Part 3: Employer’s Requirements 553

15. LT upto (1100 V) XLPE Insulated

1.0 SCOPE:

1.1 The scope of this specification covers the design, manufacture inspection and testing
the finished ISI marked LT (1100 volts, 31/2 x25 Sq.mm to 400 Sq.mm stranded,
compact aluminum conductor, with XLPE insulated, PVC inner sheathed, galvanized
steel strip armored/unarmored and overall PVC sheathed Black colour cable
conforming to IS:7098 /88 with latest amendments and as per specification detailed.

2.0 RATED VOLTAGE:

2.1 The rated voltage of the cable shall be 1100 Volts AC with the highest system voltage
of 1100 Volts between phases of the effectively earthed three-phase transmission
system.

2.2 The cables shall be capable of operating continuously under the system frequency
variation of ± 3 Hz, voltage variation of ± 10% and a combine d frequency – voltage
variation of ± 10%.

3.0 APPLICABLE STANDARDS:

i) Unless otherwise stipulated in the specifications, the latest version of the following
Standards shall be applicable:

IS 7098 (Part 2)-Cross-linked Polyethylene insulation for Cables.

IS 8130-Conductors for insulated electrical cables and flexible cords.

IS 10810(series)-Methods of tests for cables.

IS 10418-Drums for electric cables.

IS 3975-Specification for mild steel wires, strips and tapes for armouring of cables.

IS 5831-Specification for PVC insulation sheath for electric cables.

Part 3: Employer’s Requirements 554
IS 10462-Fictitious calculation method for determination of dimensions of protective
coverings of cables Part 1 - Elastomeric and thermoplastic insulated cables.

ii) The cables manufactured to any other International Standards like BSS, IEC or
equivalent standards not less stringent than Indian Standards are also acceptable. In
such cases the Manufacturer shall enclose a copy of the equivalent international
standard, in English language.

4.0 CONSTRUCTION:

4.1 Conductor: - The cable conductor shall be made from stranded aluminum to form
compact sector shaped conductor having resistance within the limits specified in
IS:8130/1984 and any amendment thereof. The wires shall be laid up together with a
suitable right hand lay. Stranded Class 2 – as per the IS:8 130 / IEC 60228/ BS 6360
standards.

4.2 Insulation: - The insulation shall be cross linked polyethylene applied by extrusion
and shall be steam (wet) cured as pre IS:7098(1)1988 and curing in hot water tank/bath
is not accepted.:

Sl.No. Properties Requirements

1. Tensile Strength 12.5N/mm², Min.

2. Elongation to break 200 percent, Min

3. Aging in air oven:

a) Treatment: Temperature: 135±3°C
Duration: 7 days
b) Tensile Strength variation: ±25 percent, Max
c) Elongation variation: ±25 percent, Max
4. Hot set:
a) Treatment: Temperature: 200±3°C
Time under load 15 min
Mechanical stress 20N/cm²
b) Elongation under load 175 percent, Max
Permanent elongation (set) after
c) cooling 15 percent, Max

5. Shrinkage:
Part 3: Employer’s Requirements 555
a) Treatment: Temperature 130±3°C
Duration 1 hour
b) Shrinkage 4 percent, Max
6. Water absorption (Gravimetric):
a) Treatment: Temperature: 85±2°C
Duration 14 days
b) Water absorbed 1 mg/cm², Max
7. Volume Resistivity
a) at 27°C 1x1014 ohm-cm, Min
b) at 70°C 1x1013 ohm-cm, Min
8 Thermal Resistivity 350 degrees C cm/W

9 Power factor at maximum conductor 0.008

temperature
10 Dielectric strength 22 kV/mm

4.3.1 The XLPE insulation should be suitable for specified 1.1 KV system voltage.

4.3.2 The manufacturing process shall ensure that insulations shall be free from voids.

4.3.3 The insulation shall withstand mechanical and thermal stresses under steady state and
transient operating conditions.

4.3.4 The insulation of the cable shall be high stranded quality, specified in IS:7098 (Part-
II/1985). Withstand continuous conductor temperature of 90 deg C, which means
higher continuous rated current carrying capacity.

4.3.5 The cables can operate even at conductor temperature of 130 deg C continuously and

250 deg C during a Short Circuit condition

4.4 SHEATH :
The sheath shall be suitable to withstand the site conditions and the desired
temperature. It should be of adequate thickness, consistent quality and free from all
Part 3: Employer’s Requirements 556
defects. The PVC sheath shall be extruded as per IS:7098 (Part – I/1988). IEC:60502
Part– I,BS:6622, LSOH to BS:7835.

4.5 ARMOUR :
Armoring shall be applied over the inner sheath with single galvanized steel
complying with the requirements of IS:3975/1979. The dimensions of the galvanized
strip shall be as specified in table 4 of the IS:7098/Part-I/1988. The armour wire shall
be applied as closely as practicable. The direction of the lay of the armour shall be left
hand. The joints in armour wire shall be made by brazing or welding and the surface
irregularities shall be removed. A joint in any wire shall be atleast 300mm from the
nearest joint in any other armour wire in the complete cable and shall be as per IS:7098
Part 1, IS: 3975.

The cable without armouring shall also be accepted of type detailed in price schedule.

4.6 OUTER SHEATH : Extruded PVC ST2, outer sheath as per IS:5831/1984, IS:7098

Part 1, IEC:60502 Part – 1, BS:6622, LSOH to BS:78 35. shall be applied over
armoring with suitable additives to prevent attack by rodents and termites. Outer
sheathing shall be designed to offer high degree of mechanical protection and shall
also be heat, oils, chemicals, abrasion and weather resistant. Common acids, alkalis,
saline solutions etc., shall not have adverse effects on the PVC sheathing material used.

4.7 The cables should be suitable for use in solidly earthed system.

4.8 The power cables shall be manufactured to the highest quality, best workmanship with
scientific material management and quality control. The Manufacturer shall furnish the
quality plan, giving in detail the quality control procedure / management system.

4.9 The cable shall be suitable for laying in covered trenches and/or buried underground to
meet the outdoor application purposes.

4.10 The parameters of the LT power cables to be supplied shall be as specified below

Nom. AC current
Nom. cross Armoured Max.DC
Thickness rating
sectional
of XLPE Nom. Approx. Approx, Conductor In
area In air
Insulation Steel Overall Weight Resistance Grpund
(Sq.mm) o (amps)
mm main Armour dia. (kg/km) at 20 C (amps)
Part 3: Employer’s Requirements 557
core size (mm) (ohm/km)
(mm)

25 0.90 4 X 0.8 22.8 821.0 1.200 95 97

35 0.90 4 X 0.8 24.9 961.0 0.868 117 116
50 1.00 4 X 0.8 28.1 1195.0 0.641 140 134
70 1.10 4 X 0.8 33.0 1569.0 0.443 176 167
95 1.10 4 X 0.8 35.8 1903.0 0.320 221 199
120 1.20 4 X 0.8 39.0 2303.0 0.253 258 227
150 1.40 4 X 0.8 42.9 2720.0 0.206 294 255
185 1.60 4 X 0.8 47.5 3276.0 0.164 339 287
240 1.70 4 X 0.8 52.7 4048.0 0.125 402 333
300 1.80 4 X 0.8 58.4 4872.0 0.100 461 375
400 2.00 4 X 0.8 65.6 6101.0 0.0778 542 426

4.11 The short circuit current of the LT cable to be as specified below

Sq.mm of LT Cable Short Circuit Current(KA)

25 2.420
35 3.370
50 4.790
70 6.680
95 9.030
120 11.400
150 14.200
185 17.500
240 22.600
300 28.200
400 37.600

5.0 SYSTEM DETAILS:

Part 3: Employer’s Requirements 558
General Technical particulars
Nominal system voltage (rms) (U) 0.44KV
Highest system voltage (rms) (Um) 1.1 KV
Number of Phase 3
Frequency 50Hz
Variation in Frequency +/- 3%
Type of Earthing Solidly Earthed
Total relay & circuit breaker Operating time 15 – 20 cycles

