Application
Medium-voltage armoured cables (3.6/6kV ~ 18/30kV) are widely used in the following scenarios:
Municipal Power Grid: Urban main distribution lines, ring main circuits and power supply for residential & commercial zones, commonly laid directly underground, in cable trenches or municipal utility tunnels.
Industrial Facilities: Power feeders, main power circuits and interconnection lines in factories, petrochemical plants, metallurgical works, mines and power stations, resistant to mechanical stress and mild corrosion.
Large Public Buildings: Power connection between distribution rooms, box transformers and high-voltage cabinets in shopping complexes, hospitals, data centers and large buildings, installed on cable trays or in vertical shafts.
Transportation Hubs: Medium-voltage power supply for rail transit, airports, ports, logistics parks and gas stations, suitable for outdoor and semi-outdoor environments.
Harsh Environments: Buried sections vulnerable to rodent damage, compression and vehicle rolling, as well as coastal areas and sites with slightly acidic/alkaline soil
Characteristics
Voltage Rating Uo/U (Um)
8.7/15(17.5)kV
Temperature Rating:
Maximum operating temperature of conductor: +90℃
Ambient temperature for service: -15℃ ～ +55℃
Cable laying temperature:
Not lower than 0℃ (Preheat the cable if the ambient temperature is below 0℃).
Minimum Bending Radius During Laying
Single-core cable: 15D
Three-core cable: 12D
D refers to the actual outer diameter of the cable.
Laying Methods:
Conduit laying, trench laying, tunnel laying, shaft laying, cable tray laying, etc.
Products Construction
Conductor
Circular compacted copper conductor
Conductor Screen
Semi-conductive compound (for cross-section below 500mm²)
Semi-conductive tape+semi-conductive compound (for cross-section of 500mm² and above)
Insulation
Cross-linked polyethylene (XLPE)
Insulation Screen
Strippable semi-conductive compound
Metallic Screen
Copper tape
Copper wires
Filler
Non-hygroscopic filler ropes
Wrapping Tape
Non-hygroscopic binding tape
Armour
Single-core: Stainless steel wires
Three-core: Galvanized steel wires
Inner & Outer Sheath
90℃ PVC (Non-fire-retardant type)
90℃ Fire-retardant PVC (Fire-retardant type)
Core Identification
Single-core: None
Three-core: Colour tape
Sheath Colour
Black Red
Cable Drawing :
Applicable Standards
Optional
Technical Parameters
Dimensions
| Model Code | Cross-section | Conductor Diameter | Nominal Insulation Thickness | Approx. Outer Diameter of Cable | Approx. Cable Weight |
| mm² | mm | mm | mm | kg/km | |
| YJV72-8.7/15kV | 1*25 | 5.59 | 4.5 | 27.05 | 1448.9 |
| YJV72-8.7/15kV | 1*35 | 6.62 | 4.5 | 28.25 | 1613.1 |
| YJV72-8.7/15kV | 1*50 | 7.65 | 4.5 | 29.28 | 1787.4 |
| YJV72-8.7/15kV | 1*70 | 9.21 | 4.5 | 31.01 | 2068.7 |
| YJV72-8.7/15kV | 1*95 | 10.78 | 4.5 | 33.55 | 2652.3 |
| YJV72-8.7/15kV | 1*120 | 12.12 | 4.5 | 34.89 | 2963.6 |
| YJV72-8.7/15kV | 1*150 | 13.69 | 4.5 | 36.46 | 3310.7 |
