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(') Clause numbers refer to this section unless stated otherwise.SECTION D : CABLES WITH COPPER AND ALUMINIUM CONDUCTORS;
UNARMOURED, ARMOURED OR DOUBLE-SCREENED

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2.4.4 Test related to fire conditions Reduced flame propagation

All cables shall comply with the test specified in pr HD 405-3 Category C.

3. Cables without metallic layers:

Cross linked polyethylene insulated, and polyvinyl chloride sheathed cable

(under consideration by TC20)

YMvK mb

0.6/1 kV

Number of conductors 1, 2, 3, 4 or 5 and for the cross-sections 1.5 and 2.5 mm² up to and including 61. Conductors of three and four core cables with a cross-sectional area of 35mm² and above may be circular or shaped.

Conductors shall comply with the requirements of HD 383. For each size of cable the class of conductor is given in Tables III or IV.

A separator of suitable material may be applied around each conductor. If required, tapes may be applied to comply with fire resistant requirements.

The insulation shall be XLPE compound complying with the non-electrical requirements given in Table I. The insulation thickness shall comply with the value specified in Tables III or IV.

The cores shall be twisted together. For an assembly of cores consisting of 2 or more layers, the direction of lay shall alternate for each successive layer.

The twisted cores shall be covered by an extruded inner covering consisting of an unvulcanised rubber or plastic compound. For cables with shaped conductors and cables with more than five cores, the extruded inner covering may be replaced by a non-hygroscopic tape wrapping.

It shall be possible to separate the cores easily.

The sheath shall be polyvinyl chloride compound of Type PVC/ST complying with the non-electrical requirements given in Table I. The sheaths shall be applied around the inner covering or tape wrapping. It shall fit closely on the inner covering.

The sheath thickness for cables with a number of cores not exceeding five shall comply with the specified value given in Tables III or IV. For cables with more than five cores the specified value for the thickness of the sheath is 1.8mm for cables with a number of cores up to and including 40 and 2.1mm for cables with more than 40 cores.

For cables with a number of cores not exceeding five and with circular solid or circular stranded non-compacted conductors, the mean overall diameter shall be within the limits given in Table III. For other cables no limits for the mean overall diameter are prescribed.

Cables shall be marked continuously with the letters mb in compliance with 3.1 Item 2c).

Compliance with the requirements of Sub-clause 3.3 and the appropriate requirements of Part 1 shall be checked by inspection and by the tests specified in Table ll-A.

3. Cables with metallic layers

   1. Armoured cables: Cross linked polyethylene insulated and polyvinyl chloride sheathed cable with combined armour/protective earth conductor,

      1. Code designation (Provisional)

(Under consideration by TC20)

VO-YMvKas mb for cables with a braided armour/protective earth conductor VG-YMvKas mb for cables with a helically applied armour/protective earth conductor.

0.6/1 kV

Number of conductors 1,2, 3, 4 or 5 and for the cross-sections 1.5 and 2.5mm² up to and including 61. Conductors of three and four core cables with a cross-sectional area of 35 mm² and above may be circular or shaped.

Conductors shall comply with the requirements of HD 383. For each size of cable the class of conductor is given in Tables V and VI.

The insulation shall be XLPE compound complying with the non-electrical requirements given in Table I. The insulation thickness shall comply with the value specified in Tables V and VI.

The cores of multicore cables shall be twisted together. For an assembly of cores consisting of 2 or more layers, the direction of lay shall alternate for each successive layer.

The twisted cores shall be covered by an extruded inner covering consisting of an unvulcanised rubber or plastic compound. For cables with shaped conductors and cables with more than five cores, the extruded inner covering may be replaced by a non-hygroscopic tape wrapping.

It shall be possible to separate the cores easily.

The inner sheath shall be polyvinyl chloride compound of Type PVC/ST complying with the non-electrical requirements given in Table I. The sheath shall be applied around the inner covering or tape wrapping. It shall fit closely on the inner covering.

The inner sheath thickness for cables with a number of cores not exceeding five shall comply with the specified value given in Tables V or VI. For cables with more than five cores the specified value for the thickness of the inner sheath is 0.8mm.

4 1.3.7 Combined armour/protective earth (PE) conductor

The armour/PE conductor shall be applied around the inner sheath as a braid or in helical form.

The armour/PE conductor shall comply with the following requirements.

4.1.3.7.1 Composition

The armour/PE conductor shall consist of:

• a braid of galvanised steel wires or plain or tinned copper wires with a continuous flat braided conductor of tinned copper wires underneath,

or

• an assembly of round or flat galvanised steel and plain or tinned copper wires, surrounded by a counter-helix of galvanised steel tape or plain or tinned copper tape, or

• an assembly of round or flat, plain ortinned, copperwires surrounded by a counter-helix of plain or tinned copper tape.

The armour/PE conductor may be covered by a separator f non-hygroscopic material.

The thickness of the elements shall not be less than the specified value for each type and size of cable shown in Tables V, VI and VII as appropriate.

The connection of the armour/PE conductor other than a complete copper armour, to earth shall be possible by means of one or more continuous copper conductors in contact with or forming part of the armour/PE conductor.

The cross-sectional area of the braided conductor or of each of the latter copper conductors shall be at least 1mm² and the total cross-sectional area shall not be less than 60%, with a minimum of 1.5mm², of the nominal copper equivalent cross-sectional area of the armour/PE conductor which is specified in Tables V, VI and VII as appropriate; the electrical resistance however being the criterion.

