester
case A
No surge arrester
:Surge arrester
No1
:No surge arrester
No2
No3
No4
Outer phase
Middle phase
Inner phase
case B
case C
case D
Surge arresters of one phase
is installed in each pole
Two surge arresters are
installed every two pole.
Surge arresters are installed
alternately on two phases
and one phase.
Outer phase
Middle phase
Inner phase
Outer phase
Middle phase
Inner phase
Outer phase
Middle phase
Inner phase
577
：distrubution line(OC60mm2)
No5
No6
No7
No8
：messenger wire
No9 No10 No11
distribution line used for this analysis is shown in Figure
5. The pin insulator is assumed to discharge at 100kV for
the EMTP analysis. The model of a surge arrester consists
of a zincoxide element with nonlinear characteristics of
voltage and current, as shown in Figure 6. Furthermore,
the EMTP analysis condition is shown in Table 4. The
waveform of lightning strike current is simulated by the
Ramp wave.
The peak value of the lightning current was examined
when sparkover occurred at two phases of the power
distribution line.
4
EXPERIMENTAL AND SIMULATION
RESULTS
The peak values of lightning current that can produce
sparkover at two phases of power distribution lines are
shown in Table 5. Moreover, in order to identify an
effective layout of surge arresters, the relationship
between the peak value of the lightning currents and
wavefront steepness is shown in Figure 7.
A phase conductor
(OC : 60 sq)
0.75 m
Messenger wire
(Steel wire : 22 sq)
0.75 m
0.5 m
10 m
6m
Ground resistance of a
concrete pole: 150 
The main experimental results are as follows.
(1) case A: No surge arrester
Invasion point of lightning current: Top of concrete pole
The peak value of 4 to 5kA produced sparkover in two
phases.
Invasion point of lightning current: Outer phase
conductor
The peak value of the lightning current from about 4 to
8kA produced sparkover in two phases. If lightning hits a
pole without surge arresters, as in case C, the peak value
is the same as this case.
(2) In cases B, C and D, two-phase sparkovers occur
between different poles without surge arresters.
(3) When the invasion point of lightning current is the
outer phase conductor, case B is more effective than case
C. For the perpendicular arrangement of the power
distribution line, a single-phase surge arrester at the
highest phase may be effective, on the basis of the above
results.
(4) As a matter of course, case D with many surge
arresters is the most effective.
(5) The effects of lightning protection are as follows.
Invasion point of lightning current: Top of concrete pole
case A < case B < case C < case D
Invasion point of lightning current: Outer phase
conductor
case A < case B < case C < case D
Moreover, there were many test cases in which of 90%
or higher incidence frequency of the peak value of
lightning current can generate sparkover in two phases.
This is because the time to reach the crest value is
assumed to be 0.5 and 3.0s under severer conditions.
Because the nominal voltage of power distribution lines
in Japan is 6.6kV, the insulation level is designed to be
comparatively low. The peak value of lightning current,
that produces sparkover in two phases of a distribution
line, will be higher for the larger insulation level of
insulators than the lower one.
Fig. 5. Conductor arrangement of the power distribution line.
Table 4. Parameters of equipment.
Item
Setting value
25000
High-vltage conductor
OC60sq
20000
Messenger wire of communication line
Fe22sq
15000
Surge impedance of concrete pole
250 
10000
Propagation speed
300 m/μs
Grounding resistance of a concrete pole
150 
Surge arresters
V2.5 kA =33 kV
Gap: 83kV
Sparkover voltage of pin insulator
100kV
Voltage(V)
30000
5000
0
0
5000
10000
15000
current(A)
20000
25000
Fig. 6. VI characteristic of ZnO.
578
Table 5. Peak value lightning current when sparkover occurs at two phases of distribution line in each test case.
Layout of examined
surge arrester
Case
A
No surge arrester
B
Surge arrester of one
phase is installed in
each pole.
C
Two surge arresters
are installed every two
pole.
D
Surge arresters are
installed alternately on
two phases and one
phase.
Invasion point of
lightning current
Time to crest
value[s]
Top of concrete
pole
Outer phase
conductor
Top of concrete
pole
Outer phase
conductor
Top of concrete
pole
Outer phase
conductor
Top of concrete
pole
Outer phase
conductor
0.5
3.0
0.5
3.0
0.5
3.0
0.5
3.0
0.5
3.0
0.5
3.0
0.5
3.0
0.5
3.0
Invasion point of lightning current: Top of the concrete pole
peak value of the lightning
current when sparkover
occurs in two phases[kA]
4.13
5.52
4.96
8.24
6.00
8.16
7.36
13.28
6.48
11.20
6.16
10.08
8.96
19.3
13.44
26.1
5
Incidence
frequency
[%]
99.3
98.1
98.7
93.8
97.5
93.9
95.4
81.5
96.8
87.0
97.3
89.7
92.3
65.5
81.1
49.8
CONCLUSION
Peak value of lightning current (kA)
20
caseD
15
caseC
10
caseB
caseA
5
:Analysis value
0
0
5
10
15
20
Wavefront steepness （kA/μs）
Invasion point of lightning current: Outer phase conductor
Peak value of lightning current (kA)
30
25
caseD
20
15
caseC
In this study, the effective layout of surge arresters on
power distribution lines was clarified by experiment and
by an analysis using EMTP.
