High Temperature –Low Sag (HTLS) Conductors...tension in theconductorspan. • Cores may be of...
Transcript of High Temperature –Low Sag (HTLS) Conductors...tension in theconductorspan. • Cores may be of...
1
Page 1
وزارة الكهرباء والطاقة المتجددة
Egypt
High Temperature – Low Sag
(HTLS) Conductors
Professor Ahdab Elmorshedy
President of the Egyptian CIGRE
National Committee
Ministry of Electricity and
Renewable Energy
1Professor Ahdab Elmorshedy
وزارة الكهرباء والطاقة المتجددة
Egypt
1. Introduction
2. Methods of Increasing Lines Capacity
3. Transmission Conductors
• Conventional Types of Conductors
• High Temperature Low Sag (HTLS) Conductors
4. Types of HTLS Conductors
5. Advantages of HTLS Conductors
6. Gap and Invar Conductors
• Design Concept of Gap and Invar Conductors
• Supply Record of JPS HTLS Conductors
• Gap type conductor: Maintenance
7. Disadvantages of HTLS Conductors2
2
Page 2
وزارة الكهرباء والطاقة المتجددة
Egypt
1. Introduction
• There is a growing need to increase the power
handling capacity of existing power
transmission assets.
• There is fierce opposition to the construction
of new lines and the ability of obtaining right
of ways is more and more difficult.
3Professor Ahdab Elmorshedy
وزارة الكهرباء والطاقة المتجددة
Egypt
• As a result: increasing the thermal rating of
existing overhead transmission lines is seen as
a valid alternative to the construction of new
lines.
• One of the prime physical limits on overhead
transmission lines is conductor sag.
4Professor Ahdab Elmorshedy
3
Page 3
وزارة الكهرباء والطاقة المتجددة
Egypt
• Sag is limited to meet the clearance requirements
� of the line,
� between the line and ground, and
� between conductors, under maximum load
conditions.
• If the sag is too large, it may cause
� a short circuit between the line and objects below it or
� a short circuit between lines in extremely windy
conditions.
5Professor Ahdab Elmorshedy
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 6
4
Page 4
وزارة الكهرباء والطاقة المتجددة
Egypt
• Conductor sag in a transmission line span is
affected by both temperature and ice, which
increases the weight on the span.
• In Egypt, conductor temperature is the most
influential factor on sag.
• This limits the amount of current which is
allowed to flow in the transmission line.
7Professor Ahdab Elmorshedy
وزارة الكهرباء والطاقة المتجددة
Egypt
Conductor temperature
The temperature of a conductor depends on a
number of factors including:
• Current flowing in the conductor
• Ambient temperature
• Solar radiation level
• Wind speed
8Professor Ahdab Elmorshedy
5
Page 5
وزارة الكهرباء والطاقة المتجددة
Egypt
Temperature Effects on Aluminum
Conductors
• Standard overhead conductors are made from hard
drawn aluminum (HDA), which increases the tensile
strength over that of aluminum rod by a factor of
almost three.
• However this limits the temperature, as above 100°C
the HDA starts to anneal and lose its tensile strength.
Anneal: to make metal or glass soft by heating
and then cooling it slowly to free from internal
stress.
9Professor Ahdab Elmorshedy
وزارة الكهرباء والطاقة المتجددة
Egypt
1. Introduction
2. Methods of Increasing Lines Capacity
3. Transmission Conductors
• Conventional Types of Conductors
• High Temperature Low Sag (HTLS) Conductors
4. Types of HTLS Conductors
5. Advantages of HTLS Conductors
6. Gap and Invar Conductors
• Design Concept of Gap and Invar Conductors
• Supply Record of JPS HTLS Conductors
• Gap type conductor: Maintenance
7. Disadvantages of HTLS Conductors10
6
Page 6
وزارة الكهرباء والطاقة المتجددة
Egypt
2. Methods of Increasing Lines Capacity
• Increment of the line voltage
• Increment conductor tension
• Increment of conductor section
• Installation of bundle conductor
- very expensive solutions, cause problems in
towers, necessity of reinforce tower,
foundations, permissions, higher right of ways.
