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Cable Tray should be perforated and 20% spare Capacity. Distance between each Cable is 10mm. Cable are laying in Single Layer in Cable Tray.
(1) 2 No’s of 3.5Cx300 Sq.mm XLPE Cable having 59.7mm Outer Diameter and 5.9 Kg/Meter weight
(2) 2 No’s of 3.5Cx400 Sq.mm XLPE Cable having 68.6mm Outer Diameter and 6.1 Kg/Meter weight
(3) 3 No’s of 3.5Cx25 Sq.mm XLPE Cable having 25mm Outer Diameter and 0.5 Kg/Meter weight
Total Outer Diameter of all Cable Passing in to Cable Tray:
Diameter of 300Sq.mm Cable =No of Cable X Outer Diameter of Each Cable
Diameter of 300Sq.mm Cable =2X59.7 = 119.4 mm
Diameter of 400Sq.mm Cable =No of Cable X Outer Diameter of Each Cable
Diameter of 400Sq.mm Cable =2X68.6= 137.2 mm
Diameter of 25Sq.mm Cable =No of Cable X Outer Diameter of Each Cable
Diameter of 25Sq.mm Cable =3X28= 84 mm
Total Diameter of All Cables laying in Tray = (119.4+137.2+54)mm
Total Diameter of All Cables laying in Tray = 340.6mm
Total Weight of Cables Passing in to Cable Tray:
Weight of 300Sq.mm Cable =No of Cable X Weight of Each Cable
Weight of 300Sq.mm Cable =2X5.9= 11.8 Kg/Meter
Weight of 400Sq.mm Cable = No of Cable X Weight of Each Cable
Weight of 400Sq.mm Cable =2X6.1= 12.2 Kg/Meter
Weight of 25Sq.mm Cable = No of Cable X Weight of Each Cable
Weight of 25Sq.mm Cable =3X0.5= 1.5 Kg/Meter
Total Weight of All Cables laying in Tray = (11.8+12.2+1.5) Kg/Meter
Total Weight of All Cables laying in Tray =25.5 Kg/Meter
Total Width of all Cables:
Total Width of all Cables = (Total No of Cable X Distance between Each Cable) + Total Cable Outer Diameter
Total Width of all Cables = (7 X 10) + 340.6
Total Width of all Cables = 410.6 mm
Taking 20% Spare Capacity of Cable Tray
Final Width of all Cables = 1.2%X4106.6
Calculated Width of All Cables = 493 mm
Total Area of Cable:
Total Area of Cable = Final width of Cables X Maximum Height Cable
Total Area of Cable = 493 X 69.6 =28167 Sq.mm
Taking 20% Spare Capacity of Cable Tray
Final Area of all Cables = 1.2%X28167
Calculated Area of all Cable =33801 Sq.mm
CASE-(I):
Considering Single Run of Cable Tray having Size of 300X100mm, 120Kg/Meter Weight Capacity
Area of Cable Tray =Width of Cable Tray X Height of Cable Tray
Area of Cable Tray =300X100 = 30000 Sq.mm
Checking Width of Cable Tray
Calculated Width of Cable Tray as per Calculation=No of Layer of Cable X No of Cable Tray Run X Width of Cables
Width of Cable Tray as per Calculation=1X1X493 =493 mm
Checking Depth of Cable Tray
Actual depth of Cable Tray = No of Layer of Cable X Maximum Diameter of Cable
Actual depth of Cable Tray=1X68.6 =68.6mm
Checking Weight of Cable Tray
Actual Weight of Cables=25.5 Kg/Meter
Results:
Calculated Cable Tray width (493mm)> Actual Cable Tray width ( 300mm) = Faulty Selection
Calculated depth of Cable Tray (68.6mm)< Actual Depth of Cable Tray (100mm) = O.K
Calculated Weight of all Cables (25.5Kg/Mt) < Actual Weight of Cable Tray (125.5 Kg/Mt) =O.K
Required to select higher size Cable Tray due to small Cable Tray width.
CASE-(II):
Considering Single Run of Cable Tray having Size of 600X100mm, 120Kg/Meter Weight Capacity
Area of Cable Tray =Width of Cable Tray X Height of Cable Tray
Area of Cable Tray =600X100 = 60000 Sq.mm
Checking Width of Cable Tray
Width of Cable Tray as per Calculation=No of Layer of Cable X No of Cable Tray Run X Width of Cables
Width of Cable Tray as per Calculation=1X1X493 =493 mm
Checking Depth of Cable Tray
Actual depth of Cable Tray = No of Layer of Cable X Maximum Diameter of Cable
Actual depth of Cable Tray=1X68.6 =68.6mm
Checking Weight of Cable Tray
Actual Weight of Cables=25.5 Kg/Meter
Results:
Calculated Cable Tray width (493mm)< Actual Cable Tray width ( 600mm) = O.K
Calculated depth of Cable Tray (68.6mm)< Actual Depth of Cable Tray (100mm) = O.K
Calculated Weight of all Cables (25.5Kg/Mt) < Actual Weight of Cable Tray (125.5 Kg/Mt) =O.K
Remaining Cable Tray width Area =100%-(Calculated Cable tray width/ Actual Cable Tray Width)
Remaining Cable Tray width Area =100%-(493/600)% =17.9%
Remaining Cable Tray Area =100%-(Calculated Cable tray Area/ Actual Cable Tray Area)
Remaining Cable Tray Area =100%-(33801/60000) =43.7%
Selection of 600X100 Cable Tray is O.K
The question is too vague but I could give you some ideas on how to design a cable tray. You must determine the the numbers and size of cables that will pass to that particular tray for you to determine dimensions of cable tray you are going to use.
