Here we want to discuss more on ABC. AS we know in the IPDS scheme we are drawing close to 2 laks kilometer of various AB cables. So lets have a discussion on its various sides.
Design and construction
Messanger
Conductor
a)Aluminum Alloy, Aluminum Conductor, Aluminum Conductor Steel Reinforced
b) Insulation: PVC
11KV ABC Cable:
a) Conductor: Hard Drawn Aluminum
b) Conductor Screen: Semi-Conductive Compound
c) Insulation: Cross-Linked Polyethylene
d) Insulation Screen: Sem-conductive Compound
e) Metallic Screen: Copper Tape
f) Outer Sheath: Black PVC + Ultra Violet Resistant
Semi conducting Layer
The material is a polymer base mixed with a conductivity imparting agents such as carbon black.
Semi-conducting compounds also have the effect of fillings in the interstices of the conductor giving a smooth surface for insulation.
semiconductor behaves as conductors when temperature rises so when the HT cables is on load , Its conductor temperature rises due to this the semicon layer which is on conductor behaves like conductor as a result overall cross-section area is increased
The second silicon layer which is over XLPE on temperature rise behaves a conductor and used for dissipating heat out of conductor as the cable heat due to load. The semi-conductive layer also serves to even out the stresses associated with partial discharge which would otherwise attack the insulation at specific points.
It acts a smooth transition between each layers
It protects XLPE insulation from moisture abosrption.
components of HV ABC
Stranded Aluminium round Phase conductor - IS: 398
• Conductor screen of semiconducting compound (0.5 mm thick)
• Polyethylene (XLPE) Insulation - IS:7098 (Pt-II) (3.14 Min/3.6 Nom
mm thickness)
• Insulation screen (0.6 mm thick)
• Conductors for insulated electric cables and flexible cords - IS:8130
and IS:398
• Copper tape (Min. 0.1 mm thick)( very important- at chimmony the size is .045mm)
• Outer PVC sheath Type ST-7(1.4 Min/2.0 Nom mm thick)-IS: 5831
• Process for both conductor screen and insulation screen which is
semi-conducting compound are extruded and are applied along with
XLPE insulation in a single operation by ‘triple extrusion’ process.
Method of curing is dry curing
More discussion can be downloaded.
AB cable issues and solutions , estimation, fault finding
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