NA2XSBY - YJLV62 - Single Core

MEDIUM VOLTAGE CABLE

NA2XSBY – YJLV62 (AL/XLPE/CTS/STA/PVC) IEC 60502-2

NA2XSBY – YJLV62 is a single-core armoured medium voltage cable with a compacted aluminium conductor, XLPE insulation, a copper tape screen, non-magnetic steel tape armour (STA) and a PVC outer sheath, built in accordance with IEC 60502-2 for 3.6/6 (7.2) kV to 18/30 (36) kV. In the German-style code, 2X denotes XLPE insulation, S the copper screen and Y the PVC sheath, while A indicates the aluminium conductor; YJLV62 is the Chinese type code. It takes external mechanical force but not heavy pulling loads.

NA2XSBY – YJLV62 has one screened core per cable with an armour layer for mechanical protection. Two extruded semi-conducting layers confine the electrical field within the XLPE insulation, and a copper tape screen forms the earthed metallic layer. A PVC separation sheath keeps the copper screen apart from the steel tape armour. On AC systems, IEC 60502-2 requires the armour of single-core cables to be non-magnetic unless a special construction is chosen. The XLPE insulation allows 90 °C in normal operation and 250 °C during a short circuit.

Cable Construction

  • Conductor: Aluminium, Class 2 stranded and compacted circular, as defined in IEC 60228; the standard permits measures for longitudinal watertightness in Class 2 conductors (IEC 60502-2 Clause 5).
  • Conductor screen: Extruded semi-conducting compound applied over the conductor (IEC 60502-2 Clauses 7.1 and 7.2).
  • Insulation: Extruded XLPE, with nominal thickness selected by rated voltage and cross-section from IEC 60502-2 Table 6; the thickness of the semi-conducting screens is not included (IEC 60502-2 Clause 6.2).
  • Insulation screen: Semi-conducting compound extruded directly onto the insulation, of either the bonded or the strippable type (IEC 60502-2 Clause 7.3).
  • Metallic screen: Copper tape over the insulation screen; being non-magnetic, it meets the requirement for single-core cables; dimensions to national regulations and/or standards (IEC 60502-2 Clauses 9, 10.1 and 10.2).
  • Separation sheath: Extruded PVC sheath between the copper screen and the armour, required because the two metal layers are of different materials (IEC 60502-2 Clause 13.3.3).
  • Armour: Two helical layers of non-magnetic steel tape, the outer tape centred over the gap of the inner tape and the gap between turns not more than 50% of the tape width; nominal thickness not less than Table 10 for the diameter under the armour (IEC 60502-2 Clauses 13.2, 13.5 and 13.7).
  • Outer sheath: Extruded PVC compound type ST2, the PVC grade rated for 90 °C (Table 4), black as standard; nominal thickness 0.035D + 1.0 mm and not less than 1.4 mm for single-core cables (IEC 60502-2 Clauses 14.1 to 14.3).

Rated Voltages and Insulation

Rated Voltage U0/U (Um) Nominal XLPE Insulation Thickness Cross-Sections in TDS
3.6/6 (7.2) kV 2.5 mm up to 185 mm², rising to 3.2 mm at 500 mm² and 630 mm² 1×25 mm² to 1×630 mm²
6/10 (12) kV 3.4 mm 1×25 mm² to 1×630 mm²
8.7/15 (17.5) kV 4.5 mm 1×25 mm² to 1×630 mm²
12/20 (24) kV 5.5 mm 1×35 mm² to 1×630 mm²
18/30 (36) kV 8.0 mm 1×50 mm² to 1×630 mm²

Choose the U0 rating from both the system voltage and the way the system clears earth faults. IEC 60502-2 Table 1 groups systems into Categories A, B and C; on a 17.5 kV system, for instance, 8.7/15 kV cable serves Categories A and B, whereas Category C calls for 12/20 kV cable. Overall diameters and weights in the TDS tab are approximate values that vary with the metallic screen and armour specified; insulation, armour and sheath dimensions are nominal values.

Typical Applications

  • Medium voltage distribution networks
  • Indoor, tunnel, cable trench and underground routes where the cable meets external mechanical force but no heavy pulling
  • Transformer substations and power stations
  • Industrial plants

NA2XSBY – YJLV62 is a screened single-core armoured medium voltage cable with aluminium conductor, XLPE insulation, copper tape screen, non-magnetic steel tape armour (STA) and PVC oversheath, built to IEC 60502-2. The characteristics below follow the voltage, material, thickness and temperature requirements of that standard; per-size dimensions, weights and conductor resistances are given in the TDS tab.

