Modified Part 2 Tender Document - Naya Raipur

NRDA F-1- Schedule-D- Section III- Technical Specification of Works
Construction of Forest and Water Resources department buildings, North Block at Naya Raipur
NRDA
B. HIGH TENSION CABLES
1. General
The high tension cables used in this assignment shall be three core aluminum conductors. The
conductor of the cable will be made from multistranding of round wires of high purity, high
conductivity, electrical grade aluminium. The cables shall confirm to IS: 7098 (latest edition) and
the following details.
2. Rating
The cables shall be rated for use an earthed 33 KV system and should stand 17 KV for 5 minutes with
insulation break.
3. Core identification
Cores shall be identified by numbers 1, 2 & 3 printed on the insulating.
4.a)
Insulation
The cable will have high quality cross linked Poly Urethane, unfilled compound insulation extruded
over the conductor by a continuous vulcanizing process having arrangement for chemical cross linking
of the compound.
b) Shielding
To avoid electrical point stresses the conductor and the outer surface of the insulation layer should
be shielded by a semi-conducting compound.
c) Inner Sheathing
The insulated conductor and the non hydroscopic gap fillers will be enveloped in either an extruded
layer of compound .
d) Aumouring
Over the sheath a layer of hot dipped galvanised steel strips will be laid to provide the armouring to
the cable. To avoid the armour heating due to induced currents the armouring should be of non
magnetic metal like aluminium or copper alloys in case of single core cables.
e) Outer Shielding
To protect and fix the armouring and to make the handling easy a tough black coloured stabilized
weather resisting grade of PVC is to be extruded over the cable.
5. Current Rating:
The current rating shall be based on the following conditions.
Page 14 of 174