The surface of the inner sheath shall be covered by the armour/PE conductor for at least 80% and the gap between the elements shall not exceed 2mm.

Compliance with the above specified requirements shall be checked by inspection and measurement. For the percentage of coverage of a braided armour/PE conductor the calculation method is given in sub-clause 2.1.7 of HD 605.

The electrical resistance of the combined armour/PE conductor shall not exceed the specified value for each type and size of cable shown in the Table V, VI and VIII as appropriate.

Additionally, the resistance of the armour/PE conductor measured on a length of 20m with the current source at one side connected to 5% of the number of elements of the braided armour or two adjacent steel wires of the helically applied armour shall not exceed 2.5% of the specified maximum value per km. Compliance shall be checked by the test given in sub-clause 3.1.3.1 and 3.1.3.2 respectively of HD 605.

There shall be no harmful interactions between the armour/PE conductor and the inner sheath or oversheath. Inspection after the test given in HD 505.1.2, sub-clause 8.1.4 shall show no impairment of the armour/PE conductor.

The following ageing conditions apply: - temperature : (100 ± 2)°С

- duration : 7 x 24h

The separator, if any, shall consist of a plastic tape or an equivalent layer around the armour/PE conductor.

The oversheath shall be polyvinyl chloride compound of Type PVC/ST complying with the non-electrical requirements given in Table I. The oversheath shall be applied around the armour/PE conductor, or a tape if any.

The thickness of the oversheath for cables with a number of cores not exceeding five, shall comply with the specified value given in Tables V or VI. For cables with more than five cores the specified value for the thickness of the oversheath is 1.8mm for cables with a number of cores up to and including 40 and 2.1 mm for cables with more than 40 cores.

For cables with an armour/PE conductor no limits for the mean overall diameter are prescribed.

Cables shall be marked continuously with the letters mb in compliance with 3.1 Item 2c).

4.1.4 Tests

Compliance with the requirements of sub-clause 4.1.3 and the appropriate requirements of Part 1 shall be checked by inspection and by the tests specified in Table ll-A.

4.2 Screened cables: Double screened, cross linked polyethylene insulated and polyvinyl chloride sheathed cable

(Under consideration by TC20)

YMvKafas mb for single core cables

V-YMvKafas mb for multicore cables

0.6/1 kV

Number of copper conductors 1, 3 or 5.

Conductors shall comply with the requirements of HD 383. For each size of cable the class of conductor is given in Table VIII

A separator of suitable material may be applied around each conductor. If required, tapes may be applied to comply with fire resistant requirements.

The insulation shall be XLPE compound complying with the non-electrical requirements given in Table I. The insulation thickness shall comply with the value specified in Tables VIII.

The core of single core cable shall be coloured green/yellow. For three and five core cables the core with the largest cross-sectional area shall be coloured green/yellow.

The cores of multicore cables shall be twisted together. A centre filler may be used.

The twisted cores shall be covered by an extruded inner covering consisting of an unvulcanised rubber or plastic compound. It shall be possible to separate the cores easily.

The sheath shall be polyvinyl chloride compound of Type PVC/ST complying with the non-electrical requirements given in Table I. It shall fit closely on the inner covering.

The sheath thickness shall comply with the specified values given in Table VIII.

The screen shall be composed as follows:

• a symmetrical galvanised steel wire braid;

• a separator of non-hygroscopic material (e.g a tape or an extruded layer);

• a symmetrical plain or tinned copper wire braid.

The screen shall be applied around the insulation of single core cables and around the inner sheath of multicore cables.

The screen may be covered by a separator of non-hygroscopic material.

The nominal diameter of the wires of the braid shall not be less than the specified value for each size of cable shown in Table Vlil.

However, each value measured shall not be less than 90% of the nominal value plus 0.03mm nor be more than 110% of the nominal value plus 0.03mm.

Compliance with the above mentioned requirements shall be checked by inspection and measurement.

The electrical resistance of the copper braid shall not exceed the specified value for each size of cable shown in Table VIII. Compliance shall be checked by the test given in sub-clause 3.1.4.1 of HD 605.

The transfer impedance at the frequency of 30 MHz shall not exceed 10 ohm/km.

Compliance shall be checked by the test given in IEC 96-1, Sub-clause A.5.1 and A.5.2.

The separator, if any, shall consist of a plastic tape or an equivalent layer around the screen.

The (over)sheath shall be polyvinyl chloride compound of Type PVC/ST complying with the non-electrical requirements given in Table I. The sheath and oversheath shall be applied around the screen or separator, if any, of respectively single core and multicore cables.

It shall fit closely but not adhere to the screen. The thickness of the (over) sheath shall comply with the specified value given in Table VIII.

For screened cables no limits for the mean overall diameter are prescribed.

Cables shall be marked continuously with the letters mb in compliance with 3.1 item 2 c).

Compliance with the requirements of sub-clause 4.2.3 and the appropriate requirements of Part 1 shall be checked by inspection and by the tests specified in Table ll-B.

Table I • Requirements for the non-electrical test for cross-linked polyethylene
insulation and polyvinyl chloride sheath

T

difference between the median value after ageing and the median value without ageing, expressed as a percentage of the latter.

able I (continued) - Requirements for the non-electrical test for cross-linked polyethylene