Technical Characteristics

Applicable Standard IEC 60502-2
Standard Scope Extruded-insulation power cables for fixed installations at rated voltages from 6 kV (Um = 7.2 kV) up to 30 kV (Um = 36 kV)
Rated Voltage U0/U (Um) 3.6/6 (7.2), 6/10 (12), 8.7/15 (17.5), 12/20 (24) and 18/30 (36) kV
Number of Cores 1
Conductor Aluminium, Class 2 compacted circular to IEC 60228
Nominal Cross-Section Range 25 mm² to 630 mm²; smallest size depends on rated voltage
Conductor Resistance at 20 °C Not exceeding the IEC 60228 maximum; TDS values follow IEC 60228 Table 2
Conductor and Insulation Screens Extruded semi-conducting compound
Insulation XLPE, nominal thickness to IEC 60502-2 Table 6
Metallic Screen Copper tape
Separation Sheath Extruded PVC between copper screen and armour
Armour Double non-magnetic steel tape, nominal thickness not less than IEC 60502-2 Table 10
Outer Sheath PVC (type ST2), black as standard; nominal thickness 0.035D + 1.0 mm, minimum 1.4 mm
Maximum Conductor Temperature, Normal Operation 90 °C
Maximum Conductor Temperature, Short Circuit 250 °C, for a duration of not more than 5 s
Installation Indoors, tunnels, cable trenches and underground; not for heavy pulling loads

Ordering Information

Please state the rated voltage U0/U (Um), the nominal conductor cross-section, the required metallic screen cross-section or short-circuit rating, the total length and length per drum, the sheath colour if other than black and whether a strippable insulation screen is required.

No. of Cores and Nominal Cross Section Nominal Insulation Thickness Nominal Steel Tape Thickness Nominal Sheath Thickness Approx. Overall Diameter Approx. Weight Max. D.C. Resistance of Conductor at 20°C
mm² mm mm mm mm kg/km Ω/km
3.6/6(7.2)kV
1×25 2.5 0.20 1.6 20.2 576 1.20
1×35 2.5 0.20 1.6 21.2 638 0.868
1×50 2.5 0.20 1.7 22.5 720 0.641
1×70 2.5 0.20 1.7 24.2 837 0.443
1×95 2.5 0.20 1.8 26.2 985 0.320
1×120 2.5 0.20 1.8 27.4 1093 0.253
1×150 2.5 0.20 1.9 29.1 1233 0.206
1×185 2.5 0.20 1.9 30.8 1394 0.164
1×240 2.6 0.20 2.0 33.5 1663 0.125
1×300 2.8 0.50 2.2 37.7 2322 0.100
1×400 3.0 0.50 2.3 41.0 2740 0.0778
1×500 3.2 0.50 2.4 45.2 3283 0.0605
1×630 3.2 0.50 2.5 49.3 3909 0.0469
6/10(12)kV
1×25 3.4 0.20 1.7 22.4 678 1.20
1×35 3.4 0.20 1.7 23.4 743 0.868
1×50 3.4 0.20 1.8 24.7 830 0.641
1×70 3.4 0.20 1.8 26.4 954 0.443
1×95 3.4 0.20 1.9 28.4 1108 0.320
1×120 3.4 0.20 1.9 29.6 1221 0.253
1×150 3.4 0.20 2.0 31.3 1366 0.206
1×185 3.4 0.20 2.0 33.0 1534 0.164
1×240 3.4 0.50 2.1 36.7 2141 0.125
1×300 3.4 0.50 2.2 39.1 2437 0.100
1×400 3.4 0.50 2.3 42.2 2845 0.0778
1×500 3.4 0.50 2.4 45.8 3341 0.0605
1×630 3.4 0.50 2.5 49.9 3970 0.0469
8.7/15(17.5)kV
1×25 4.5 0.20 1.7 24.8 798 1.20
1×35 4.5 0.20 1.8 26.0 879 0.868
1×50 4.5 0.20 1.8 27.1 959 0.641
1×70 4.5 0.20 1.9 29.0 1102 0.443
1×95 4.5 0.20 1.9 30.8 1251 0.320
1×120 4.5 0.20 2.0 32.2 1382 0.253
1×150 4.5 0.20 2.0 33.7 1520 0.206
1×185 4.5 0.50 2.1 36.8 2053 0.164
1×240 4.5 0.50 2.2 39.3 2352 0.125
1×300 4.5 0.50 2.3 41.7 2658 0.100
1×400 4.5 0.50 2.4 44.8 3079 0.0778
1×500 4.5 0.50 2.5 48.6 3616 0.0605
1×630 4.5 0.50 2.6 52.5 4237 0.0469
12/20(24)kV
1×35 5.5 0.20 1.9 28.4 1013 0.868
1×50 5.5 0.20 1.9 29.5 1097 0.641
1×70 5.5 0.20 2.0 31.4 1247 0.443
1×95 5.5 0.20 2.0 33.2 1403 0.320
1×120 5.5 0.20 2.1 34.6 1540 0.253
1×150 5.5 0.50 2.1 37.3 2032 0.206
1×185 5.5 0.50 2.2 39.2 2247 0.164
1×240 5.5 0.50 2.3 41.7 2556 0.125
1×300 5.5 0.50 2.4 44.3 2889 0.100
1×400 5.5 0.50 2.5 47.2 3304 0.0778
1×500 5.5 0.50 2.6 51.0 3857 0.0605
1×630 5.5 0.50 2.7 55.1 4523 0.0469
18/30(36)kV
1×50 8.0 0.20 2.1 34.9 1439 0.641
1×70 8.0 0.50 2.2 38.0 1960 0.443
1×95 8.0 0.50 2.2 39.8 2149 0.320
1×120 8.0 0.50 2.3 41.2 2311 0.253
1×150 8.0 0.50 2.3 42.9 2500 0.206
1×185 8.0 0.50 2.4 44.8 2732 0.164
1×240 8.0 0.50 2.5 47.3 3063 0.125
1×300 8.0 0.50 2.5 49.7 3405 0.100
1×400 8.0 0.50 2.6 52.6 3844 0.0778
1×500 8.0 0.50 2.7 56.4 4431 0.0605
1×630 8.0 0.50 2.9 60.7 5159 0.0469

