power cables

Acceptance Tests
The customers can request the various acceptance tests as provided in the relevant Indian Standard to be carried out before accepting the cables.

Type Tests
These tests are carried out on samples taken from each production lot. They are carried out to prove conformity as regards the general qualities and design to the specification of particular type of cable. These tests are enumerated in the relevant Indian Standards.

Routine Tests
The following tests constitute Routine Tests, which are carried out on each and every length of cable before it leaves the factory:

Testing of PVC Cables
Testing is a vital part of cable manufacturing and all raw materials and finished cables are thoroughly tested to ensure quality control. Rallison has a well equipped testing laboratory for carrying out electrical, mechanical and chemical tests which are required as per relevant specifications. The various tests as provided in the Indian Standards are carried out on Rallison Cables. These are classified in three different groups:

Type Designation
The following code is used for designating the type of cable:

Outer Sheath
Over the armouring, or in case of unarmoured cables, over the inner sheath (for single core cables over the insulation), a tough outer sheath of PVC is applied by extrusion. This is normally Black in colour. This provides a tough but smooth outer covering to PVC Cables. The trademark "Rallison" along with the year/code of manufactured are embossed on the outer sheath. Wherever desired the customer name can also be embossed on the cable. The embossing script repeats at desired length of cable.

Armouring of PVC Mining Cables consist of Galvanised Round Steel Wires/Strips, but wherever necessary, a few Tinned Copper Wires/Strips are also included to meet the resistance requirements of armouring for Mining Cables.

Armouring
Depending upon the application, the cables can be armoured. The armouring can be Round Steel Wire or Steel Strips. In case of cables where diameter over the inner sheath does not exceed 13 mm, the armour consists of Galvanished Round Steel Wires; above this size, the armour can be Galvanished Flat Steel Strips or Galvanished Round Steel Wires as per customers' requirement. In case of single core cables intended for use of an A.C. Systems, the armouring shall be of Aluminium Wires/Stripes or any other non-magnetic material.

Inner Sheath
For all cables having two or more cores, a common covering (inner sheath) is provided over the laid up cores either by extrusion or by wrapping of plastic or proofed tapes. Single core cables do not require inner sheath.

The following colour scheme is adopted.

Core Identification & Colour Scheme
Cores are identified by colour scheme of PVC insulation.

Insulation
The conductors are insulated with suitably compounded PVC, which is applied to the conductor by extrusion process.

Conductor
The conductor shall be composed of plain copper or aluminum wires complying with IS: 8130-1984. Mining Cables to be used in gassy mines shall be of copper conductor only.

General Construction of PVC Cables

PVC rapidly replaced rubber for wiring cables shortly after 1945 and for Power cables insulation in late 1950s in Europe. In India, the PVC power & Control Cables came into operation in early 1960s. The use of PVC provided cables of excellent quality which were clean and much easier to handle. Further, simplified terminators and jointing techniques make these cables eminently suitable among other applications for Industrial and Mining installation. The main advantages of PVC Cables can thus be summarized as under: