IEC 60227-7-2003 pdf – Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V – Part 7: Flexible cables screened and unscreened with two or more conductors.
1 General 1.1 Scope This part of IEC 60227 details the particular specifications for polyvinyl chloride insulated, screened and unscreened control cables of rated voltages up to and including 300/500 V. All cables comply with the appropriate requirements given in IEC 60227-1 and each individual type of cable complies with the particular requirements of this part. 1.2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. IEC 60096-1:1986, Radio-frequency cables – Part 1: General requirements and measuring methods IEC 60227-1:1993, Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V – Part 1: General requirements IEC 60227-2:1979, Polyvinyl chloride insulated cables of rated voltages up to and including 450/750 V – Part 2: Test methods IEC 60228:1978, Conductors of insulated cables IEC 60332-1:1993, Tests on electric cables under fire conditions – Part 1: Test on a single vertical insulated wire or cable IEC 60502-1:1997, Power cables with extruded insulation and their accessories for rated voltages from 1 kV (U m = 1,2 kV) up to 30 kV (U m = 36 kV) – Part 1: Cables for rated voltages of 1 kV (U m = 1,2 kV) and 3 kV (U m = 3,6 kV) IEC 60719:1992, Calculation of the upper and lower limits for the average outer dimensions of cables with circular copper conductors and of rated voltages up to and including 450/750 V IEC 60811-1-1:1993, Common test methods for insulating and sheathing materials of electric cables – Part 1: Methods for general applications – Section 1: Measurement of thickness and overall dimensions – Tests for determining the mechanical properties IEC 60811-1-2:1985, Common test methods for insulating and sheathing materials of electric cables – Part 1: Methods for general applications – Section 2: Thermal ageing methods
IEC 60811-1-4:1985, Common test methods for insulating and sheathing materials of electric cables – Part 1: Methods for general applications – Section 4: Tests at low temperature IEC 60811-2-1:1986, Common test methods for insulating and sheathing materials of electric cables – Part 2: Methods specific to elastomeric compounds – Section 1: Ozone resistance test – Hot set test – Mineral oil immersion test IEC 60811-3-1:1985, Common test methods for insulating and sheathing materials of electric cables – Part 3: Methods specific to PVC compounds – Section 1: Pressure test at high temperature – Tests for resistance to cracking IEC 60811-3-2:1985, Common test methods for insulating and sheathing materials of electric cables – Part 3: Methods specific to PVC compounds – Section 2: Loss of mass test – Thermal stability test 2 Oil resistant, polyvinyl chloride sheathed, screened and unscreened flexible cable 2.1 Code designation 60227 IEC 74 for screened cable 60227 IEC 75 for unscreened cable 2.2 Rated voltage 300/500 V 2.3 Construction 2.3.1 Conductor Number conductors: 2 to 60. Preferred number of conductors: 2, 3, 4, 5, 6, 7, 12, 18, 27, 36, 48 and 60. The conductors shall comply with the requirements given in IEC 60228 for class 5 conductors 2.3.2 Insulation The insulation shall be polyvinyl chloride compound of type PVC/D (see IEC 60227-1) applied around each conductor. The insulation thickness shall comply with the specified value given in column 2 of table 1 or 2. The insulation resistance shall be not less that the value given in table 1, column 8 or table 2, column 6. 2.3.3 Assembly of cores and fillers, if any The cores shall be twisted together, where appropriate in several concentric layers. A centre core is not permitted but a centre filler of suitable material shall be applied for cables with five or more cores in the first layer. Assemblies with three or more cores shall have one core which is coloured green and yellow.
Around each layer a tape may be applied which may cover the cores fully or partially. The tape shall not adhere to the cores. For two-core cables, the space between the cores shall be filled either by separate fillers or by the sheath filling the interstices. 2.3.4 Inner sheath for screened cables The inner sheath shall be a polyvinyl chloride compound of type PVC/ST5 (see IEC 60227-1) applied around the core assembly. For all cables, the thickness of the inner sheath shall be determined by the formula: t is = 0,02 D f + 0,6 mm, where D f is the fictitious diameter over the laid-up core, calculated in accordance with A.2.1, A.2.2 and A.2.3 of IEC 60502, annex A, and where the fictitious diameter (d l ) of 0,5 mm 2 , 0,75 mm 2 and 1,0 mm 2 conductors (not given in A.2.1) shall be taken to be 0,8 mm, 1,0 mm and 1,1 mm, respectively. For cables with the preferred number of cores, the calculated values of the inner sheath thickness are given in column 3 of table 1. NOTE In the case of cables comprising 10 or more cores, the values specified apply to a core assembly in two or more layers. The mean value of the thickness of the sheath shall be not less that the calculated value. However, the thickness at any place may be less than the calculated value provided that the difference does not exceed 0,1 mm + 15 % of the calculated value. The inner sheath may fill the interstices of the laid-up core assemby, but it shall not adhere to the cores.