AJANTA heavy duty Armoured and Unarmoured cables are manufactured with Copper / Aluminium Conductors PVC Insulated laid, up the inner sheath may be extrusion / taping process and is of thermoplastic material. The Armouring is of galvanized mild steel wire / strip. For singleE core Armoured cables intended to be used in A. C. Circuit, the Armouring is of non-ferrous metals to avoid eddy current heating and finally sheathed with higher grade PVC. The cables are manufactured under strict quality control as per IS specification No. S: 1554 (Part—1) of 1988 and are suitable for operation upto 1100 Volts.
Different colours identify the cores:
|Single core||Red, Black, Yellow, or Blue.|
|Two Core||Red & Black|
|Three Core||Red, Yellow & Blue|
|Four Core||Red, Yellow, Blue & Black|
|Five Core||Red, Yellow, Blue, Black and Grey|
|Six Core and above||Two adjacent cores, (counting and directional core)
in each layer, Blue and Yellow respectively and
remaining cores Grey
* For reduced neutral conductors, the core shall be black.
In case of Aerial Bunch Cable’s Core are identified by embossed ridges along the length, 1, 2, and 3 as phase 1, 2 and 3 respectively where as inculator is concerned.
Cables of two or more cores have a common inner sheath. The minimum thickness of inner sheath is 0.03-mm upto laid up diameter of 25 mm.
Where the calculated diameter of inner sheath doesn’t exceed 13 mm the ARMOUR is of round galvanized steel wires and for calculated diameter of inner sheath above 13 mm flat galvanized steel strips are used.
The outer is of suitable grade PVC compound in black color.
The test report with routine test, which obtained in our factory-testing laboratory, is given with every drum.
I.S.I. MARK AJANTA Heavy duty Armoured / Unarmoured cables are approved by the Indian Standard Institution and their consent is obtained to mark these cables with IS–1554.
CRITERIA FOR SELECTION OF POWER CABLES
The following factors should be taken in to account while selecting the correct size and of cables:
- SYSTEM VOLTAGE – What is the system voltage and the type of system? Single phase, Three phase, earthed or unearthed AC or DC?
- CURRENT CARRYING CAPACITY – The current rating is the main and basic criterion. Tables give the carrying capacity of various types and sizes of cables, under different conditions of laying. These should be considered before the correct size laying as under
2.1: Depth of Laying.
2.2: Ambient temperature of ground or Air.
2.3: Soil resistivity.
2.4: Whether one or more groups of the cables are laid together.
2.5: Any heating source near cable run.
- MODE OF INSTALLATION – The mode of installation determines the type of cable to be used. Electricity regulations require the use of Armoured cables for underground applications. In general, Armoured cables are recommended where there is any chance of mechanical damage. If subsequent mechanical damage after laying cables is not likely, cheaper Unarmoured cables can be used.
- PERMISSIBLE VOLTAGE DROP – For longer length of cable run it is necessary it is necessary to check that with the cable size selected, the voltage drop does not exceed the prescribed regulations limit. A higher size cable may have to be used if the voltage drop limits are not to be exceeded.
- LOAD CHARACTERISTIC – One should take into account the characteristics of load. It is essential to ensure that the cable selected is capable of handing temporary overloads. AJANTA cables permit a conductor temperatures of upto 130 ° C under temporary overload conditions. (If possible, the complete load cycle may be furnished).
- SHORT CIRCUIT RATING – Short circuit rating depends on the expected level and the expected level and the expected duration of the short circuit. In certain cases a large size of cable than the cable required for normal full load may be needed. The cables with high KVA capacity are expected to carry short circuit currents of high magnitude, “AJANTA” permit a short circuit temperature of 160 ° C.
- ECONOMIC CONSIDERATIONS – The most economical construction and size of cable persistent with current carrying capacity and laying condition has to be selected. A detailed study of 3 or 4 approximate sizes is made. Actual running costs are worked out taking into consideration I2R loss and interest, depreciation of the total cable cost. The size, which gives minimum running costs, is to be preferred.