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Signalling/Power Cables

PVC Insulated Armoured Unscreened Underground Railway Signalling Cable
 Specification No. : IRS : S 63/2007 & IS:1554 (Pt.-1) with latest amendment.
Sl.  No.
Description
1.0
SCOPE :

1.1

This specification covers the requirements and tests for armoured and unarmoured single core, twin core, three core and multi-core copper conductors pvc insulated and sheathed cables for railway signaling. This specification covers the complete requirement of underground (u/g), unscreened (u/s), railway signalling cable..
1.2
The cable covered in this specification shall be suitable for use on AC systems (earthed or unearthed) for rated voltages upto & including 1100 volts. These cables may be used on DC systems for rated voltages upto and including 1500 volts to earth. 
1.3
The cables covered in this specification or suitable for use where the combination of ambient temperature and temperature rise due to load results in a conductor tempretaure not exceeding 70°C.
2.0
GENERAL REQUIREMENTS :
3.0
CONDUCTORS :
3.1
The conductor shall be composite of plain, annealed high conductivity copper wire (s) complying with IS:8130 except for annealing test requirements. This diamensions, nominal weights and resistance of conductor shall be in accordance with the values given in Table-1. Any other sizes may be accepted as agreed between the purchaser and the manufacturer. In such cases, the wire diameter, the insulation thickness and the tolerances thereon shall be specified by the purchaser.
4.0
INSULATION :
4.1
The insulation shall be of PVC compound conforming to the requirements of Type ‘A’ compound of IS:5831-84. (General purpose insulation for maximum rated conductor temperature 70°C operation) except for insulation resistance, tensile strength and percentage elongation. Re-cycled or re-claimed material shall not be used.
4.2
The insulation shall be applied by extrusion in one continues process and shall be homogeneous and free from any joints or repairs it shall fit closely on the conductor but shall not adhere to it so that it is possible to remove it easily, without damage to the conductor.
4.3
The cores of cables shall be identified by different colouring of PVC insulation. The colours shall conform reasonably with the standard colours shown in IS:9938. The following colour scheme shall be adspted :-
 
1 Core  - Red, black, yellow, blue or grey.
2 Core  - Red and black.
3 Core  - Red, yellow and blue.
4 Core  - Red, yellow, blue and black.
5 Core  - Red, yellow, blue, black and grey.
6 Core  - Two adjacent cores ( counting and direction core) in each and above layer, blue and yellow, remaining cores grey.

Note :  For a single core in the centre of a multi core cable, red or black colour shall be used. For 2, 3, 4, or 5 centre cores, the colours shall correspond to these specified for 2, 3, 4, or 5 core cable respectively.
4.4

Alternatively the cores of cables with six core and above may be identified by numbers 1, 2, 3, 4, 5 …………Printed indelibly at intervals of not more than 50 mm.

In that case, the insulation of cores shall be of grey colour and printing of number shall be black. The core shall be numbered sequentially in clock wise direction, starting with number 1 for the inner layer. Thenumbers shall be printed in the Hindu-Arbic numerals on the outer surface of the cores. The numbers shall be legible. The consecutive number shall be inverted in relation to each other .When the number is a single numeral, a dash shall be placed underneath it. If the number consist of two numerals, these shall be disposed one below the other and a dash shall be placed below the numerals.       
5.0
LAYING UP :
5.1
The cores of twin three and multi-core cables shall be laid-up together with suitable lay. The outermost layer shall have right hand lay and the successive layers shall be laid with opposite lay. Way of counting from inner to outer layer continuously shall be unidirectional. Where necessary, the interstices shall be filled with non-hygroscopic material. 
5.2
A Malinex tape / Polyester tape of thickness 0.025mm shall be applied helically with left hand lay with minimum overlap of 30% over the laid up cores where DST armouring is provided.
6.0
INNER SHEATH (Common Covering) :
6.1
The laid up cores shall be provided with an inner sheath applied by extrusion. It shall be ensured that it is a circular as possible.
6.2
The Inner sheath shall be so applied that it fits closely on the laid up core and it shall be possible to remove it without damage to the insulation.
6.3
PVC used shall meet the requirements of type ST-1 (General purpose sheath for use at maximum rated conductor temp. 70°C) compound of IS:5831-84. Re-cycled or Re-claimed material shall not be used.  The Colour of the PVC for Inner Sheath shall be Grey.
7.0
ARMOURING :
7.1
Armouring shall be applied over the insulation in case of single core cables and over the inner sheath in case of twin, three and multi-core cables.
7.2

Armouring shall consist of the following :

  1. Galvanised round steel wire to IS:3975 with exception to tensile strength and percentage elongation, or
  2. Galvanised double steel tape to IS:3975 with exception to tensile strength and percentage elongation or
  3. Any other material (as agreed between the purchaser and the manufacturer)
7.3

Where the calculated diameter below armouring does not exceed 13mm, the armour shall consist of galvanized round steel wires only. Wire armouring shall be applied below 12 Core of 1.5 mm² conductor nominal cross sectional areas.
12  core and above of 1.5 mm² of any other sizes of conductor where the calculated diameter below armouring is greater than 13mm, the armouring shall consist of Double Steel Tape.

8.0
OUTER SHEATH :
8.1
The outer sheath shall be applied by extrusion in one continuous process and shall be homogeneous and free from joints and repairs.PVC compound conforming to the requirements of Type ST-1 compound to IS:5831-84. except for tensile strength, percentage elongation and shrinkage shall be used for outer sheath. The colour of the outer sheath shall be black. Re-cycled or Re-claimed material shall not be used.
9.0
MARKING :
9.2

The following information shall be legibly and indelibly indicated throughout the length of the cable by embossing them on the outer sheath at every one meter having letter height not less than 3 mm in case of cables upto 6 Core and 5 mm in case of cables more than 6 Core.

  • Name or trade mark of the manufacturer
  • IRS Specification Number.
  • Month and Year of Manufacturer.
  • Drum Number.
  • Size of the cable (e.g. 12 C x 1.5 sq. mm)
  • Sequential length marking at every meter with an accuracy of ± 0.2%.
9.2
Finished cable is being supplied in non returnable wooden drum

 

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