Professor Ahdab Elmorshedy 11
وزارة الكهرباء والطاقة المتجددة
Egypt
1. Introduction
2. Methods of Increasing Lines Capacity
3. Transmission Conductors
• Conventional Types of Conductors
• High Temperature Low Sag (HTLS) Conductors
4. Types of HTLS Conductors
5. Advantages of HTLS Conductors
6. Gap and Invar Conductors
• Design Concept of Gap and Invar Conductors
• Supply Record of JPS HTLS Conductors
• Gap type conductor: Maintenance
7. Disadvantages of HTLS Conductors12
7
Page 7
وزارة الكهرباء والطاقة المتجددة
Egypt
3. Transmission Conductors
Professor Ahdab Elmorshedy 13
وزارة الكهرباء والطاقة المتجددة
Egypt
Conventional Types of Conductors
• There is no unique process by which all transmission
and/or distribution lines are designed.
• The major cost components of line design depend upon
the conductor electrical and mechanical parameters.
• There are four major types of overhead conductors used
for electrical transmission and distribution.
1. AAC - All Aluminum Conductor
2. ACSR - Aluminum Conductor Steel Reinforced
3. AAAC - All Aluminum Alloy Conductor
4. ACAR - Aluminum Conductor Aluminum-Alloy
ReinforcedProfessor Ahdab Elmorshedy 14
8
Page 8
وزارة الكهرباء والطاقة المتجددة
Egypt
1- ACSR conductor (Aluminum conductor steel-
reinforced cable)
ACSR (Aluminum Conductor Steel Reinforced) -
Conventional Conductors With Steel Core
Professor Ahdab Elmorshedy 15
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 16
AAAC formation
2- AAAC Conductors (All Aluminum Alloy Conductor)
9
Page 9
وزارة الكهرباء والطاقة المتجددة
Egypt
Conventional Aluminum Based Conductors
Overheating = Loss of mechanical properties
• ACSR conductors: made of steel core + Al 1350
wires (a non-treated heatable alloy that is hardened by
cold working)
• If working temperature > 90ºC will lose significant
tensile strength (“anneal”) over time
• As the conductor temperature increases, the rate of
annealing increases rapidly
• Galvanized steel core is affected at 170 ºC
• Aluminum Clad steel core is not affected below
300ºCProfessor Ahdab Elmorshedy 17
وزارة الكهرباء والطاقة المتجددة
Egypt
Conventional Conductors
Typical annealing curves for Aluminum wires
Professor Ahdab Elmorshedy 18
Aluminum Cables 1350-H19
10
Page 10
وزارة الكهرباء والطاقة المتجددة
Egypt
High Temperature Low Sag (HTLS)
Conductors
• HTLS conductors solve the challenges of
higher temperature and higher tensile
strength.
• HTLS uses annealed aluminum or aluminum
alloy conductors and a high tensile strength
core which carries both the weight and the
tension in the conductor span.
• Cores may be of metallic or composite
material construction.Professor Ahdab Elmorshedy 19
وزارة الكهرباء والطاقة المتجددة
Egypt
• HTLS conductors make use of an inner core
with higher tensile strength than the aluminum
conductors.
• This allows higher tension to be applied to the
conductor which allows reduced sag.
• Several materials have been used.
Professor Ahdab Elmorshedy 20
11
Page 11
وزارة الكهرباء والطاقة المتجددة
Egypt
Why HTLS Conductors
• Supporting the seasonal or occasional demand peaks
as well as emergency overloads required by the grid
operation during line life.
• Continuous operation at higher temperatures thus,
increasing the electrical load.
• Do not modify the structures (towers and
foundations)
• Maintain adequate electrical clearances (maximum
sags)
• Increase the current capacity 1.6-2.0 times of ACSR.
Professor Ahdab Elmorshedy 21
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 22
Power Line Reconductoring Project Video
The Pacific Gas and Electric Company (PG&E)
crew working on a power line.
