Energy Division
Bowthorpe EMP
Transmission Line Arrester
TLA Transmission Line Surge Arrester
Introduction
Numerous technical publications have stated that lightning is responsible for approximately 65% of all
of the non-scheduled outages occurring on transmission lines, thus creating many issues for power
supply utilities.
Power supply utilities themselves have verified the load losses due to voltage sags on their systems
from transitory outages caused by lightning activity and in some regions they have found serious
permanent damage caused to the system itself due to these transitory disturbances
occurring on important lines.
The effect of these transitory disturbances on transmission lines can also be more critical in areas with
high ground resistivity when associated with high lightning activity.
Although it is a fact that most of the non-scheduled outages are transitory in nature, with a fault time
shorter than 1 minute, in many cases this is still deemed, by power supply utilities and their customers,
to be unacceptable. This loss of supply is critical for all modern industries now
so reliant on sophisticated electronic equipment and especially production processes sensitive to
momentary disturbances on the system.
In order to reduce the number of non-scheduled outages in electrical systems, power companies and
industrial consumers have been studying and promoting improvements to transmission lines thereby
increasing their reliability.
There are different methods to improve transmission lines performance due to lightning:
a) Increase the dry arcing distance from the insulators strings.
b) Install shield wires on lines without shield wires.
c) Improve the shield wire performance.
d) Improve the grounding system performance of surges by improving the tower footing
resistance.
e) Installation of transmission line arresters to counteract the effects of lightning or switching
activity
In most cases line arresters (TLA), electrically connected in parallel with the insulator string, have been
considered as the most effective method currently applied to improve transmission line performance
especially when associated with improvements to the grounding system and usually presents the best
benefit versus cost relationship in reducing flashovers of the insulator string due to excessive voltages.
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TLA Transmission Line Surge Arrester
TLA
• Transmission Line Surge Arresters up to 230 kV Suspension Clamp
Standard
• IEC 60099-4 for ZnO Surge Arresters.
• Vibration Test - CEMIG.
Key Features
• HV arrester suspended from a transmission line
Grading Ring for
giving enhanced transmission line performance. voltages above
150 kV
• Increasing system line voltage on standard
insulated transmission lines.
Silicone Rubber
Utility Insulation
• Utilities are required by demand to increase
availability and reliability of transmission
systems. Therefore eliminating operational high
cost outages and mandoratory penalties is high
on the agenda.
Benefits of TLA Installations
• Minimising circuit breaker operation with
Disconnect Device
possible system outage resulting from back
flashover on the transmission line.
Earth Cable with
StrainRelief
• Switching overvoltages are absorbed over the
length of the line reducing the severity of surge
at the substation.
• Transmission systems can be operated even
where sub-soil gives poor tower footing
resistance.
• Eliminating interrupted supply for power supply
for sensitive industrial processes.
• Installing Transmission Line Arresters on a
standard 3 phase voltage system along the line,
at calculated intervals, allows for optimun
performance of the TLA, to give an increased
system line voltage. Therefore eliminating the
need to increase the standard insulation level
required on conventional system upgrade.
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TLA Transmission Line Surge Arrester
Electrical Performance
Specification: IEC60099-4
Classification: 10kA
Voltage Rating: 15 to 252
High Current Performance: 100kA
Line Discharge Class: 2
Minimum Energy Capability:
4.5 kJ/kV at Ur according to IEC60099-4
(Clause 8.4.2 table 5 and 8.5.5)
TLA1 15 - 45 kV
TLA2 48 - 96 kV
TLA3 108 - 144 kV
TLA4 150 - 192 kV
• Disconnect Device tested in accordance
with IEC 60099-4 Class2.
• Insulation Material: Silicone
Rubber
TLA3-120 - 138 kV System, Brazil
• Vibration Tested Report No.
