طريقة حساب سمك طبقات القابلو

Fictitious Calculation method a. 4x4 mm2 CU/XLPE/SWA/PVC 0.6/1 kV 1. Conductor (4 mm2): Fictitious diameter of conductor dL = 2.3 mm 2. Cores: The fictitious diameter Dc of any core is given by: Dc = dL + 2ti Where ti is the nominal thickness of insulation, ti = 0.7 mm Therefore, Dc = 2.3 + 2*0.7 = 3.7 mm 3. Diameter over laid-up cores The fictitious diameter over laid-up cores (Df) is given by: Df = k Dc Where the assembly coefficient k is 2.42 for a four-cores cable Therefore, Df = 2.42 * 3.7 = 9.0 mm 4. Thickness of extruded inner covering As per table 8.0 of IEC 60502-1, if the fictitious diameter over laid-up cores above - mm up to and including 25 mm, the nominal thickness of extruded inner covering is 1.0 mm.

5. Inner Coverings The fictitious diameter over the inner covering (DB) is given by: DB = Df + 2 tB Where tB = 0.4 mm for fictitious diameter over laid-up cores (Df ) up to and including 40 mm DB = 9.0 + 2 * 0.4 = 9.8 mm 6. Armour The nominal diameters of round armour wires shall be as per table 9.0 of IEC 60502-1. As per table 9.0 of IEC 60502-1, if the fictitious diameter under the armour above - mm up to and including 10 mm, the nominal diameter of round armour wires shall be 0.8 mm.

b. 4x4 mm2 CU/XLPE/LEAD/SWA/PVC 0.6/1 kV Page 1/3

1. Conductor (4 mm2): Fictitious diameter of conductor dL = 2.3 mm 2. Cores: The fictitious diameter Dc of any core is given by: Dc = dL + 2ti Where ti is the nominal thickness of insulation, ti = 0.7 mm Therefore, Dc = 2.3 + 2*0.7 = 3.7 mm 3. Diameter over laid-up cores The fictitious diameter over laid-up cores (Df) is given by: Df = k Dc Where the assembly coefficient k is 2.42 for a four-cores cable Therefore, Df = 2.42 * 3.7 = 9.0 mm 4. Thickness of extruded inner covering As per table 8.0 of IEC 60502-1, if the fictitious diameter over laid-up cores above - mm up to and including 25 mm, the nominal thickness of extruded inner covering is 1.0 mm.

5. Inner Coverings The fictitious diameter over the inner covering (DB) is given by: DB = Df + 2 tB Where tB = 0.4 mm for fictitious diameter over laid-up cores (Df ) up to and including 40 mm DB = 9.0 + 2 * 0.4 = 9.8 mm 6. Lead sheath The fictitious diameter over the lead sheath (Dpb) is given by: Dpb = Dg + 2 tpb Where Dpb is the fictitious diameter under the lead sheath in millimetres; tpb is the thickness calculated in accordance with clause 11, in millimetres; As per clause 11, tpb = 0.03 Dg + 0.7 = 1. 0 mm But, the as per clause 11, the smallest nominal thickness of lead sheath shall not be less than 1.2 mm.

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Therefore, the fictitious diameter over the lead sheath (Dpb) is given by: Dpb = Dg + 2 tpb = 9.8 + 2 * 1.2 = 12.2 mm 7. Separation sheath The fictitious diameter over the separation sheath (Ds) is given by: Ds = Du + 2 ts Where Du is the fictitious diameter under the separation sheath in millimetres; ts is the thickness calculated in accordance with clause 12.3.3, in millimetres; As per clause 12.3.3, tpb = 0.02 Du + 0.6 = 0.02 * 12.2 + 0.6 = 0.8 mm But, as per clause 12.3.3, the nominal thickness of the separation sheath shall not be less than 1.0 mm where applied directly over the lead sheath.

Therefore, the fictitious diameter over the separation sheath (Ds) is given by: Ds = Du + 2 ts = 12.2 + 2 *1.0 = 14.2 8. Armour The nominal diameters of round armour wires shall be as per table 9.0 of IEC 60502-1. As per table 9.0 of IEC 60502-1, if the fictitious diameter under the armour above 10 mm up to and including 15 mm, the nominal diameter of round armour wires shall be 1.25 mm.

Note that as per IEC 60502-1 all the value shall be rounded to 0.1 mm

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