12
Page 12
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 23
وزارة الكهرباء والطاقة المتجددة
Egypt Conventional versus HTLS Conductors
Material characteristics:
•Thermal coefficient of expansion of Invar (alloy of steel and
nickel) is 1/3 of steel
•Annealing temperatures of aluminum 930ᵒF
Professor Ahdab Elmorshedy 24
Conventional HTLS
Inner Core Steel Steel alloy
Composite (carbon
or aluminum)
Outer Strands Aluminum Circular Annealed
Aluminum
Aluminum Alloy
Trapezoidal
13
Page 13
وزارة الكهرباء والطاقة المتجددة
Egypt
1. Introduction
2. Methods of Increasing Lines Capacity
3. Transmission Conductors
• Conventional Types of Conductors
• High Temperature Low Sag (HTLS) Conductors
4. Types of HTLS Conductors
5. Advantages of HTLS Conductors
6. Gap and Invar Conductors
• Design Concept of Gap and Invar Conductors
• Supply Record of JPS HTLS Conductors
• Gap type conductor: Maintenance
7. Disadvantages of HTLS Conductors25
وزارة الكهرباء والطاقة المتجددة
Egypt
4. Types of HTLS Conductors
1-Aluminium conductor steel support (ACSS),
Southwire, USA
2-Aluminum conductor composite reinforced (ACCR),
3M, USA
3-Aluminum conductor composite core (ACCC), CTC,
USA
4-Gap type thermal resistant aluminum alloy conductor
steel reinforced, J-Power, JAPAN- LS Cable, KOREA
5- Invar Core Conductor, LS Cable, KOREA
Professor Ahdab Elmorshedy 26
14
Page 14
وزارة الكهرباء والطاقة المتجددة
Egypt
Knee Point Temperature (KPT)
• KPT is a temperature at which Aluminum layers do
not bare any tension due to its thermal expansion in
ACSR conductor.
• Above KPT the Tension is on the Steel core only.
• Knee point temperature depends on many factors like
span length and mechanical tension.
Professor Ahdab Elmorshedy 27
وزارة الكهرباء والطاقة المتجددة
Egypt
Knee Point Temperature
• HTLS conductors have different physical behavior
when working below or above the knee point
temperature.
• The conductor’s core thermal expansion coefficient is
a key factor in the conductor performance, when it is
working above KPT.
• There are some technologies that reduces the knee
point temperatures improving conductor
performance.
Professor Ahdab Elmorshedy 28
15
Page 15
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 29
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 30
16
Page 16
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 31
وزارة الكهرباء والطاقة المتجددة
Egypt
1-Aluminium conductor steel support (ACSS)
• The outer conductor is annealed aluminum
with an inner core of high tensile steel.
• The HTS core carries the tension in the cable.
Professor Ahdab Elmorshedy 32
Aluminum conductor steel
support (ACSS)
17
Page 17
وزارة الكهرباء والطاقة المتجددة
Egypt
ACSS/TW Conductor
Professor Ahdab Elmorshedy 33
CenterPoint Energy Houston, Texas
وزارة الكهرباء والطاقة المتجددة
Egypt
2-Aluminum conductor composite reinforced
(ACCR)
Professor Ahdab Elmorshedy 34
Aluminum conductor composite reinforced (ACCR)
18
Page 18
وزارة الكهرباء والطاقة المتجددة
Egypt
• The core is stranded from wires of high purity
aluminum reinforced with alumina fiber.
• The outer, current carrying wires are a
hardened aluminum zirconium alloy.
• The resulting conductor has the same strength
as similar size steel core conductors, but is
much lighter and sags less.
Professor Ahdab Elmorshedy 35
وزارة الكهرباء والطاقة المتجددة
Egypt 3M Metallic Matrix Composite Core
ACCR (Aluminum Conductor Composite Reinforced)
Professor Ahdab Elmorshedy 36
San Diego Gas & Electric- California
19
Page 19
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 37
3M™ ACCR - Protecting Grid Integrity-Video
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 38
20
Page 20
وزارة الكهرباء والطاقة المتجددة
Egypt
3-Aluminum conductor composite core
(ACCC)
• The conductor consists of an outer core of
trapezoidal conductors with an inner carbon
fiber/fiber glass composite core.
Professor Ahdab Elmorshedy 39
Aluminum conductor composite core (ACCC)
وزارة الكهرباء والطاقة المتجددة
Egypt
• It is able to carry approximately twice as much
current as a conventional aluminum-conductor steel-
reinforced cable (ACSR) cable of the same size and
weight.