The results are summarized as follows.
(1) When the invasion point of lightning current is the
outer phase conductor, power distribution lines with one
surge arrester for each pole is effective than those with
surge arresters installed every two poles.
(2) Surge arresters alternately installed on two phases and
one phase exhibit better protection effects than other
methods
The above results may be applicable to areas where
lightning is not so frequent in order to establish a better
cost performance. However, it is necessary to consider
the lightning stroke frequency and the importance of the
supply area. An effective layout of surge arresters should
be decided, taking the simulation results obtained using
the EMTP into account.
caseB
6
REFERENCES
10
caseA
5
:Analysis value
0
0
5
10
15
20
25
30
Wavefront steepness　（kA/μs）
Fig. 7 . Relationship between the peak value of lightning
current and wavefront steepness.
[1] S.Yokoyama, “Lightning protection methods on power
Distribution line”, OHM, Japan, 2005.
[2] Subcommittee for Power Distribution Systems, Lightning
Protection Design Committee, “Guide of Lightning
Protection Design for Power Distribution Lines”, Central
Research Institute of Electric Power Industry, Japan, Tech.
Rep. T69, Feb, 2002.
[3] T.Hirai, T.Takami, S.Okabe, “Analysis on Occurrence of
Following Current Caused by Lightning Strokes on Real
Distribution Lines,” 2002 Annual Meeting Record IEE
Japan, No.7-024, pp35,2002.(in Japanese)
579
[4] Subcommittee for Transmission Lines, Lightning Protection
Design Committee, “Guide to Lightning Protection Design
for Transmission Lines”, Central Research Institute of
Electric Power Industry, Japan, Tech. Rep. T72, Feb, 2003.
[5] S.Yokoyama, A.Asakawa, “Experimental Study of Response
of Power Distribution Lines to Direct Lightning Hits”, IEEE
Trans. on power Delivery, Vol.14, No.4, pp.2242-2248,1989.
[6] Y.Asaoka, A.Asakawa, S.Yokoyama, K.Nakada,
H.Sugimoto, “Experimental Study of Occurrence Condition
of Short Circuit and Earth Fault between Different Poles by
Omitting One Phase’s Current Limiting Arcing Horn on
Single-Phase Distribution Lines”, The Papers of Joint
Technical Meeting on Electrical Discharge, Switching and
Protecting Engineering and High Voltage, IEE Japan. ED03-195, SP-03-117, HV-03-110, 2003.(in Japanese)
[7] H.Taniguchi, A.Asakawa, S.Yokoyama, K.Nakada,
K.Ohnishi, T.Motobayashi, “A study on lightning
performance of power distribution line without surge
arresters on one phase”, T.IEE Japan, Vol.114-B, No.11,
pp.1150-1159, 1994.(in Japanese)
[8]
S.Yokoyama,
K.Miyake,
T.Shindo,
A.Asakawa,
H.Motoyama, A.Wada, T.Wakai, T.Sakai, “Caraccteristics
of Lightning in Winter and Manner of Outages on Power
Lines Due to It”, Proc. Of 10th ISH, Vol.5, pp.205-208,1997.
[9] S.Yokoyama, “Distribution Surge Arrester Behavior due to
Lightning In duced Voltage”, IEEE Trans. Power Delivery,
Vol.PWRD-1, No.1, pp.171-178, 1986.
[10] A.Asakawa, T.Yokota, Y.Hashimoto, K.Nakada, “In
fluence of Lightning Current Wave Front on Direct
Lightning Hits to Power Distribution Lines”, CRIEPI Rep.,
No.T94064, 1995. (in Japanese)
[11] K.Nakada, T.Yokota, S.Yokoyama, A.Asakawa,
M.Nakamura,
H.Taniguti,
A.Hashimoto,
“Energy
Absorption of Surge Arresters on Power Distribution Lines
due to Direct Lightning Strokes –Effects of an Overhead
Ground Wire and Installation Position of Surge Arresters-“,
IEEE PES Winter Meeting, PE-384-PWRD-0-01-1997,
1997.
580