6.0 CLIMATIC CONDITIONS:

(a) Maximum ambient air temperature (in shade) 450 C

(b) Maximum ambient air temperature (under sun) 500 C
(c) Maximum daily average ambient air temperature 350 C
(d) Maximum yearly average ambient air temperature 300 C
(e) Maximum humidity 100%
(f) Altitude above M.S.L. Up to 1000M
(g) Average No. of thunder storm days per annum 50
(h) Average No. of dust storm days per annum Occasional
(i) Average No. of rainy days / annum 90
(j) Average Annual Rain fall 925mm
(k) Normal tropical monsoon period 4 months
(l) Maximum wind pressure 150 kg/Sq.M

7.0 DESIGN CRITERIA:

i. The cables that are covered in these specifications are intended for use outdoor , under
the climatic conditions and installation conditions described in the technical
specification.

ii. For continuous operation of the cables, at specified rating, the maximum conductor
temperature shall be limited to the permissible value as per the relevant standard,
generally not exceeding 90°C under normal operation and 250°C under short – circuit
conditions.

iii. The cables in service will be subject to daily load cycles, of two peaks during a day;
morning peak and evening peak, with around 25% to 50% loading during the nights.

iv. The materials used for outer sheaths shall be resistant to oils, acids and alkalis.
Part 3: Employer’s Requirements 559

v. The cables shall have the mechanical strength required, during handling and laying.

vi. The cables shall be designed to withstand the thermo-mechanical forces and electrical
stresses during normal operation and transient conditions.

vii. The cables shall be designed to have a minimum useful life span of Thirty-five years.

viii. The detailed design drawings shall be submitted along with Purchase order.

8.0 MANUFACTURE PROCESS:

Cross-linking of the insulation materials (pre compounded polyethylene) shall be

conforming to IS: 7098 (Part – II) and the proof of purchase of the above insulating
material shall be submitted and is to be offered for stage inspection..

9.0 MATERIALS:

9.1 Conductor: -The conductor shall be of stranded construction. The material for
conductor shall consist of the plain aluminum of H2 or H4 grade as per clause – 3 of IS
8130/ 1984.

9.2 The minimum number of wires shall be 53 for circular compacted 400 sq. mm
aluminum conductor as per table – 2 of IS 8130/ 1984.

10.0 CORE IDENTIFICATION:

10.1. The core identification for 31/2 core cables shall be provided, by suitable means, like,
by application of individual colour or colored stripes, or by numerals or by printing on
the cores as per clause 13 of IS: 7098 - Part 2

10.2. For identification of different coloring of XLPE Insulation, or by using colored strips,
red, yellow and blue colors respectively shall be used to identify the phase conductors.

11.0 LAYING UP OF CORES:

The cores shall be laid together with a suitable right hand lay. The interstices at the
center shall be filled with a non- hygroscopic material.
Part 3: Employer’s Requirements 560
12.0 INNER SHEATH (COMMON COVERING):

12.1 The laid up cores shall be provided with inner sheath applied either by extrusion. It
shall be ensured that the shape is as circular as possible. The inner sheath shall be so
applied that it fits closely on the laid up cores and it shall be possible to remove it
without damage to the insulation.

12.2 The thickness of the inner sheath (common covering) shall be given as follows:

CALCULATED DIAMETER IN MM
OVER LAID UP CORES [REF IS 10462 THICKNESS OF INNER
(PART 1)] SHEATH (Min) mm
Over Up to and including
_ 25 0.3
25 35 0.4
35 45 0.5
45 55 0.6
55 _ 0.7

12.3 When one or more layers of binder tapes are applied over the laid up cores, the
thickness of such tapes shall not be construed as a part of inner sheath.

13.0 ARMOURING:

13.1 Armouring shall be single strip steel wire applied over the inner sheath as closely as
practicable. The direction of the lay of the armour shall be left hand.

13.2 The armour shall consist of galvanized strip steel The dimensions of the galvanized
steel wires shall be 4 X 0.8 mm (Nominal)

13.3 The joints in the armour strip shall be made by brazing or welding and the surface
irregularities shall be removed. A joint in the wire shall be at least 300-mm from the
nearest joint in any other wire in the complete cable.

