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BS 7870-8.2:2003 pdf free.LV and MV polymeric insulated cab] les for use by distribution and generation utilities 一 Part 8: Specification for multicore and multipair cables for installation above and bel ow ground一 Section 8.2: Single wire armoured and PVC sheathed multipair cable with copper conductors (Implementation of part of HD 627).
The marking shall be by indenting or embossing on the oversheath.
For cables with tabulated3 approximate overall diameters greater than 15 mm, elements a). b) and c) shall appear, in any sequence that is deemed neither to confuse nor to conflict, on two or more primary lines along the axis of the cable, approximately equally spaced around the circumference of the cable. Element d) shall appear upon at least one line, which may be one of the primary lines or a secondary line.
For cables with tabulated approximate overall diameters of 15 mm or less, the elements shall be arranged as for cables of greater than 15 mm diameter, except that the marking for elements a), b) and c) shall appear on one or more primary lines.
The letters and figures shall consist of upright block characters. The characters shall have a minimum height of 3 mm.
The distance between the end of one element of marking and the beginning of the next identical element shall be not greater than 550 mm for elements a), b) and c) and not greater than 1 100 mm for element d).
Conformity shall be checked by visual examination and measurement as specified in 14.7.
11.2 Identification of year of manufacture
A means of identiMng the year of manufacture of the cable shall be provided throughout the length of the cable, either internally or by use of an identification thread or externally by marking on the surface of the cable.
If the identification is internal, the distance between the end of one mark and the beginning of the next mark shall be not greater than 550 mm.
If the identification is by marking on the external surface, the distance between the end of one element of marking and the beginning of the next identical element shall be not greater than 1100 mm.
conformity shall be checked by visual examination and measurement as specified in 14.7.
11.3 Mark of an approval organization
If the mark of an approval organization is used, it shall be provided throughout the length of the cable, either as an identification thread or by marking on the external surface of the cable, as specified by the approval organization.
If the mark is on the external surface of the cable, it shall be in the form of the symbol(s) specified by the approval organization, and the distance between the end of one element of marking and the beginning of the next identical element shall be not greater than 1100 mm.
Conformity shall be checked by visual examination and measurement as specified in 14.7.
11.4 Additional marking
Where additional marking is made, it shall be throughout the length of the cable, and on the external surface of the cable, or by means of a tape or thread within the cable, or by a combination of these methods. If the additional marking is applied to the surface of the cable, it shall not render illegible the marking specified in 11.1, 11.2 and 11.3.
The additional marking, however made, shall be repeated at intervals not exceeding 1 100 mm. Conformity shall be checked by visual examination and measurement as specified in 14.7.
12 Dimensions The dimensions of the component layers shall be as specified in Table 1, Table 2 and Table 3.
14.3 Insulation resistance
When measured in accordance with BS 7870-2:1999, 3.3.2, the insulation resistance shall be not less than the following values at 20 °C:
a) for filled cable, 5 000 MQ/km;
b) for unfilled cable, 40 000 MQ/km.
NOTE An appropriate group test procedure may be adopted to facilitate testing. The measured value should not be less than the appropriate value given in Table 5. Should the measured group insulation resistance be less than specified, then the individual cores should be tested as given above.
14.4 Voltage test
When the voltage test is carried out in accordance with BS 7870-2:1999, 3.2.1.2, using one of the following voltages for I mm, no breakdown of the insulation shall occur.
a) for induced voltage levels up to 5 kV (Table 1):
5 kV a.c. between each conductor and the remaining conductors connected to the armour and earthed;
b) for induced voltage levels up to 15 kV (Table 2):
10 kV s.c. between each conductor and the remaining conductors connected to the armour and earthed; c) for induced voltage levels above 15 kV (aluminium wire armoured) (Table 3):
15 kV a.c. or 22.5 kV d.c. between all conductors bunched and armour, which shall be earthed.
14.5 Spark test on oversheath
Spark testing of the oversheath shall be carried out in accordance with BS 7870-2:1999, 3.6.1. No failures
shall occur.
14.6 Voltage test on oversheath
When the PVC oversheath is graphite coated a d.c. voltage shall be applied between the armour and the graphite layer for 1 mm in accordance with BS 7870-2:1999. 3.2.3.1.
The oversheath shall withstand a voltage equal to 8 kV/mm of tabulated oversheath thickness in the relevant table.
14.7 Cable markings
The cable markings shall be checked by visual examination and measurement and shall conform to the requirements of Clause 11.
15 Sample tests
15.1 General
Sample tests shall be performed in accordance with the schedule of tests in Table 4 and 15.2 to 15.11.
15.2 Conductor material and construction
The conductor material and construction shall be checked by visual examination and shall conform to the requirements of Clause 4.
15.3 Insulation
The application of the insulation shall be checked by visual examination and shall conform to the requirements of Clause 5.
The thickness of the insulation shall be measured on all cores up to 5-pair, and for larger pairages, on any 10 cores.
The thickness of the insulation shall be measured using a sample that has been taken from one end of each drum length of cable selected for the test, and from which any portion that may have suffered damage has been discarded.
When this sample is measured in accordance with BS 7870-2:1999, 2.1.1, the thickness of the insulation shall conform to the value specified in Table 1, Table 2 and rCable 3. as appropriate.
If any of the thicknesses measured does not conform to the requirements specified in Table 1, Table 2 and Table 3, as appropriate, then two further samples shall be checked for the non-conforming factors. If both the further samples meet the specified requirements, the cable shall be deemed to conform, but if either does not meet the specified requirements, the cable shall be deemed not to conform.
15.4 Capacitance unbalance
When measured in accordance with IEC 60189-1:1986, 5.5. and corrected to 500 m by using the following equation, the capacitance unbalance value shall not exceed 500 pF. except for carrier pairs where the value shall not exceed 50 pF.
15.5 Pair identification
The cable cares shall be checked by visual examination and shall conform to the requirements of Clause 6.
15.6 Laid-up pairs
The laid-up pairs shall be checked by visual examination and shall conform to the requirements
of Clause 7.
15.7 Bedding layer
The thickness of the bedding layer shall be measured using a sample that has been taken from one end of each drum length of cable selected for the test, and from which any portion that may have suffered damage has been discarded.
When this sample is measured in accordance with BS 7870-2:1999, 2.1.2, the thickness of the bedding layer shall conform to the value specified in Table 1, Table 2 and rfable 3, as appropriate.
If any of the thicknesses measured does not conform to the requirements specified in Table 1, Table 2 and Table 3, as appropriate, then two further samples shall be checked for the non-conforming factors. If both the further samples meet the specified requirements, the cable shall be deemed to conform, but if either does not meet the specified requirements, the cable shall be deemed not to conform.
15.8 Armour wire
When measured in accordance with BS 7870-2:1999. 2.1.4.3a). the diameter of round armour wire shall fall within the minimum and maximum diameters specified in Table 6.BS 7870-8.2 pdf download.LV and MV polymeric insulated cab] les for use by distribution and generation utilities