| YJV72-8.7/15kV | 1*185 | 15.21 | 4.5 | 38.15 | 3774.9 |
| YJV72-8.7/15kV | 1*240 | 17.40 | 4.5 | 40.51 | 4446.4 |
| YJV72-8.7/15kV | 1*300 | 19.55 | 4.5 | 42.66 | 5126.0 |
| YJV72-8.7/15kV | 1*400 | 22.05 | 4.5 | 46.67 | 6498.1 |
| YJV72-8.7/15kV | 1*500 | 25.00 | 4.5 | 50.76 | 7853.7 |
| YJV72-8.7/15kV | 1*630 | 28.40 | 4.5 | 54.33 | 9425.2 |
| YJV72-8.7/15kV | 1*800 | 33.70 | 4.5 | 59.97 | 11590.9 |
| YJV32-8.7/15kV | 3*25 | 5.59 | 4.5 | 50.78 | 4494.2 |
| YJV32-8.7/15kV | 3*35 | 6.62 | 4.5 | 53.17 | 4973.5 |
| YJV32-8.7/15kV | 3*50 | 7.65 | 4.5 | 55.74 | 5586.7 |
| YJV32-8.7/15kV | 3*70 | 9.21 | 4.5 | 59.28 | 6509.5 |
| YJV32-8.7/15kV | 3*95 | 10.78 | 4.5 | 63.18 | 7676.7 |
| YJV32-8.7/15kV | 3*120 | 12.12 | 4.5 | 66.41 | 8657.7 |
| YJV32-8.7/15kV | 3*150 | 13.69 | 4.5 | 71.15 | 10672.5 |
| YJV32-8.7/15kV | 3*185 | 15.21 | 4.5 | 74.78 | 12072.2 |
| YJV32-8.7/15kV | 3*240 | 17.40 | 4.5 | 80.02 | 14275.8 |
| YJV32-8.7/15kV | 3*300 | 19.55 | 4.5 | 85.17 | 16551.7 |
| YJV32-8.7/15kV | 3*400 | 22.05 | 4.5 | 91.08 | 19647.7 |
| YJV32-8.7/15kV | 3*500 | 25.00 | 4.5 | 99.69 | 23946.5 |
| YJV32-8.7/15kV | 3*630 | 28.40 | 4.5 | 109.59 | 30590.3 |
Electrical Characteristics
Single Core
| Cross-section | Max. Coductor DC Resistance at 20℃ | Max. Coductor AC Resistance at 90℃ | Capacitance | Fault Current Capacity | Positive and Negative Sequence Impedance | Zero-sequence impedance (single-end grounded | |||
| Conductor | Metallic Screen | Trefoil | Flat | Trefoil | Flat | ||||
| mm² | Ω/km | Ω/km | μF/km | kA/1s | kA/1s | Ω/km | Ω/km | Ω/km | Ω/km |
| 1×25 | 0.727 | 0.927 | 0.1778 | 3.7 | 0.73 | 0.927+j0.162 | 0.927+j0.220 | 1.075+j0.817 | 1.075+j0.730 |
| 1×35 | 0.524 | 0.668 | 0.1875 | 5.1 | 0.73 | 0.668+j0.154 | 0.668+j0.212 | 0.816+j0.803 | 0.816+j0.716 |
| 1×50 | 0.387 | 0.494 | 0.2036 | 7.3 | 0.73 | 0.494+j0.145 | 0.494+j0.203 | 0.642+j0.787 | 0.642+j0.700 |
| 1×70 | 0.268 | 0.342 | 0.2291 | 10.2 | 0.73 | 0.342+j0.138 | 0.342+j0.196 | 0.490+j0.768 | 0.490+j0.681 |
| 1×95 | 0.193 | 0.246 | 0.2561 | 13.8 | 0.73 | 0.247+j0.132 | 0.246+j0.190 | 0.394+j0.752 | 0.394+j0.665 |
| 1×120 | 0.153 | 0.196 | 0.2766 | 17.4 | 0.73 | 0.196+j0.128 | 0.196+j0.186 | 0.344+j0.739 | 0.343+j0.651 |
| 1×150 | 0.124 | 0.159 | 0.2986 | 21.8 | 0.73 | 0.159+j0.123 | 0.159+j0.181 | 0.307+j0.726 | 0.307+j0.639 |
| 1×185 | 0.0991 | 0.1271 | 0.3238 | 26.8 | 0.73 | 0.127+j0.122 | 0.127+j0.180 | 0.275+j0.709 | 0.275+j0.622 |
| 1×240 | 0.0754 | 0.0971 | 0.3582 | 34.7 | 0.73 | 0.097+j0.118 | 0.097+j0.176 | 0.245+j0.693 | 0.245+j0.606 |
| 1×300 | 0.0601 | 0.0779 | 0.3910 | 43.4 | 0.73 | 0.078+j0.114 | 0.078+j0.172 | 0.226+j0.679 | 0.226+j0.592 |
| 1×400 | 0.0470 | 0.0616 | 0.4299 | 57.8 | 0.73 | 0.062+j0.110 | 0.061+j0.168 | 0.210+j0.661 | 0.209+j0.574 |
| 1×500 | 0.0366 | 0.0487 | 0.4781 | 72.2 | 0.73 | 0.050+j0.107 | 0.049+j0.165 | 0.197+j0.645 | 0.197+j0.558 |
| 1×630 | 0.0283 | 0.0388 | 0.5309 | 90.8 | 0.73 | 0.040+j0.105 | 0.039+j0.163 | 0.188+j0.629 | 0.187+j0.541 |