BOE002000
TLA4
TLA Dimensions
300 nom
TLA3
TLA2
A
TLA1
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TLA Transmission Line Surge Arrester
-Electrical performance
Product Code Rating Max Temporay Max residual voltage kV crest with current wave Steep
voltage cont. over - current
kV operating voltage Switching surge Lightning current residual
voltage capability 30/60 µS 8/20 µS voltage *
(COV) kV for 1 sec
(TOV) kV 125A 250A 500A 1000A 2000A 5kA 10kA 20kA 40kA 10kA 20kA
kV crest kV crest kV crest kV crest kV crest kV crest kV crest kV crest kV crest kV crest kV crest
TLA1B15L1E1M0 15 12.0 17.7 29.3 30.1 31.1 32.4 33.9 37.0 39.7 43.8 49.8 42.6 47.1
TLA1B18L1E1M0 18 14.4 21.2 36.6 37.6 38.9 40.5 42.4 46.2 49.7 54.7 62.3 53.3 58.9
TLA1B21L1E1M0 21 16.8 24.8 41.5 42.7 44.1 45.9 48.1 52.4 56.3 62.0 70.6 60.4 66.8
TLA1B24L1E1M0 24 19.2 28.3 48.8 50.2 51.9 54.0 56.6 61.6 66.2 73.0 83.0 71.1 78.5
TLA1B27L1E1M0 27 21.6 31.9 53.7 55.2 57.1 59.3 62.2 67.8 72.8 80.3 91.3 78.2 86.4
TLA1C30L1E1M0 30 24.0 35.4 58.6 60.2 62.3 64.7 67.9 73.9 79.4 87.6 99.6 85.3 94.3
TLA1C36L1E1M0 36 28.8 42.5 70.8 72.8 75.2 78.2 82.0 89.3 96.0 106 120 103 114
TLA1C39L1E1M0 39 31.2 46.0 78.2 80.3 83.0 86.3 90.5 98.6 106 117 133 114 126
TLA1C42L1E1M0 42 33.6 49.6 83.0 85.3 88.2 91.7 96.2 105 113 124 141 121 134
TLA1E45L1E1M0 45 36.0 53.1 87.9 90.3 93.4 97.1 102 111 119 131 149 128 141
TLA2C48L1E1M0 48 38.4 56.6 95.2 97.8 101 105 110 120 129 142 162 139 153
TLA2C60L1E1M0 60 48.0 70.8 117 120 125 129 136 148 159 175 199 171 189
TLA2C72L1E1M0 72 57.6 85.0 142 146 150 156 164 179 192 212 241 206 228
TLA2C75L1E1M0 75 60.0 88.5 147 151 156 162 170 185 199 219 249 213 236
TLA2E84L1E1M0 84 67.2 99.1 166 171 176 183 192 209 225 248 282 242 267
TLA2E96L1E1M0 96 76.8 113 188 193 200 208 218 237 255 281 320 274 302
TLA3C108L1E1M0 108 86.4 127 212 218 226 235 246 268 288 317 361 309 342
TLA3C120L1E1M0 120 96.0 142 234 241 249 259 272 296 318 350 399 341 377
TLA3E138L1E1M0 138 110 163 274 281 291 302 317 345 371 409 465 398 440
TLA3E144L1E1M0 144 115 170 283 291 301 313 328 357 384 423 482 412 456
TLA4C150L1E1M0 150 120 177 293 301 311 324 339 370 397 438 498 426 471
TLAE4168L1E1M0 168 134 198 330 339 350 364 382 416 447 493 560 480 530
TLA4E180L1E1M0 180 144 212 354 364 376 391 410 447 480 529 602 515 569
TLA4E192L1E1M0 192 154 227 376 386 399 415 436 474 510 562 639 547 605
* Residual voltage correction factor as per IEC recommendation 10kV/10kA/m
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TLA Transmission Line Surge Arrester
Mechanical and Reference Information
Total Overall Drawing Pivot Disconnect Strian Data
creepage height Reference Suspension Drawing Relief Sheet
mm mm Clamp Reference System Reference
(nom) (max) Drawing Drawing
Reference Reference
E1 E2
930 321 BOW-19-001 BOW-19-011 BOW-19-012 BOW-EPP-TLA1B-15
930 321 BOW-19-001 BOW-19-011 BOW-19-012 BOW-EPP-TLA1B-18
930 321 BOW-19-001 BOW-19-011 BOW-19-012 BOW-EPP-TLA1B-21
930 321 BOW-19-001 BOW-19-011 BOW-19-012 BOW-EPP-TLA1B-24
930 321 BOW-19-002 BOW-19-011 BOW-19-012 BOW-EPP-TLA1B-27
1310 476 BOW-19-002 BOW-19-011 BOW-19-012 BOW-EPP-TLA1C-30
1310 476 BOW-19-002 BOW-19-011 BOW-19-012 BOW-EPP-TLA1C-36
1310 476 BOW-19-002 BOW-19-011 BOW-19-012 BOW-EPP-TLA1C-39
2000 476 BOW-19-003 BOW-19-011 BOW-19-012 BOW-EPP-TLA1E-42
2000 476 BOW-19-003 BOW-19-011 BOW-19-012 BOW-EPP-TLA1E-45
2620 952 BOW-19-004 BOW-19-011 BOW-19-013 BOW-EPP-TLA2C-48
2620 952 BOW-19-004 BOW-19-011 BOW-19-013 BOW-EPP-TLA2C-60
2620 952 BOW-19-004 BOW-19-011 BOW-19-013 BOW-EPP-TLA2C-72
2620 952 BOW-19-004 BOW-19-011 BOW-19-013 BOW-EPP-TLA2C-75
4000 952 BOW-19-005 BOW-19-011 BOW-19-013 BOW-EPP-TLA2E-84
4000 952 BOW-19-005 BOW-19-011 BOW-19-013 BOW-EPP-TLA2E-96
3930 1428 BOW-19-006 BOW-19-011 BOW-19-013 BOW-EPP-TLA3C-108
3930 1428 BOW-19-006 BOW-19-011 BOW-19-013 BOW-EPP-TLA3C-120
6000 1428 BOW-19-007 BOW-19-011 BOW-19-013 BOW-EPP-TLA3E-138
6000 1428 BOW-19-007 BOW-19-011 BOW-19-013 BOW-EPP-TLA3E-144
5240 1904 BOW-19-008 BOW-19-011 BOW-19-013 BOW-EPP-TLA4E-150
8000 1904 BOW-19-009 BOW-19-011 BOW-19-013 BOW-EPP-TLA4E-168
