Three core extra high voltage cable – a global innovation
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Transcript of Three core extra high voltage cable – a global innovation
Residential Consumers
Industrial ConsumersGeneration 220/66 KV
Substation
TPDDL 66/11 KV
Substation11/0.433 KV Distribution Transformer
TPDDL 66000 V Underground network 273 Circuit KM,
3600 MVA, ~ 0.5 Million Consumers
Background
1st 2nd 3rd
Only Single Core cable is being used at 66000 V Level.
Single Core Cables have some inherent issues.
Underground 66000 V , 1C, Cable Voltage Induction in sheath (V)
Conductor Metallic SheathInsulation
V
LengthMeter
Volts
L
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Outer jacket
Problems Associated with Single Core Cable
Underground
SVLSVL
Other Utilities
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Cable gets Heated
Cable gets de-rated
Cable Life Reduces
Cable gets Damaged
• Complete length of the cable becomes faulty.• The complete Cable needs to be replaced by a new
cable.
Problems Associated with Single Core Cable
Impact of Tripping of a 66000 V Circuit
6 Million INR per day – Revenue loss
Whole circuit gets damaged .
Approximately 20 crore INR loss
Approximately 1 Lakh Consumers get affected per
circuit.
66000 V Substation 1
66000 V Substation 2
Bonding Arrangement
Bonding Arrangement
Problems Associated with Single Core CableIn Loop In Loop Out
New 66000 V Substation 3
66000 V Substation 1
66000 V Substation 2
Bonding arrangement to be changed.
It’s a very costly and time consuming job
Problems Associated with Single Core CableIn Loop In Loop Out
Development of 3 Core 66000 V Cable
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Due to its inherent design the 3 core cable has almost nil Sheath Voltage
ConductorInsulator
Metallic Sheath
Outer Sheath
Armour
Inner Sheath
Vector Sum is Zero
Can We move from 3 Core 33000 V to 3 Core 66000 V Cable?
3 Core Cable can be one of the Solution.No Standard
available for 3 Core 66000 V
cable Worldwide
Can We Manufacture 3 Core 66000 V Cable?
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• We Studied Indian Standards for manufacturing cables BIS 7098 part II & part III.
• We also studied Global Standards for Cables, IEC 60840, 60228, 60502.
• American Standard ASTM D2633. • European Standards.
• None of these standards cover 3 Core 66 KV Cable.
No Standard available for 3 Core 66000 V
cable Worldwide
We Decided to make our Own Specification
with stringent testing norms
Issues Faced in Framing the Specifications
The First issue was Sizing of the Cable.
We started by creating conceptual design for 3 Core 1000 Sqmm cable.
But it became very bulky with 29 kg of weight for 1 Mtr. Which can’t be handled by standard machines.
The diameter of the cable was also 170 mm, which is an exceptionally high value and would prove difficult to handle.
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Can we go for Higher
Conductivity Material?
Can we go for higher conductivity material
We also explored possibility of using Copper conductor in place of Aluminum. Weight still was out of limit.
We reached a dead end.
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What Next?Can we go for 2 runs of 3 core
cable in place of 1 run?
Sizing of the cable- Development of 3 Core 66000 V Cable
1. Sizing
2. Three nos. of Single Core Cables are equivalent Two nos. Three Core Cables
Diameter of the new 3 Core 66000 V Cable is 128 mm & Weight is 14 kg /Meter
PARAMETERS 66KV 1 x 1000 sq.mm 66KV 3 x 300 sq.mmCurrent capacity (in
Ground) 600 A 303 A x 2 = 606 A
Diameter & weight of the new 3 Core 66 KV Cable is within standard limits
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Associated Accessories
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These Accessories are not available
Straight Through Joint Kit Termination Kit
TPDDL along with associates developed these accessories with lot of efforts within 3-4 months.
With this concept draft specifications were
finalized for 66000 V 3C X 300 Sqmm cable
Manufactures’ Reluctance
Specifications were shared with the manufacturers & only one associate turned up.
The Reasons were:
1) Huge risk involved as the cost of 1 Mtr 66000 V Circuit is approx. 15000 INR.
2) Resistance to Change
But When we floated the tender all associates participated and finally the order was awarded to one of the associate.
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Experience so far…
5 Km Cable has been laid as a pilot project & working satisfactorily
since last seven months
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Impact of the Development
There is no Voltage on Outer Sheath of 3 Core Cables. so bonding arrangement is not required. And there is no issue of total length of cable getting damaged . This results in annual cost saving of 20 crores INR annually
Cost is less by 5%. This results in annual cost saving of 1.2 crores INR annually
Width of the Trench is less by 15 %. This results in reduction of road restoration charges by 1.12 crores INR annually
Flexibility of system shall increase as Loop in loop out shall become easy by 2.64 crores annually
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Resulting in total Saving of Approx. 25 Crores INR
Annually
Impact of the Development
Double run for single circuit – results in reliability & customer satisfaction without paying any thing extra. Directly linked to brand image of the organization
Only 2 drums required at site instead of three drums as required in single core cable
Laying is very easy & simple, TODAY. As single core cables are laid in trefoil formation with clamps
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Recognition by Industry
Matter was taken up by TPDDL with Bureau of Indian Standards for framing of specifications
CIGRE(The Council on Large Electric System) – IEC has invited TPDDL to discuss the framing of standards for 3 Core EHV Cables in Colloquium 2016 , Montreal, Canada
Central Power Research Institute is updating its testing facility to cater to 3 Core EHV Cables.
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BIS 7098 Part II & Part III are taken up for revision by Bureau of Indian Standard for Three core Extra High Voltage cables
TPDDL’s letter to BIS to take up for spec revision
Excerpts from the MOM of Meeting held with Beureau of Indian Standards
Invitation from CIGRE
Uniqueness & Scalability
Uniqueness : First time implementation across industries, globally.
Scalability : Huge potential for whole distribution and sub-transmission sector world wide. The consumption of 66000 Voltage & above Cable in SAARC nations itself is of 6700 KM, costing 2000 Crore INR.Boon for Smart Cities.
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