Anandji Cables - Simplifying Electronics
NILSON - PVC Insulated Wires And Cables
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L. T. CONTROL CABLES
DESIGN SPECIFICATIONS
CURRENT RATINGS
Cables shall only be operated at their full rating if the minimum current at which circuit protection is designed to operate does not exceed 1.5 times (in case of cables in air or in ducts) or 1.3 times (in case of cables laid direct in the ground) the values tabulated in Tables I to III.

NORMAL CONDITIONS OF INSTALLATION
1 Maximum Conductor Temperature 70°C For GPPVC Insulation and
85°C For HRPVC Insulation
2 Thermal Resistivity Of Soil 150°C cm/w
3 Thermal Resistivity Of PVC 650°C cm/w
4 Ground Temperature 30° C
5 Ambient Air Temperature 40° C
6 Depth Of Laying 75 cms


SHORT CIRCUIT RATING IN K. Amp. (For One Second Duration)
Area of conductor sq. mm. Maximum Conductor Temperature
G.P. PVC H.R. PVC
1.50 sq. mm. 0.169 0.153
2.50 sq. mm. 0.283 0.255
4.00 sq. mm. 0.452 0.406
6.00 sq. mm. 0.679 0.612


FORMULA FOR CALCULATING SHORT CIRCUIT
  I1   I1 = Short Circuit Current for one seconds.
It = ---------   It = Short Circuit Current for t seconds.
  √t   t = Duration in seconds
Maximum Conductor temperature during short circuit is 160°C for both G.P. PVC & H.R. PVC Cables.


NOTE :
For cables in air no reduction in current ratings is necessary provided that:

1. The horizontal clearance between circuit is not less than six times the overall diameter of an individual cable. Not less than the overall width of individual circuit, except the horizontal clearance in any case need not exceed 150 mm.

2. The vertical clearance between circuits is not less than 150 mm.

3. If the number of circuits exceeds 4, they are installed in a horizontal plane.