8000 1904 BOW-19-009 BOW-19-011 BOW-19-013 BOW-EPP-TLA4E-180
8000 1904 BOW-19-009 BOW-19-011 BOW-19-013 BOW-EPP-TLA4E-192
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TLA Transmission Line Surge Arrester
Electrical performance
Accessories
TLA Pivot Suspension Clamp
Suspension
Clamp Assembly
Copper Shorting
Braid / Cable
Galvanised Aluminium
Steel Clamp Line Clamp
Straps &
Fixings
Galvanised
Steel Line M12
palm Connection
134
For Shorting
M16 x 35 Min. Braid / Cable
Full Thread
TLA Surge Arrester
Clamp Conductor Dimensions in. “U” Bolt Weight
Range Dia. A B C D Torque
L2 9.5 -19 mm 180 80 90 40 45 Nm 1.8 kgs
L3 18 - 30 mm 217 90 110 50 45 Nm 3.0 kgs
L4 30 - 45 mm 267 100 120 64 75 Nm 4.3 kgs
L5 45 - 65 mm 320 120 140 86 75 Nm 6.0 kgs
Earthing Configuration
TLA Disconnect - E1 TLA Strain Relief System - E2
TLA Surge Arrester TLA Surge Arrester
Disconnect Device
Earth Connection
Disconnect Device
Strain Relief
Shackle and Swivel
Joint
Earth Connection
Strain Relief Wire
Connection
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TLA Transmission Line Surge Arrester
Electrical performance
Performance
Improving the reliability of a 69kV transmission line effected by lightning.
Individual Towers Protected with TLA
100.0
80.0
Probability
flashover
60.0
of
40.0
20.0
0.0
26 27 34 35 36 43 52 61 63 73 75 81 83 84 86
Tower Numbers
Actual without TLA 1 TLA per circuit 2 TLA’s per circuit
• Installing one TLA on an individual tower reduces the probability of flashover. If you
take a look at (tower 35) which has an 80% probability of flashover, this can be
reduced to less than 60% with one TLA installed on the bottom phase. If a second
TLA is installed the reduction in probability is minimal.
Typical Transmission Line 69 kV
Adjacent Towers Protected With TLA
1000
80.0
Probability
flashover
60.0
of
40.0
20.0
0.0
26 27 34 35 36 43 52 61 63 73 75 81 83 84 86
Tower Numbers
Actual without TLA 1 TLA per circuit 2 TLA’s per circuit
• Installation of additional TLA’s on adjacent towers reduces the probability of
flashover on (tower 35) to less than 30% and then if you install a further TLA on
(tower 35) again the probability of flashover is reduced to less than 20%.
8 10
TLA Transmission Line Surge Arrester
Electrical
Tower Installations
performance
The number of the TLA installed on the tower
depends basically on the tower geometry and
Tower
configuration as well as the earthing transient
impedance behaviour.
Insulator For towers with a horizontal conductor
confiuration, conductors in a single line across
Line the tower, normal practice is to install a TLA on
both of the two outside phase conductors.
TLA For towers with a vertical conductor
configuration, conductors arranged above each
Lead Earth
other, the resultant transient voltageacross the
Disconne insulators string sets is usually higher at the
ct Device
bottom phase, which presents a lower distance
to the soil and lowest coupling with the shield
wire. Therefore, transmission lines with a vertical
configuration and low tower footing impedance,
only one TLA is necessary to install on the
bottom phase, but for higher impedances it
Tower might be necessary to install two and
sometimes three TLA’s.
Insulator
Line A direct lightning strike to the transmission line
without a shield wire will cause discharge
current i(t) to divide into two current waves
travelling on the both directions down the line
with magnitude of i( t ) / 2 (it is valid when we
TLA
consider the impedance of the discharge
channel as infinite).This current therefore
produces a voltage wave v (t) in both
Lead Earth directions which considering as a first approach
Disconne that the transmission line is without losses and
ct Device
distortions, results in a voltage along the line
can be estimated by:
V ( t ) = Z0 . i ( t ) /2
Tower
For lines with shield wires, the voltages on the
top of the tower will be significantly lower and
Insulator Line
will depend on the lightning striking point, the
tower impedance and mainly of the earthing
transient behaviour.
TLA
Disconne
ct Device
Earth Lead
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