• It is popular for retrofitting an existing electric power
transmission line without needing to change the
existing towers and insulators.
Professor Ahdab Elmorshedy 40
21
Page 21
وزارة الكهرباء والطاقة المتجددة
Egypt
CTC Carbon Fiber Composite Core Conductor
Aluminum conductor composite core (ACCC)
Installed at APS (Arizona Public Service)
Professor Ahdab Elmorshedy 41
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 42
Sag Comparison Test Data: temperature vs. sag of various
conductor types on a 215' test span.
22
Page 22
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 43
Sag comparison at 180°C
وزارة الكهرباء والطاقة المتجددة
Egypt
• In 2010, demand for electricity in southern Texas
reached an all-time high during a peak winter season.
• Power provided to this region was supplied by two
345 kV lines 193 km long.
• In 2013 American Electric Power (AEP) began
upgrading the existing lines.
• Using a live-line technique, they replaced over 2300
km of double-bundled aluminum conductor steel-
reinforced cable (ACSR) with double-bundled
aluminum conductor composite core (ACCC) lines.
Professor Ahdab Elmorshedy 44
23
Page 23
وزارة الكهرباء والطاقة المتجددة
Egypt
• ACCC replaced the conventional steel wires with a
single composite core strand.
• The composite core’s lighter weight allows it to
incorporate 28% more aluminum using trapezoidal
shaped strands without a weight or diameter penalty.
• The ACCC Conductor hybrid core is not only twice
as strong as steel, it is also 70% lighter.
Professor Ahdab Elmorshedy 45
وزارة الكهرباء والطاقة المتجددة
Egypt
Example of sag differences in the field (UK)
24
Page 24
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 47
Live-line technique Video
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 48
25
Page 25
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 49
Ice loaded tress failed to damage ACCC, Kansas (US),
2007.
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 50
ACCC power plant upgrade
26
Page 26
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 51
Conductor comparison showing ampacity capabilities.
وزارة الكهرباء والطاقة المتجددة
Egypt
• GAP-Type Conductors is composed
of layers of thermal resistant
aluminum alloy wires around a high
strength steel core.
• Grease is filled in the gap to make
the steel core move freely, giving the
conductor its special characteristics.
Professor Ahdab Elmorshedy 52
4-Gap type thermal resistant aluminum alloy
conductor steel reinforced
27
Page 27
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 53
Gap HTLS conductor
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 54
Gap Conductor Installed at HydroOne
( Canadian province of Ontario)
28
Page 28
وزارة الكهرباء والطاقة المتجددة
Egypt
Principal behind small sag
Professor Ahdab Elmorshedy 55
وزارة الكهرباء والطاقة المتجددة
Egypt
Issues with Gap conductor
Difficult to use mid-span connectors
– If Gap breaks then the internal steel core immediately
contracts down the conductor core and so a mid-span
joint cannot be made.
– The only alternative is reconductoring the section
Professor Ahdab Elmorshedy 56
29
Page 29
وزارة الكهرباء والطاقة المتجددة
Egypt
Gap relies on the grease staying put
– Oman, Ireland, UK have all experienced Gap losing
its grease
– Sometimes dripping onto people's roofs and cars
– Commonly burning off on the surface and causing
black marks
– The steel is then not protected.
Professor Ahdab Elmorshedy 57
وزارة الكهرباء والطاقة المتجددة
Egypt
• Gap knee point is at erection temperature, so if
sections are erected at different temperatures then
their sag/temperature behavior will be different in the
different sections and this can put stresses on tension
towers.
• Because the aluminum is not connected with the steel
core, the whole conductor can be twisted easily by
hand
Professor Ahdab Elmorshedy 58
30
Page 30
وزارة الكهرباء والطاقة المتجددة
Egypt
• Wet snow can twist the conductor and hence Gap
accretes higher snow loads than, for example, CCC
(CopperClad Composite Conductors).
• It is very slow to erect as the steel core has to be
stripped bare and pre-tensioned for 12 hours.