Electrical Tests

  • In accordance with IEC 60502-2 Clause 16.2, the d.c. resistance of the conductor is measured as a routine test, corrected to 20 °C and 1 km, and does not exceed the maximum value of IEC 60228 Table 2 for Class 2 aluminium conductors.
  • In accordance with IEC 60502-2 Clause 16.3, the routine partial discharge test to IEC 60885-3 raises the voltage to 2 U0 for 10 s and then reduces it to 1.73 U0, at which no discharge above the declared sensitivity of 10 pC or better is detected.
  • In accordance with IEC 60502-2 Clause 16.4 and Table 11, a power-frequency voltage of 3.5 U0 is applied for 5 min between conductor and metallic screen as a routine test: 12.5, 21, 30.5, 42 and 63 kV for the five voltage ratings.
  • In accordance with IEC 60502-2 Clause 17.9, cables rated above 3.6/6 (7.2) kV withstand a 4 h power-frequency voltage test at 4 U0 as a sample test.
  • In accordance with IEC 60502-2 Clauses 18.2.4 and 18.2.5, a type test sample is wound round a test cylinder and unwound, alternating the bending direction, for three cycles, and then shows no discharge exceeding the declared test sensitivity of 5 pC or better at 1.73 U0.
  • In accordance with IEC 60502-2 Clauses 18.2.6 and 18.2.7, tan δ is measured for ratings of 6/10 (12) kV and above, and the sample completes 20 heating cycles at 5 K to 10 K above the maximum normal conductor temperature.
  • In accordance with IEC 60502-2 Clause 18.2.8 and Table 14, each core withstands 10 positive and 10 negative impulses at 60, 75, 95, 125 or 170 kV peak according to rating, followed by a power-frequency voltage test.

Mechanical Tests

  • In accordance with IEC 60502-2 Clause 19.5 and Table 17, XLPE insulation has a tensile strength of at least 12.5 N/mm² and an elongation at break of at least 200% before ageing, with a variation of no more than ±25% after 168 h at 135 °C.
  • In accordance with IEC 60502-2 Clauses 19.6 and 19.7, the ST2 PVC sheath meets the mechanical requirements of Table 20 before and after ageing, and pieces of completed cable are aged to confirm compatibility between components.
  • In accordance with IEC 60502-2 Clause 19.23, where the insulation screen is declared strippable, the force to remove it is between 4 N and 45 N before and after ageing, leaving no damage or residue on the insulation.

Physical and Material Tests

  • In accordance with IEC 60502-2 Clause 17.5, the smallest insulation thickness is at least 0.9 times nominal minus 0.1 mm, the eccentricity ratio (tmax − tmin)/tmax does not exceed 0.15, and the smallest sheath thickness is at least 0.8 times nominal minus 0.2 mm.
  • In accordance with IEC 60502-2 Clause 17.7, the armour tape thickness is measured with a flat-nosed micrometer and does not fall more than 10% below the nominal value of Clause 13.5.
  • In accordance with IEC 60502-2 Clause 17.10 and Table 19, the XLPE hot set test at 200 °C under 20 N/cm² gives an elongation under load of not more than 175% and a permanent elongation of not more than 15%.
  • In accordance with IEC 60502-2 Clause 19.18 and Table 19, XLPE insulation shrinks by no more than 4% after 1 h at 130 °C.
  • In accordance with IEC 60502-2 Clauses 19.8 to 19.11, the ST2 PVC sheath passes the loss of mass test, the pressure test at high temperature, the low-temperature tests and the heat shock test.

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