1) TPDDL developed the first 3 core 66kV cable globally to address issues with traditional single core cables, such as cable heating, damage, and the need to replace entire cables when faults occurred. 2) Significant challenges were faced in developing specifications and accessories for the new 3 core cable design and in getting manufacturers onboard due to the risks involved. 3) An initial 5km pilot project has been successfully operating for 7 months, demonstrating annual savings of approximately 25 crores INR and benefits like increased system flexibility and reliability. The new cable design is being recognized within the industry and standards organizations.

1. Three Core Extra High Voltage
Cable – A Global Innovation

2. Residential
Consumers
Industrial
Consumers
Generation
220/66 KV
Substation
TPDDL 66/11
KV
Substation
11/0.433 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.

3. Underground 66000 V ,
1C, Cable
Voltage Induction in sheath (V)
Conductor Metallic SheathInsulation
V
Length
Meter
Volts
L
3
Outer jacket
Problems Associated with Single Core Cable

4. Underground
SVL
SVL
Other
Utilities
4
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

5. 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.

6. 66000 V
Substation 1
66000 V
Substation 2
Bonding
Arrangement
Bonding
Arrangement
Problems Associated with Single Core Cable
In Loop In Loop Out

7. 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 Cable
In Loop In Loop Out

8. What is the solution??
FUNDAMENTAL
CHANGE IN THE
DESIGN OF THE
66000 V CABLE

9. 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
Conductor
Insulator
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

10. 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

11. 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?

12. 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?

13. 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.mm
Current 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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14. 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

15. 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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16. Final Cable
 Aerial & front view of the Cable
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17. Experience so far…
5 Km Cable has been
laid as a pilot project &
working satisfactorily
since last seven months
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18. 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

19. 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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20. 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

21. 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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22. Thank You