Professor Ahdab Elmorshedy 59
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 60
LS Cable and System Gap conductor
Video
31
Page 31
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 61
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 62
5- Invar Core Conductors (TACIR, KTACIR,
ZTACIR)
Invar Conductor Installed at
HydroOne ( Canadian province
of Ontario)
32
Page 32
وزارة الكهرباء والطاقة المتجددة
Egypt
Invar conductors use a special steel alloy: Iron–
nickel (Fe-Ni) which main characteristic is the
very low thermal expansion coefficient.
Invar is covered by a thin layer of aluminum
extruded on it which prevent the corrosion and
the wire is identified by the acronym ACI
(Aluminum Clad Invar).
Professor Ahdab Elmorshedy 63
وزارة الكهرباء والطاقة المتجددة
Egypt
33
Page 33
وزارة الكهرباء والطاقة المتجددة
Egypt
1. Introduction
2. Methods of Increasing Lines Capacity
3. Transmission Conductors
• Conventional Types of Conductors
• High Temperature Low Sag (HTLS) Conductors
4. Types of HTLS Conductors
5. Advantages of HTLS Conductors
6. Gap and Invar Conductors
• Design Concept of Gap and Invar Conductors
• Supply Record of JPS HTLS Conductors
• Gap type conductor: Maintenance
7. Disadvantages of HTLS Conductors65
وزارة الكهرباء والطاقة المتجددة
Egypt
5. Advantages of HTLS Conductors
1-Higher Current Carrying Capacity
• HTLS conductors can be operated at elevated
temperatures around 150°C-250°C.
• The amount of current rating of these conductors is
high compared to the conventional conductors.
• Based on the manufacturers’ information, GTACSR
conductors are able to handle 1.6 times the same size
ACSR while GZTACSR can handle 2.0 times the
CCC of similar size ACSR conductors
Professor Ahdab Elmorshedy 66
34
Page 34
وزارة الكهرباء والطاقة المتجددة
Egypt
2- ROW saving
• HTLS conductors can be used to transfer bulk power
from one stations to other, so it has the potential to
reduce number of transmission lines being
constructed.
• Conventional conductors are restricted to low
capacities, so a requirement of multiple transmission
lines is needed and hence ROW requirements will be
large.
• HTLS becomes handy in such situations where they
can eliminate the requirement of multiple lines by a
single tower line.Professor Ahdab Elmorshedy 67
وزارة الكهرباء والطاقة المتجددة
Egypt
3- Thermal Uprating of Existing Lines
• One of the main advantages of HTLS conductors is to
use them as a medium for thermal uprating of
existing transmission lines.
• With the increasing demand, older transmission lines
are unable to supply the required power demand and
construction of new overhead lines became a
challenge given the unavailability of ROW.
• Use of higher cross section line in the existing towers
is not an option as the existing towers are not
designed for additional forces.
Professor Ahdab Elmorshedy 68
35
Page 35
وزارة الكهرباء والطاقة المتجددة
Egypt
• Even if conductors with higher cross section is
used, the thermal sag of conductors will violate
the required ground clearances.
• The best option is to use a suitable HTLS
conductor with similar mechanical properties
where:
• the existing towers can be used without
violating tower safety requirements as well as
minimum ground clearances.
Professor Ahdab Elmorshedy 69
وزارة الكهرباء والطاقة المتجددة
Egypt
4- Energy Efficiency
• Using HTLS conductors achieves energy efficiency
during power transmission.
• Conductivity of the conductors can be improved by
the proper composition of elements and proper heat
treatment methods.
• Energy loss (I2R) during transmission can be reduced
by the use of HTLS conductors.
• This will in turn reduce the amount of power
generation requirements to be met and will save fuel
and CO2.
Professor Ahdab Elmorshedy 70
36
Page 36
وزارة الكهرباء والطاقة المتجددة
Egypt
5- Long Span Crossing
• HTLS conductors can be used for longer spans
crossings.
• This remained a great challenge with ACSR
conductors due to its higher thermal expansion
coefficient.
• At the same time, UTS (Ultimate Tensile Strength)
of conventional conductors is low compared to the
HTLS.
