Presented at Sterlite office

2.  M/s Sterlite Grid Limited faced a problem in
400kV D/C Quad Transmission Line Bongaigon
to Siliguri.
 Un-Compressed zone of Compression type
dead end sleeve are elongated in line.
 One of the supplier wrongly supplied EC Grade
Dead End Sleeve in place of Al.Alloy Sleeve.
 Conductor Used In Line :AAAC 525 Sq.mm
 Overall Diameter : 29.79 mm
 Minimum UTS : 146.03 kN

3. 1. Due to lower Tensile strength rating of EC Aluminium
sleeve, it cant perform that designated mechanical function
of dead ending conductors.
2. While EC sleeve is unsuitable as mechanical member, it
still will function perfectly as a electrical member by
adequately transmitting current to the jumper.
3. Solution lies in physical separation of dead
end assembly parts into mechanical and electrical
components.
4. While the sleeve already installed and this will
continue to function as electrical member, we have to
overlay a mechanical member on the existing installation
which will allow the line to be tensioned with appropriate
factor of safety.

4. QUOTE :9.11.6.1. HELICAL TERMINATIONS
FOR CONDUCTORS (GREEN BOOK 9-50)
 Helical dead-ends are used to terminate
conductors. They have been used successfully for
the past 40 years.
 The typical device is designed to hold the
mechanical load of the conductor and is not
designed to transfer electrical loads.
 Most helical terminations for smaller ACSR and
conductors of homogeneous construction (such as
AAAC or AASC.
 The structural reinforcing rod layer is similar to an
armour rod layer and increases the contact length
of the dead end.

5.  The second layer is a helical termination that is wrapped
over the structural reinforcing layer.
 The helical termination is designed such that the bore of
the helical wrap is smaller than the diameter of the
conductor. This results in compressive force being applied
to the conductor along the contact length of the product.
 The helical termination only contacts the out side layer of
the conductor.So it must pass the compressive load into
the inner layer of the conductor.
 In case of multi-layer ACSR,the helical dead end cannot
pass enough holding strength onto the core to develop
90% RTS of the conductor. In these cases, specially
designed two layer helical termination may increase the
holding strength above the 95% RTS level.

6. DRAWING

7. BRIEF TECHNICAL PARAMETERS:
 As suggested in above drawing, we shall use
aluminium alloy re-inforcing rods helically wound
on conductor so that such re-inforced
conductor would be nearly equal to sleeve outer
diameter of compressed portion of dead end.
 Add one more layer high strength aluminium clad
steel looped and helically wound dead-end covering
the entire length spanning the sleeve and re-
inforced portion of conductor.
 We shall install additional corona-ring of smaller
dia of 200 to shield the extended portion.

8. GUARANTEED TECHNICAL PARTICULAR
1. Maker’s Name & Address : Supreme & Co. Pvt. Ltd. P-200 Benaras Road
Howrah 711108
2. Drawing No. : 19003/P (Part -14/1) Date: 19.09.2014
3. Protective Helix Material : High Strength Al.Alloy type 6061
4. No of rods per set : 13
5. Diameter of rod : 7.87mm
6. Length of rod : 2080mm
7. Dead End Grip Materials : Al.Clad Steel wire
8. No of rods per set : 8
9. Diameter of rod : 3 mm
10. Length of Rod : 2740 mm
11. Glue & Grit : Used
12. Grading Ring : Extruded Aluminium tube as per IS 733 or IS 1285 or
Al.Casting IS 617 Gr 4600
13. Packing : In Wooden Crate
14. Corona Extinction Voltage (Under Dry
Condition)
: Minimum Corona Extinction Voltage 320kV (rms) under
dry condition.
15. RIV (Under Dry Condition) Maximum RIV 1000 µV at 305kV (rms) under dry
condition

9. EXPERIMENTAL TYPE (DESIGN) TEST :
 EXPERIMENT NO.: 1 (With Out Steel Sleeve)
 ON A PIECE OF AAAC 525 SQ. MM. CONDUCTOR ONE SIDE
COMPRESSED WITH M/S. SUPREME MAKE COMPRESSION
DEAD END CLAMP & THE OTHER SIDE WERE
COMPRESSED WITH M/S. STERLITE PROVIDED DEAD END
CLAMP WITHOUT STEEL SLEEVE.
 Mechanical Failing Load Test:
 (i) A tensile load of 139KN (i.e 95% UTS of
Conductor) was applied and hold for 5mins.
 Result : No Slip observed
 (ii) Load increased up to 161 KN (i.e 110% UTS of
Conductor ) and hold for 5mins.
 Result : Conductor Strand broken down

10. EXPERIMENT NO.: 2 (WITH STEEL SLEEVE)
 ON A PIECE OF AAAC 525 SQ. MM. CONDUCTOR ONE
SIDE COMPRESSED WITH M/S. SUPREME MAKE
COMPRESSION DEAD END CLAMP & THE OTHER SIDE
WERE COMPRESSED WITH M/S. STERLITE PROVIDED
DEAD END CLAMP WITH STEEL SLEEVE.
 Mechanical Failing Load Test:
 (i) A tensile load of 139KN (i.e 95% UTS of
Conductor) was applied and hold for 5mins.
 Result : No Slip observed
 (ii) Load increased up to 159 KN
 Result : M/s Sterlite provided Dead End Clamp
Broken down from Un- compressed zone.

11.  Successfully passed the Corona & RIV test at Global
Power Research Institute, Cuddalore.
Test Description Standard Requirement Observed Value
Corona Extinction
Voltage Test
(Under Dry
Condition)
IEC 60383-2 /
IEC 61284 &
Customer
Requirements
Minimum Corona
Extinction Voltage
320kV (rms)
under dry
condition
Extinction Voltage
338 kV
RIV Test (Under
Dry Condition)
IEC 60437 /IEC
61284 / IS 8263 &
Customer
Requirements
Maximum RIV
1000 µV at 305kV
(rms) under dry
condition
RIV 224 µV at
305kV

12. ADVANTAGES OF HELICAL DEAD END
 It does not changes the Geometrical Shape of the
conductor
 Same conductor goes to 1st point to last point
 Reduce line man error
 Reduce the chance of wrong grade application of
aluminum
 Eliminate the use of steel sleeve

13. HELICALLY FORMED DEAD END GRIP

19. FITMENT TEST AT LINE:
Protective Helix on
Conductor
Helically formed Dead End
Grip

22. QUESTIONS, COMMENTS, DISCUSSION