| 1×800 | 0.0221 | 0.0315 | 0.6209 | 115.3 | 0.73 | 0.033+j0.104 | 0.031+j0.162 | 0.181+j0.607 | 0.179+j0.520 |
Three Cores
| Cross-section | Max. Coductor DC Resistance at 20℃ | Max. Coductor AC Resistance at 90℃ | Capacitance | Inductance | Impedance | Fault Current Capacity | Positive and Negative Sequence Impedance | Zero-sequence impedance (single-end grounded） | |
| Conductor | Metallic Screen | ||||||||
| mm² | Ω/km | Ω/km | μF/km | mH/km | Ω/km | kA/1s | kA/1s | Ω/km | Ω/km |
| 3×25 | 0.727 | 0.927 | 0.1778 | 0.4643 | 0.9385 | 3.7 | 1.92 | 0.927+j0.141 | 1.075+j0.859 |
| 3×35 | 0.524 | 0.668 | 0.1875 | 0.4516 | 0.6832 | 5.1 | 1.92 | 0.668+j0.133 | 0.817+j0.844 |
| 3×50 | 0.387 | 0.494 | 0.2036 | 0.4336 | 0.5121 | 7.3 | 1.92 | 0.494+j0.125 | 0.642+j0.827 |
| 3×70 | 0.268 | 0.342 | 0.2291 | 0.4022 | 0.3647 | 10.2 | 1.92 | 0.342+j0.119 | 0.490+j0.807 |
| 3×95 | 0.193 | 0.247 | 0.2561 | 0.3834 | 0.2745 | 13.8 | 1.92 | 0.247+j0.114 | 0.395+j0.788 |
| 3×120 | 0.153 | 0.196 | 0.2766 | 0.3717 | 0.2280 | 17.4 | 1.92 | 0.196+j0.110 | 0.344+j0.773 |
| 3×150 | 0.124 | 0.159 | 0.2986 | 0.3585 | 0.1949 | 21.8 | 1.92 | 0.159+j0.107 | 0.307+j0.760 |
| 3×185 | 0.0991 | 0.1276 | 0.3238 | 0.3481 | 0.1680 | 26.8 | 1.92 | 0.128+j0.104 | 0.276+j0.745 |
| 3×240 | 0.0754 | 0.0978 | 0.3582 | 0.3364 | 0.1440 | 34.7 | 1.92 | 0.098+j0.100 | 0.246+j0.728 |
| 3×300 | 0.0601 | 0.0788 | 0.3910 | 0.3258 | 0.1292 | 43.4 | 1.92 | 0.079+j0.098 | 0.227+j0.712 |
| 3×400 | 0.0470 | 0.0628 | 0.4299 | 0.3167 | 0.1176 | 57.8 | 1.92 | 0.063+j0.093 | 0.211+j0.694 |
| 3×500 | 0.0366 | 0.0504 | 0.4781 | 0.2997 | 0.1068 | 72.2 | 1.92 | 0.050+j0.092 | 0.199+j0.676 |
| 3×630 | 0.0283 | 0.0409 | 0.5309 | 0.2885 | 0.0994 | 90.8 | 1.92 | 0.041+j0.090 | 0.189+j0.658 |
Correction factors for ampacity
| Conductor operating temperature (℃) | Temperature in air (℃) | |||||||
| 20 | 25 | 30 | 35 | 40 | 45 | 50 | 55 | |
| 90 | 1.21 | 1.16 | 1.11 | 1.06 | 1.00 | 0.94 | 0.88 | 0.81 |
| Conductor operating temperature (℃) | Temperature in soil (℃) | |||||
| 10 | 15 | 20 | 25 | 30 | 35 | |
| 90 | 1.11 | 1.07 | 1.04 | 1.00 | 0.96 | 0.92 |
| Conductor operating temperature (℃) | Soil thermal resistivity (K·m/W) -direct burial | ||||||
| 0.7 | 1 | 1.2 | 1.5 | 2 | 2.5 | 3 | |
| 90 | 1.13 | 1.00 | 0.93 | 0.86 | 0.76 | 0.69 | 0.64 |
| Conductor operating temperature (℃) | Soil thermal resistivity (K·m/W) -conduit burial | ||||||
| 0.7 | 1 | 1.2 | 1.5 | 2 | 2.5 | 3 | |
| 90 | 1.08 | 1.00 | 0.96 | 0.90 | 0.82 | 0.77 | 0.72 |
| Conductor operating temperature (℃)) | Burial depth in soil (m) -direct burial | |||||
| 0.5 | 0.7 | 1.0 | 1.5 | 2.0 | 2.5 | |
| 90 | 1.07 | 1.03 | 1.00 | 0.96 | 0.94 | 0.92 |
| Conductor operating temperature (℃) | Burial depth in soil (m) – in conduit | |||||
| 0.5 | 0.7 | 1.0 | 1.5 | 2.0 | 2.5 | |
| 90 | 1.04 | 1.02 | 1.00 | 0.98 | 0.96 | 0.95 |
For single-core cables arranged in a trefoil formation, the cables are in contact with each other; when installed in ducts, the ducts are in contact with each other.