13.4 Manufacturers shall furnish the calculation / data sheet for the short circuit carrying
capability of the Armour.

14.0 OUTER SHEATH:

14.3 The outer sheath shall be applied by extrusion. It shall be applied over the armouring
Part 3: Employer’s Requirements 561
shall consist of poly-vinyl chloride (PVC) compound, conforming to the requirements
of type ST-2 of IS 5831. Suitable additives shall be added to give anti termite
protection.

14.4 The minimum thickness of the PVC outer sheath shall be as per IS:10462 and as
detailed.

Calculated diameter under the outer sheath [IS 10462

Part 1] – mm Nominal thickness of the
outer sheath (ts) - mm
Over Up to and including
_ 15 1.24
15 25 1.40
25 35 1.56
35 40 1.72
40 45 1.88
45 50 2.04
50 55 2.20
55 60 2.36
60 65 2.52
65 70 2.68
70 75 2.84
75 _ 3.0

14.5 IDENTIFICATION:

The outer sheath shall have the following information embossed or indented on it; ISI
marking, the manufacturer’s name or trade mark, the voltage grade, the year of
manufacture and the letters “RDSS, Name of Employer” The identification shall repeat
every 300/350mm along the length of the cable. Outer sheath of cable shall be black in
permanent colour.

15.0 INSPECTION AND QUALITY CONTROL:

The Manufacturer shall furnish a complete and detailed quality plan for the
manufacturing process of the cable. All raw materials shall conform to relevant
applicable standards and tested for compliance to quality and requirement. During the
manufacturing process, at all stages, inspections shall be made to check the physical
and dimensional parameters, for verification to compliance to the standards. The
Manufacturer shall arrange, for inspection by the purchaser, during manufacture with
Part 3: Employer’s Requirements 562
one month advance notice for verifying the various stage inspections as specified in the
quality assurance plan enclosed to verify the quality control process of the
Manufacturer.

16.0 TYPE TESTS:

Type test certificates from Accredited NABL Testing Laboratories for 1.1 kV XLPE,
shall be submitted along with Purchase order. The Type Tests should have been
conducted not later than 5 years as on the date of supply.

16.1 Stage wise Inspection: The Manufacturer shall offer the stage wise inspection as
detailed in the in the quality assurance plan

16.2 All acceptance tests shall be conducted in the presence of the Employer’s
representative.

16.3 The supplier shall give 10 days advance notice for inspections, and witnessing of tests
by the Employer representative.

16.4 The following type tests shall be conducted on the cable.

Test method
Sl. No. Test Requirement Ref Part no of
IS: 10810
a) Tests on conductor
i) Tensile test IS:8130 2
ii) Wrapping test IS:8130 3
iii) Resistance test IS:8130 4
Clause 15.2 &
36 to 42
b) Tests for armoured wires and strips IS:3975
Clause 4.3, 14.2
6
c) Test for thickness of insulation and &
sheath 16.2
d) Physical tests for insulation: Clause 4.2
i) Tensile strength and elongation at 7
break
ii) Aging in air oven 11
iii) Hot test 30
iv) Shrinkage test 12
Part 3: Employer’s Requirements 563
v) Water absorption (gravimetric) 33
e) Physical tests for outer sheath IS: 5831
i) Tensile strength and elongation at 7
break
ii) Aging in air oven 11
iii) Shrinkage test 12
iv) Hot deformation 15
f) High voltage test Clause 22.7 45
g) Flammability test Clause 22.8 53

17.0 ACCEPTANCE TEST:

17.1 The sampling plan for acceptance test shall be as per IS 7098 part -II, Appendix ‘A’.

17.2 The following shall constitute the acceptance test.

a. Tensile test for aluminum.

b. Wrapping test for aluminum.

c. Conductor resistance test.

d. Test for thickness of insulation.

(i) Test for thickness of inner and outer sheath.

(ii) Hot-set test for insulation.

(iii) Tensile strength and elongation at break test for insulation and outer sheath.

(iv) High voltage test.

(v) Insulation resistance (volume resistivity) test.

