KEC International Ltd.
Stringing Methodologies of High Temperature Low Sag (HTLS) Conductors
1 KEC International Ltd. 04/12/2014
Contents
Case Study – Siliguri – Purnea Re-conductoring project
Project scope, details and importance
Major points during planning and pre-execution
Installation Methodology
Man and Machine used
Special Tools and Hardware requirement
Major challenges faced during execution
Benefits and Advantages
Future prospects
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Silliguri-Purnea Re- conductoring Project – A Case Study
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• Re - conductoring Package for 400KV D/C Silliguri - Purnea Transmission line associated with Eastern Region Strengthening scheme-I
Name
• Power Grid Corporation of India Limited
Client
• Supply and Re - conductoring of 173 Km 400KV Silliguri - Purnea D/C Line
Scope
• Gap conductor
Conductor Used
• 18 Months
Duration
Project scope
Increase Power flow Capacity of Siliguri - Purnea 400kV D/C Transmission Line
to two times of the existing line by re-conductoring
Increase of current carrying capacity of sub conductor from existing 614 Amps
to 1228 Amps
No modifications in structures and foundations
Circuit wise implementation by keeping the other circuit live
Time schedule equivalent to stringing of double circuit twin conductor line
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Case Study – 400kV D/C Siliguri – Purnea Line
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- Line length : 175kms
- Line passes through the
chicken neck area having
serious ROW constraints
- Vast Hydro potential in NER
to be accessed through this
corridor
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Power Through Siliguri – Purnea Twin Circuit ( Normal condition)
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Yr.
2009
Yr. 2011
Yr. 2013
Yr. 2017
Net Power on AC system at Siliguri (MW) 3300 2975 2975 2975
Flow in 400kV D/c(quad)(MW) (55%) 1815 1636 1636 1636
Flow in 400kV D/c (twin)(MW) (45%) 1485 1339 1339 1339
Power/circuit in twin line(MW) 743 669 669 669
Current per conductor(kA) 0.54 0.48 0.48 0.48
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Power through Siliguri – Purnea Twin circuit (contingency condition)
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2009 2011 2013 2017
One quad ckt. out
Pole Out Pole Out Pole Out
Net Power on AC system at Siliguri (MW) 3300 4325 5675 5675
Flow in 400kV Quad Line (MW) 1254 2379 3121 3121
Flow in 400kV Twin Line (MW) 2046 1946 2554 2554
Power/circuit in twin line(MW) 1023 973 1277 1277
Current per conductor(kA) 0.74 0.70 0.92 0.92
Outage of quad D/c
Pole + quad S/c
out
Pole + quad S/c
out
Pole + quad S/c
out
Flow in 400kV Quad Line(MW) (38%) - 1644 2157 2157
Flow in 400kV Twin Line(MW) (62%) 3300 2682 3519 3519
Power/ckt in twin line 1650 1341 1759 1759
Current per conductor(kA) 1.19 0.97 1.27 1.27 04/12/2014
Major Considerations during Planning
Brainstorming based on the detailed survey to be carried out
Limited period shutdown and ROW mitigation has to be planned well in advance
Detailed shut down plan to be prepared based on above
Strategy to address Incomplete or deformed existing Towers to be prepared
Variance in Spans as compared to Actual and approved Tower schedule to be studied
Ensure that T & P shall be in good condition so as to avoid breakdown during stringing
Arrangement of high precision and mechanized equipment to be arranged
Experienced and technically skilled work force to be arranged
Safety tools to be arranged
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Installation Methodology of GAP conductor
• More or less Similar Installation method compared to conventional conductor
• At the moment of installation all the tension is applied on steel core on which a steel dead end clamp is compressed
• Aluminum part is left hanging on steel core as dead weight
• After an overnight settlement period, aluminum sleeves are compressed over the steel & conductor
• Line hardware & Insulator strings similar to the one used for conventional conductor with the exception of compression dead end clamp
• Up to 2 times the ampacity with the same existing tower design
• Above the stringing Temperature, thermal expansion characteristic is same as that of steel core, which allows small sag at higher temperature
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Man and Machine
Sl. No Gang Type No. of Gangs Gang Strength Productivity
1 TSE gangs 3 60 8-10 Km/Gang/Month
2 Manual Stringing Gang 3 35 3-4 Km/Gang/Month
Special T&P requirement
• Compress type Stringing Clamp
• Come along Clamp
• Steel Come along Clamp
• Locking Clamp
• Sagging Platform
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Special Tools & Tackles Required for Gap Conductor Stringing
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Pulling Eye Conical Clamp
Steel Clamp Aluminium Cutter
Platform
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Installation activities of Gap Conductor
Damages and shortages
to be rectified
Scaffolding to protect ground infrastructure
Temporary reinforcement in case of higher
construction loading
De-clipping and Three sheave roller installation
Existing conductor is used for pulling new conductor
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Sagging at Suspension Towers:
For longer sections we have to do sagging activity at suspension Tower with the
help of semi strain assemblies and Sagging Platform
For joining conductor, aluminium strings has to be pressed at sagging platform
which requires skilled labour and advance jointing machines
Precautions to be taken during stringing
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Technical Benefits during Installation of GAP conductor
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Excellent Sag properties not only compared to conventional conductors, but also amongst the HTLS conductors family.
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Learnings from the project
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Not difficult to execute, same efforts as a normal conductoring job of Conventional Conductor
Only precision in handling of conductor is required
Special Tools and Plants require one time training for manpower
Initial execution takes time, but productivity improves with expertise and experience
Profitable compared to normal conductoring job with same resources applied
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Future Prospects of HTLS conductors
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KEC International has been recently awarded with the reconductoring
project of 132 kV Jeerat – Dharampur Line (8.2 Kms) & 132 kV Dharampur –
Titagarh Line (27.52 Kms) from WBSETCL
Based on our Learning's from previous projects, execution will be
completion within scheduled time frame
Many Existing Lines in India today facing a problem of over loading (28 lines
as per POSOCO data (2013) , approx. 2900kms of network) and increasing
Solution in hand – Big market potential for Re - conductoring projects
Increasing supplier base for HTLS conductors across world
THANK YOU
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The secret of change is to focus all of your energy, not on fighting the old, but in building the new.
- Socrates
Vimal Gupta KEC International Limited
KEC International Ltd. 04/12/2014