For single-core cables arranged in parallel with spacing, the axial distance between cables is 2 times the cable outer diameter.
For calculations under base conditions, the burial depth in soil is taken as 1.0 m, and the soil thermal resistivity is taken as 1.0 K·m/W.
Depending on the soil type, the corresponding soil conditions and meteorological conditions for different thermal resistivities are approximately as follows:
- 0.7: Soil condition: Very wet; Meteorological condition: Continuous rainfall
- 1.0: Soil condition: Wet; Meteorological condition: Normal rainfall
- 2.0: Soil condition: Dry; Meteorological condition: Infrequent rainfall
- 3.0: Soil condition: Very dry; Meteorological condition: Rare or no rainfall
The ducts are plastic pipes. (Assume the duct inner diameter is 1.5 times the cable outer diameter, and the duct wall thickness is 6% of the duct inner diameter.)
The metallic screen is not directly grounded at both ends.
FAQ
Multi-core Power Cables
Galvanized steel wire armoring is the preferred choice. The vector sum of three-phase currents in multi-core cables is nearly zero, so no significant eddy current loss occurs on the armor. Steel wire features high mechanical strength, excellent compression resistance, tensile resistance and external damage protection.
Single-core Power Cables (AC System)
Ordinary steel wire armoring is strictly prohibited. When alternating current flows through a single-core cable, eddy currents will be induced in the metal armor, leading to severe overheating and power loss, and even accelerating insulation aging and causing cable failures. Adopt non-magnetic stainless steel wire/tape , aluminum wire , aluminum alloy wire or aluminum tape armoring to avoid eddy current issues.
Steel Tape Armoring (STA): Suitable for direct burial and tunnel laying, with strong resistance to lateral pressure and lower cost. Ordinary steel tape not allowed for single-core AC cables, as eddy current will cause overheating, reduce current-carrying capacity and even lead to cable burnout.
Steel Wire Armoring (SWA): Features high tensile strength, ideal for vertical shaft, underwater and vertical laying. Non-magnetic steel wire can be used for single-core cables, while its lateral pressure resistance is weaker than steel tape.
Selection principle: For single-core AC medium voltage cables, prioritize non-magnetic armoring materials (stainless steel wire, aluminum alloy wire). For three-core cables, steel tape or steel wire armoring can be selected as required.
Lay 10cm fine sand cushion at the bottom of the trench, and cover another 10cm fine sand above the cable after laying to prevent the armor from being scratched by hard objects.
Install concrete protection slabs or warning tapes above the cable to avoid external mechanical damage.
Metal conduits must be installed when crossing roads and buildings, and both ends of conduits shall be sealed for waterproofing.