Professor Ahdab Elmorshedy 71
وزارة الكهرباء والطاقة المتجددة
Egypt
• With conventional conductors, taller towers are
required to obtain the ground clearance.
• This also results in the need of additional steel as well
as larger foundations.
• Conventional conductors cannot be tensioned to
higher values as there is a risk of being subjected to
fatigue failure due to wind vibration.
• With lower expansion values and higher UTS values,
HTLS conductors have become a good solution for
long span crossing.
Professor Ahdab Elmorshedy 72
37
Page 37
وزارة الكهرباء والطاقة المتجددة
Egypt
1. Introduction
2. Methods of Increasing Lines Capacity
3. Transmission Conductors
• Conventional Types of Conductors
• High Temperature Low Sag (HTLS) Conductors
4. Types of HTLS Conductors
5. Advantages of HTLS Conductors
6. Gap and Invar Conductors
• Design Concept of Gap and Invar Conductors
• Supply Record of JPS HTLS Conductors
• Gap type conductor: Maintenance
7. Disadvantages of HTLS Conductors73
وزارة الكهرباء والطاقة المتجددة
Egypt
6. Gap and Invar Conductors
Design Concept of Gap and Invar Conductors
• Gap: Shift the Knee Point Temperature (KPT)
to lower side
• Invar: very small thermal expansion at
temperatures above KPT
Professor Ahdab Elmorshedy 74
38
Page 38
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 75
وزارة الكهرباء والطاقة المتجددة
Egypt
Design Concept
• Gap: Shift the Knee Point Temperature (KPT)
to lower side
• Invar: very small thermal expansion at
temperatures above KPT
Professor Ahdab Elmorshedy 76
39
Page 39
وزارة الكهرباء والطاقة المتجددة
Egypt
Gap conductors need Special Tensioning Method
(only Tension Tow.)
Professor Ahdab Elmorshedy 77
وزارة الكهرباء والطاقة المتجددة
Egypt
Gap type conductor: Maintenance
• Repair Sleeve: same as ACSR:
in case of damage less than 10% of AL wires
• Mid Span joint: same as ACSR:
in case of damage more than 11% of AL wires
• Tension load at repaired portion shall have
more than 95% tension load of original
conductor
Professor Ahdab Elmorshedy 78
40
Page 40
وزارة الكهرباء والطاقة المتجددة
Egypt Design Example: Sag-Tension and Ampacity study
Required current capacity: 1250A
GTACSR 448SQ at 115 deg C: 1250A, (Sag 20.36m)
ACSR 435/55SQ at 60 deg C: 643A, (Sag 19.83m)
Professor Ahdab Elmorshedy 79
وزارة الكهرباء والطاقة المتجددة
Egypt
1. Introduction
2. Methods of Increasing Lines Capacity
3. Transmission Conductors
• Conventional Types of Conductors
• High Temperature Low Sag (HTLS) Conductors
4. Types of HTLS Conductors
5. Advantages of HTLS Conductors
6. Gap and Invar Conductors
• Design Concept of Gap and Invar Conductors
• Supply Record of JPS HTLS Conductors
• Gap type conductor: Maintenance
7. Disadvantages of HTLS Conductors80
41
Page 41
وزارة الكهرباء والطاقة المتجددة
Egypt
1- Low Service Experience
• ACSR conductors have more than hundred years
of service experience.
• ACSR conductors are being used all over the
world by thousands of contractors and utilities.
• HTLS conductors came to the world of
transmission line construction at a later stage
where no utility or contractor has that much
service experience regarding its use.
• In case of ACCC conductors, it was first
developed in 2005 and commercialized in 2006.
Professor Ahdab Elmorshedy 81
وزارة الكهرباء والطاقة المتجددة
Egypt
• Presently over 100 utilities in more than 30 countries
are using ACCC over 24,000km span.
• GTACSR conductor first immerge in nineteen
seventies in Japan.
• Use of Gap conductors was merely limited to Japan
until the start of 2000.
• Then it started spreading all over the world and
currently more than 11,000km of supply record is
there.
• All other HTLS conductors such as ACSS, ZTACIR,
ACCC have limited experience regarding the service
life.