18.0 ROUTINE TEST:

The following shall constitute routine tests:

o Conductor resistance test.

o High voltage test.

Part 3: Employer’s Requirements 564

19.0 DETAILS OF TESTS:

19.1 Unless otherwise mentioned in this specification, the tests shall be carried out in
accordance with appropriate part of IS: 10810.

19.2 High Voltage Test at room temperature:

The cables shall withstand a voltage of 3KV AC (rms) at a frequency of 40 to 60 Hz or

an AC voltage of 7.2kV , between conductors and between conductors and ECC ( if
any) for a period of 5 minutes each test connection.

19.3 Flammability test: Period of burning after removal of the flame shall not exceed 60
seconds and the unaffected (uncharred) portion from the lower edge of the top clamp
shall be at least 50-mm.

Employer reserves the right to select a random sample of 1.1 kV UG cable from the
Manufacturer’s end which are ready to dispatch and also ongoing cable laying works
and the same samples will be sent to any testing laboratory as desired by Employer. If
the testing results are found to be not satisfactory Employer reserves the right to reject
the entire batch of cable received and insists for replacement of material free of cost.
The decision of Employer in this regard is final.

20.0 PACKING:

20.1 The cables, as per specified delivery lengths, shall be securely wound /packed in non-
returnable wooden drums, capable of withstanding rough handling during transport by
Rail, Road, etc. The packing should withstand storage conditions in open yards. The
cable drums shall conform to IS 10418-1982 or equivalent standard. The dimensional
drawings of wooden drums shall be furnished with the Purchase order. The drum shall
be provided with circumferential lagging of strong wooden planks. The end of the
cable shall be sealed with good quality heat shrink sealing caps. The sufficiently
required additional sealing caps shall be supplied for use of testing during laying and
jointing at site and to seal spare lengths of cable. The packing should be able to
withstand the rigorous of transport. The following information in bold letters in
English shall be painted on the flanges.
Part 3: Employer’s Requirements 565

a. Name & Address of the manufacturer, Trade name/Trade mark/Brand

b. ISI Marking

c. Size of cable (Cross section) rated voltage, standard, insulation, cable code,
drum No., and year of manufacture.

d. Length of cables (Meters)

e. Direction of rolling
i) Net weight (in Kg)

ii) Gross weight (in Kg)

iii) Owners purchase order reference.

21.0 SEALING OF CABLE ENDS ON DRUMS:

21.1 The cable ends shall be sealed properly so that ingress of moisture is completely
prevented. The individual core endings shall be sealed effectively with water resistant
compound applied over the core and provided with a heat shrinkable or push-on or
Tapex or cold shrinkable type cap of sufficient length with adequate cushion space so
that the conductor does not puncture the cap in case of movement of the core during
unwinding or laying. Before sealing, the semi conducting layer on the cores may be
removed for about 2 mm at each end, to facilitate checking the insulation resistance
from one end, without removing the sealing cap at the other end.

21.2 The three cores should have an overall heat shrinkable or push-on or Tapex or cold
shrinkable type cap with adequate end clearance, and sufficient cushioning to prevent
puncturing of the overall sealing cap due to stretching of the cores. The sealing cap
shall have sufficient mechanical strength and shall prevent ingress of moisture into the
cable. The ends of single core cables shall also be sealed on the same lines to prevent
entry of moisture.

22.0 CABLE LENGTHS:

The cables shall be supplied in continuous lengths of 500 m or more with 5% tolerance
and cable shall on the wooden drums only.
Part 3: Employer’s Requirements 566
23.0 QUANTITY TOLERANCE:

A +3% tolerance shall be allowed on the ordered quantity including 300-m cable as
spare.

24.0 MARKING:

24.1 The packed cable drum shall carry the following information, clearly painted or
stenciled.

a. The letters ‘RDSS, Name of Employer’

b. Reference to Standard and ISI mark.

c. Manufacturer’s Name or trade mark.

d. Type of cable & voltage grade.

e. Number of cores.

f. Nominal cross- sectional area of conductor.

g. Cable code.

h. Length of cable on the drum.

i. Direction of rotation.

j. Gross weight.

k. Country of Manufacture.

l. Year of Manufacture.

m. Purchase order and date.

n. Address of consignee.
25.0 GUARANTEED TECHNICAL PARTICULARS:

The manufacturer, shall furnish the guaranteed technical particulars of the cable
Part 3: Employer’s Requirements 567
offered in the GTP format provided.

