11KV ABC cable current carrying capacity

Let us discuss about Size and current carrying capacity of a  11 KV 3x120 mm2 AB Cable. Before getting answer we have to know about Technical Specification.The Technical Specification as below.

TECHNICAL SPECIFICATION FOR 11KV AB Cable( AERIAL BUNCHED CABLES)  and XLPE insulated (CROSSED LINKED POLYETHYLENE DRY GAS CURED/WET CURED) FOR OVERHEAD LINES.

1. SCOPE

 This specification covers requirements of XLPE insulated, 11 KV Aerial Bunched Cables for overhead lines.

2. COMPOSITION OF THE CABLE

The composite cable shall comprise three single-core cables twisted around a bare aluminium alloy messenger wire, which will carry the weight of the cable.

3. RATED VOLTAGE

The rated voltage of the cables shall be 6.35KV/11KV and the maximum operating voltage shall be 12 KV.

4. APPLICABLE STANDARDS

Unless otherwise stipulated in this Specification, the following Standards shall be applicable:
i) IS: 7098 (Part-II) - 1985 – Cross linked Polyethylene Insulated PVC Sheathed Cables
ii) IS: 8130-1984 - Conductors for Insulated Cables
 iii) IS: 398 (Part-IV) - 1979 - Aluminium Alloy Conductors
 iv) IEC- 60502 (Part-II) 2005 - Polyethylene Outer Sheath

 5. DETAILS OF SINGLE-CORE CABLE

 5.1 The cable conductors shall be of round, stranded and compacted aluminium of nominal cross sectional area 35mm² / 70 mm2 / 95 mm2 /120 mm2. Corresponding nominal conductor diameter and number of wires in the conductor shall be as given in clause 5.7.
 5.2 Conductor Screen
The conductor screen shall be of extruded semi-conducting cross inked polyethylene compound of thickness not less than 0.5mm.
 5.3 Insulation
The insulation shall be of extruded cross linked polyethylene (XLPE), Dry Gas cured/wet cure process, of nominal insulation thickness 3.6mm and its properties shall conform to IS: 7098
(Part-II).
5.4 Insulation Screen
The insulation screen shall comprise extruded semi-conducting compound and/or  semiconducting tape. Thickness of the screen shall be not less than 0.6 mm.
 5.5 Metallic Screen
The metallic screen shall consist of Copper tape of thickness not less than 0.045mm.
 5.6 Outer Sheath
The outer sheath shall be black polyethylene. The nominal thickness of sheath shall be 2 mm and it shall conform to the technical requirements of ST-7 of IEC-60502 (Part-II) 2005
5.7 Dimensional and Electrical Data
 The dimensional and electrical data for single-core cable is given below:

6. MESSENGER (NEUTRAL CONDUCTOR) 

6.1 The bare messenger wire shall be of 70mm2 / 80mm2 / 100 mm2 (nominal area) aluminium alloy, generally conforming to IS:398 (Part-IV) - 1994, comprising of 7 strands and shall be suitably compacted/non compacted to have smooth round surface to avoid damage to the outer insulating sheath of single-core phase cables twisted around the messenger.

 6.2 There shall be no joints in any wire of the stranded messenger conductor except those made in the base rod or wires before finally drawing. 

6.3 The technical characteristics of the messenger wire shall be as follows: 

7. DESIGNATION AND PARAMETERS OF FINISHED CABLES 

 

The designation and parameters of finished cables are given in the following table: 

Note: The first part of the designation refers to the number and size of phase conductor and the second to the size of messenger wire. The sizes shown represent the nominal cross sectional areas in mm.

Answer:.As per above we know that Current carrying capacity of 3x120 mm2 Cable is 260 Amp and dia is 67 mm