Professor Ahdab Elmorshedy 82
42
Page 42
وزارة الكهرباء والطاقة المتجددة
Egypt
2- Difficulties can arise in constructing new lines
with HTLS conductors for a variety of reasons:
• HTLS conductors such as ACCC and ACSS utilize
fully annealed aluminum strands which are more
vulnerable to bird-caging during installation.
• Pulling annealed aluminum HTLS conductors under
tension can be difficult unless the core is part of the
tension grip.
Professor Ahdab Elmorshedy 83
وزارة الكهرباء والطاقة المتجددة
Egypt
Professor Ahdab Elmorshedy 84
Bird-caging of Annealed Aluminum Conductor after
Compressing Dead-end
43
Page 43
وزارة الكهرباء والطاقة المتجددة
Egypt
• With bundled conductors, the use of HTLS sub-
conductors can cause unequal thermal elongation at
everyday temperatures since the knee-point
temperature of the sub-conductors may not be equal.
• Use of composite cores can result in installation
damage since these materials are very sensitive to
shear stress.
• Connectors and dead-ends are unique to each type of
HTLS conductor.
• This presents a potential problem of standardization
and emergency repairs.
Professor Ahdab Elmorshedy 85
وزارة الكهرباء والطاقة المتجددة
Egypt
3- Special Stringing Requirements and Spares
• One of the main disadvantages of some of the HTLS
conductors is the requirement of specialized stringing
methods.
• As an example, ACCC and Gap conductors require
special trained staff on stringing.
• Stringing procedure is different from conventional
methods used with ACSR.
Professor Ahdab Elmorshedy 86
44
Page 44
وزارة الكهرباء والطاقة المتجددة
Egypt
• Especially the dead ends used with ACCC and Gap
conductors shall be compression type to tackle
thermal expansion of Aluminum layer at elevated
temperatures.
• They require special mid span joints unlike in the
case of ACSR.
• They must be handled very carefully during stringing
and cannot be subjected to rough and rigid handling.
Professor Ahdab Elmorshedy 87
وزارة الكهرباء والطاقة المتجددة
Egypt
Unusual Properties Requires Special
Handling
Professor Ahdab Elmorshedy 88
45
Page 45
وزارة الكهرباء والطاقة المتجددة
Egypt
4- High Price of HTLS
• Unit cost of HTLS conductors are considerably
higher compared to the cost of ACSR and AAAC, 2-3
times.
• Most of the utilities in the world have very strict
investment plans on their power systems and
additional cost bearing will cause a great challenge.
Professor Ahdab Elmorshedy 89
وزارة الكهرباء والطاقة المتجددة
Egypt
• Therefore still in case of a new line construction, use
of HTLS will cost additional amount other than the
saving of ROW.
• However in situations where existing line uprating,
HTLS has the ability to cut down the cost of new
transmission line only by restring conductors.
Professor Ahdab Elmorshedy 90
46
Page 46
وزارة الكهرباء والطاقة المتجددة
Egypt
5- Reconductoring with HTLS Limitations
• As power flow increases, the voltage at the
receiving end of the line decreases, power
flow is limited to that which yields a 5% drop
• The flow through particular circuit is limited
in order to avoid overheating a power
transformer or underground cable in series
with OHL, reconductoring with HTLS will not
help.
وزارة الكهرباء والطاقة المتجددة
Egypt
• Replacing existing power conductor while
preserving the original structure, typically
leaves electric and magnetic fields unchanged
as the physical spacing and their geometric
arrangement remain unchanged.
47
Page 47
وزارة الكهرباء والطاقة المتجددة
Egypt
Giza Systems Awarded INVAR Thermal
Conductor Project
• The Egyptian Electricity Transmission Company
(EETC) awarded Giza Systems the project for Cairo
500/ Sadat 220 kV OHTL – Thermal Conductor –
INVAR, March 2015.
• Giza Systems successfully executed Sadat-Cairo 500
INVAR project in significant low outage time, 58 kM.
• Installation of 30 kM Thermal conductor “GAP” for
Wadi Houf / El Tebbin 220 kV.
Professor Ahdab Elmorshedy 93
وزارة الكهرباء والطاقة المتجددة
Egypt
94Professor Ahdab Elmorshedy