26.0 DRAWING & LITERATURE:

(i) The following shall be furnished along with the tender

Cross sectional drawings of the cables, giving dimensional details.

An illustrated literature on the cable, giving technical information, on current ratings,

cable constants, short circuit ratings, de rating factors for different types of installation,
packing date, weights and other relevant information.

27.0 GUARANTEE: The cable manufactured shall be guaranteed for the period of 18
months from the date of receipt at stores.

28.0 The Manufacturer shall furnish a copy of valid BIS licence for ISI marking without
which the cable shall not be accepted.

GUARANTEED TECHNICAL PARTICULARS FOR 1.1 KV

Manufacturer's Name
Class of Power Cable

1
Name of the Manufacturer and country of origin
2 Country of Manufacture
3 Type of cable / cable code
4 Applicable standard
Voltage
5 a. Rated Nominal voltage
b) Rated Maximum voltage
Suitability for :
6
a. Earthed system
Conductor
a) Nominal cross section (sq.mm)
7 b) Material
c) Shape
d) Diameter of conductor (mm)
Part 3: Employer’s Requirements 568
e) Number of wires per conductor (Nos.)
f) Nominal diameter of wire in conductor (mm)
Insulation XLPE
a) Curing process (furnish details separately)

b) Material/Composition

8
c) Dia over insulation

i. Nominal (mm)
ii. Average (mm)
iii. Minimum (mm)
Inner sheath
a) Type / composition
9 b) Material
d) Tolerance on thickness
e) Diameter of cable over sheath (mm)
Armouring
a) Material
10 b) Dia of wire
Nom. (mm)
Min. (mm)
Outer sheath
a) Type / composition
b) Material
11
c) Nominal thickness
d) Tolerance on thickness
e) Diameter of cable over sheath (mm)
Anti-thermite treatment to outer sheath
a) Material
12 External overall dia of cable
Short circuit rating of conductor 90 deg. C
operating temperature for 1 Sec.
Minimum cable bending radius (in terms of
13
cable diameter)
14 Permissible maximum tension
Continuous current rating under specified
15
insulation conditions at conductor temperature of 65
Part 3: Employer’s Requirements 569
deg. C and 90 deg. C.
16 Ground Temperature 30 deg. C
17 Thermal resistivity of soil 150 deg. C CM/W
18 Depth of laying 200 mm
19 Ambient Air temperature 40 deg. C
20 No. of circuits 1 OR 2
21 Spacing between two circuits
Formation
22

Maximum permissible conductor temperature for

continuous operation under specified installation
23
conditions (deg. C)

Conductor temperature at rated current (deg. C)

24

Basic impulse level at conductor temperature of 90

25 deg. C (KV)

Impulse wave shape

26

Power frequency with stand voltage (KV)

27

Tan Delta at 50 Hz (at U.KV and 90 (-5/+10) deg.

28
C
Sheath voltage at max. load
29

Withstand voltage of sheath on spark test

30

Permissible short circuit current ratings of

conductor

31 i) 0.1 Sec KA
ii) o.2 Sec KA
iii) 0.5 Sec KA
iv) 1.0 Sec KA
Conductor resistance DC & AC
a) at 20 deg. C (d.c)/A.C. ohm/KM
32
b) at 90 deg. C (d.c)/A.C. ohm/KM
c) at 105 deg. C (d.c)/A.C. ohm/KM over load
Part 3: Employer’s Requirements 570
temp) a.c. (ohm)
Equivalent star resistance at 50 Hz of 3
phase current
a) at 20 deg. C (d.c)/A.C. ohm/KM

33 b) at 90 deg. C (d.c)/A.C. ohm/KM

c) at 10% continuous overload temperature

(ohm/KM)

Star reactance at 50 hz (ohm/KM)

