21/35kV XLPE Insulated Power Cable

21/35kV XLPE Insulated Power Cable from Qiancheng meets the erection requirements of high-voltage main transmission lines such as urban power-grid renovation and power transmission for industrial-mining substations.

Product Definition and Introduction

Full Product Name

Qiancheng 21/35kV XLPE Insulated Power Cable. It complies with dual standards GB/T 12706 and IEC 60840. With rated voltage of 21/35kV, it serves as a major medium-and-high-voltage power transmission cable.

Enterprise Qualification Support

Our factory has 20-year experience in cable manufacturing. It is equipped with a CNAS-accredited testing laboratory. Full-range qualifications can be verified on the official website. Each batch of cables comes with quality-inspection reports and factory certificates, and all qualification documents are traceable for verification.

Verified Practical Project Cases

More than 800 000 meters of Qiancheng 21/35kV XLPE Insulated Power Cable have been supplied for substation expansion, high-voltage power-supply renovation in mining areas and overall power-distribution projects of industrial parks in Shandong region. Field operation tests prove no insulation aging or breakdown after 3-year continuous full-load operation.

Product Specifications and Technical Parameters Table

Internal Cable Structure

Conductor

High-purity oxygen-free compacted stranded copper conductor. Measured DC resistance of the conductor is strictly kept within national-standard limits, featuring low conductive loss. Measured temperature rise under heavy-current load ≤65K.

Triple-co-extruded XLPE Insulation Layer

Manufactured by integrated triple-co-extrusion process. Insulation thickness is uniform without air gaps. It can stably withstand 42 kV power-frequency voltage test for 1 hour without breakdown. It serves as the core pressure-bearing structure of Qiancheng 21/35kV XLPE Insulated Power Cable.

Shielding Layer

Combined structure of inner semi-conductive shield and outer semi-conductive shield, which equalizes electric-field distribution and prevents insulation damage caused by local electric-field concentration.

Armoring & Outer Sheath

Steel-tape armoring resists crushing force and damage from underground excavation. HDPE outer sheath provides acid-alkali corrosion resistance and UV-aging resistance, suitable for multiple laying scenarios: direct burial, conduit installation and cable-tray routing.

Core Product Advantages

Excellent Insulation Stability

XLPE cross-linked material has a temperature resistance class of 90℃. It can withstand short-term overload at 250℃ for 5 seconds without melting. Insulation hardly degrades under long-term heavy-load transmission, reducing frequency of line-fault maintenance.

Full-traceable Quality Control

Test procedures from copper-material incoming inspection to finished-cable delivery. Key test data including voltage-withstand, partial discharge and thermal aging are recorded in the system. Buyers can access all original test data via batch numbers.

Lower Loss & Higher Energy-saving

Performance Compact-formed conductor achieves a filling coefficient above 92%. Compared with ordinary loosely-stranded cables, line voltage drop decreases by around 7% in actual measurement, saving power-consumption loss during long-term power-grid operation.

Strong Customization Compatibility

Customizable Qiancheng 21/35kV XLPE Insulated Power Cable options: LSZH halogen-free low-smoke sheath, Class-A flame-retardant type and fire-resistant type, adapting to special fire-protection working conditions such as tunnels and enclosed power-distribution rooms.

Standard Installation & Laying Guidelines

Direct-buried Laying

Lay fine-sand cushion on trench bottom before laying. Burial depth of armored cables ≥0.8 m. Avoid areas subject to heavy-vehicle rolling. Complete route marking after construction to prevent cable cutting-off by later excavation.

Cable-tray / Tunnel Laying

For single Qiancheng 21/35kV XLPE Insulated Power Cable, laying bending radius shall be no less than 15 times cable outer diameter. Reserve heat-dissipation gaps for multi-cable arrangement to avoid overheating caused by dense stacking.

Laying Environment Restrictions

Avoid long-term immersion in strongly-corrosive sewage and unprotected outdoor exposure under intense sunlight. Pre-heat cables before laying at temperatures below 0℃ to prevent brittle cracking of outer sheath.

Completion Acceptance

Power-frequency voltage-withstand retest shall be performed after laying completion. Power-on switching is allowed only after passing tests. Our professional technicians can be dispatched to provide on-site acceptance guidance.

FAQ

Q1: What practical benefits can the compacted-stranded conductor process of 21/35kV XLPE Insulated Power Cable bring?

A: Compared with a conventional loosely stranded conductor, the compacted construction can reduce conductor gaps and support lower electrical resistance. It also helps manage temperature rise under high-current loading, which is useful for long-term power transmission applications.

Q2: What short-term overload temperature can the XLPE insulation withstand?

A: The long-term operating temperature of XLPE insulation is 90℃. Under short-circuit or short-duration overload conditions, the insulation can withstand temperatures of up to 250℃ for a specified short period. Actual operating limits should follow the applicable cable standard and installation conditions.

Q3: What functions do the inner and outer semi-conductive shields perform?

A: The inner and outer semi-conductive layers help control the electric-field distribution around the insulation. By reducing localized electric-field concentration at the conductor and insulation interfaces, the shielding system supports stable insulation performance during high-voltage operation.

Q4: What are the key construction points for direct-buried installation?

A: An armored construction is generally preferred where direct burial requires additional mechanical protection. A suitable sand cushion can be provided at the bottom of the trench, and the burial depth should meet the applicable project specification. Cable routes should also be clearly marked after installation, particularly in areas where later excavation or vehicle traffic may occur.

Q5: What are the bending and arrangement requirements for cable trays or tunnel installation?

A: The minimum bending radius for a single cable should not be less than 15 times its outer diameter unless the applicable specification states otherwise. When several cables are installed in parallel, adequate spacing should be maintained for heat dissipation. Excessive stacking should be avoided to prevent unnecessary temperature rise.

Q6: What environments are unsuitable for direct laying?

A: Long-term exposure to strongly corrosive sewage and unprotected outdoor conditions with intense sunlight should be avoided unless the selected cable construction has been verified for these environments. For installation at ambient temperatures below 0℃, appropriate preheating measures should be taken to reduce the risk of brittle damage to the sheath.

Q7: What tests should be completed before energizing the installed cable?

A: After installation, the required electrical inspection and power-frequency voltage withstand test should be completed according to the applicable standard and project requirements. The circuit should only be energized after the required tests have been passed and the installation has been accepted. Technical assistance can be provided for project-specific acceptance requirements.