Approximate impedance at 50 hz per KM

34
a. at 20 deg. C ohm/KM
b. at 90 deg. C ohm/KM
c. at 10% continuous overload temperature
(ohm/KM)
Self-electrostatic capacitance per phase (Micro
35
farad/KM)
Maximum power factor at charging KVA of cables
when laid direct in ground at normal voltage &
frequency
36
a) at ambient Temperature

b) at Maximum conductor Temperature

Impedance

a) Positive and negative sequence impedance 37

(ohm/KM)
37
b) Zero sequence impedance (ohm/KM)

c) Zero sequence data

Series reactance / Resistance

38
a) Series resistance (ohm/KM)
Part 3: Employer’s Requirements 571
Series reactance (ohm/KM)

Shunt capacitive reactance (ohm/KM)

Sheath resistance at 20 deg. C ohm/KM

39
Surge impedance of cable (ohm/KM)
40
IR value at amient temperature per KM

Maximum magnitude of partial discharge at 1.5 U.o

At Ambient Temperature (Po)

At High Temperature (Po)
Losses per Km.

NOTE : (i) Cable Conductor size 400 sq. mm

a) Total 3 phase dielectric loss

41

i. One circuit alive Kw/KM

ii. Both circuits alive KW/KM on each circuit

b) Total 3 phase resistive loss
i. One circuit alive Kw/KM

ii. Both circuits alive KW/KM on each circuit

c) Total 3 phase sheath / screen loss
i. One circuit alive Kw/KM

ii. Both circuits alive load KW/KM on each circuit

d) Other losses due to reinforcement
42
43 One circuit alive KW/KM
Both circuits alive KW/KM on each circuit
Total losses
44 i. One circuit alive KW/KM

ii. Both circuits alive KW/KM

Part 3: Employer’s Requirements 572
Charging current at rated voltage per Km
(Amps)
Short circuit capacity of conductor for one
second at 90 deg. C prior to short circuit and 250
45 deg. C during short circuit (KA)
Screening factor of cable for calculating
interference on control and communication cables
:
Approximate value of attenuation of carrier
46 current signals operating over a frequency range
i. 50 KC/s- dB/KM
ii. 100 KC/s- dB/KM
iii. 150 KC/s- dB/KM
iv. 200 KC/s- dB/KM
Shipping weight and size of cable drum
a) Size of Drum
i. Dia of Drum (M)
47 ii. Width of Drum (M)
iii. Gross Weight (Kgs)
iv. Length of cable per Drum(M)
v. Weight of Cable (Kg/M)

Current Rating Factor

Single Point Bonded Both End Bonded

Particulars 65 deg. C 90 deg C 65 deg. C 90 deg. C
Amps Amps. Amps Amps
Current Rating conductor size 400 Sq. mm

a) In Ground
i. Of each circuits (when both the circuits
alive)
b) In Duct

i. Of each circuits (when both the circuits

alive)

ii. Of one circuits (when other circuit is

isolated)
Part 3: Employer’s Requirements 573

c) In pipe, one cable per pipe.

i. Of each circuits (when both the circuits

alive)

ii. Of one circuits (when other circuit is

isolated)

d) In Air

i. Of each circuits (when both the circuits

alive)
ii. Of one circuits (when other circuit is
isolated)

Derating Factors

1. VARIATION IN GROUND TEMPERATURE :

Ground Temperature (deg. C) : 15 20 25 30 35 40 45

Rating Factor
2. VARIATION IN DEPTH OF LAYING :

Depth of Laying (Meters): 0.7 0.9 1.0 1.2 1.3 1.5

Rating Factor
3. VARIATION IN THERMAL RESISTIVITY OF SOIL

Thermal Resistivity of Soil : (deg. C cm/watt) 100 120 150.0 200 250
Rating Factor

4. VARIATION IN AIR TEMPERATURE :

Air Temperature (deg. C) : 25 30 35 40 45 50 55

Rating Factor
5. VARIATION DISTANCE (MM) :

Axial Distance (mm) Between circuits : 100 200 300.0 400 600 800
Rating Factor
Part 3: Employer’s Requirements 574