Abstract: GB/T 18890.2-2015 is a key national recommended standard in China that specifies the technical requirements, test methods, and acceptance criteria for 220 kV (Um=252 kV) cross-linked polyethylene (XLPE) insulated power cables. This standard, which replaced the former guiding technical document GB/Z 18890.2-2002, plays a crucial role in standardizing the production, application, and quality control of high-voltage power cables in China’s power grid construction. This article elaborates on the background, core technical requirements, key test specifications, and industrial value of GB/T 18890.2-2015, aiming to provide a comprehensive technical reference for professionals in the power cable industry.

1. Introduction

With the rapid advancement of urbanization and industrialization in China, the demand for reliable and efficient power transmission has surged, particularly in the field of 220 kV power grids. Prior to 2015, the widespread application of 220 kV XLPE insulated power cables was accompanied by issues such as inconsistent product quality and fragmented technical indicators, which posed potential risks to grid safety and stable operation. To address these challenges, GB/T 18890.2-2015, titled “Power cables with cross-linked polyethylene insulation and their accessories for rated voltage of 220 kV (Um=252 kV)—Part 2: Power cables”, was issued on October 9, 2015, and officially implemented on May 1, 2016 . As part of the GB/T 18890 standard series, this document focuses on the technical requirements for the cable itself, forming a complete technical standard system with GB/T 18890.1 (test methods and general requirements) and GB/T 18890.3 (accessories). It also references international standards such as IEC 60183, balancing domestic operating conditions with technical universality .

Compared with its predecessor GB/Z 18890.2-2002, GB/T 18890.2-2015 has undergone significant upgrades: it was transformed from a guiding technical document to a recommended standard, with revised terminology and expanded content covering aspects such as operational characteristics, current-carrying capacity, and new structural designs (e.g., split conductors and metal-plastic composite sheaths) . These revisions have enhanced the standard’s applicability and rigor, making it a de facto “hard constraint” in the industry for quality assessment and project acceptance.

2. Scope and Core Positioning

GB/T 18890.2-2002 specifies the model designation, technical requirements, testing and acceptance rules, packaging, transportation, and storage of fixedly installed 220 kV (Um=252 kV) XLPE insulated power cables . It applies to single-core cables used under normal installation and operating conditions but excludes special-purpose cables such as submarine cables.

The core positioning of this standard lies in establishing a unified technical benchmark for the entire lifecycle of 220 kV XLPE cables, from design and production to inspection and application. Although it is a recommended standard, its alignment with the core needs of power grid safety has made it an essential reference for manufacturers, utilities, and inspection institutions. By defining clear requirements for materials, structure, and performance, the standard helps eliminate substandard products, reduce power outages caused by cable failures, and lower the total lifecycle cost of cables . Additionally, it provides technical support for new energy grid integration, facilitating the transition of China’s energy structure.

3. Core Technical Requirements

3.1 Cable Structure and Component Requirements

GB/T 18890.2-2015 defines the standard structure of 220 kV XLPE cables, which consists of conductor, conductor screen, insulation layer, insulation screen, metal screen, armor layer, and outer sheath . Each component has strict design and material specifications to ensure synergistic performance:

• Conductor: Copper or aluminum conductors are permitted, with a purity of not less than 99.9% for copper and 99.7% for aluminum. The conductor is stranded, with a single wire diameter not exceeding 4.0 mm and specified stranding pitches. The cross-sectional area is optimized to enhance current-carrying capacity; for example, a 2500 mm² copper conductor can achieve a current-carrying capacity of 1250 A in a 25℃ environment .
• Conductor and Insulation Screens: The semi-conductive conductor screen (thickness: 0.8–1.2 mm) and insulation screen are critical for uniform electric field distribution. The volume resistivity of the screen material shall not exceed 100 Ω·cm, and the minimum thickness of the semi-conductive screen is explicitly required to prevent electric field distortion .
• Insulation Layer: Made of high-purity XLPE material, the insulation layer must have a thickness of not less than 17 mm to ensure voltage resistance. The XLPE material requires strict purity control (impurity particle size ≤ 5 μm), a cross-linking degree of 65%–85%, and excellent aging resistance (tensile strength retention rate ≥ 80% and elongation at break retention rate ≥ 70% after 168 hours of thermal aging at 135℃) .
• Metal Screen and Sheath: The standard adds requirements for metal screens and introduces new sheath types such as metal-plastic composite sheaths and copper sheaths. It also revises the material requirements for lead and aluminum sheaths and specifies technical criteria for buffer layers, longitudinal water-blocking layers, and radial water-blocking layers to enhance mechanical protection and water resistance .

3.2 Voltage Adaptation and Operational Performance

The key parameter Um=252 kV (maximum operating voltage) is scientifically determined based on the operating characteristics of 220 kV power grids. Considering voltage fluctuations in actual operation, the standard sets the maximum operating voltage at 1.15 times the rated voltage, balancing grid voltage regulation needs with cable safety margins . The cable’s long-term allowable operating temperature is 90℃, and the maximum temperature during short circuits (lasting 5 seconds) is 250℃. The insulation resistance constant at 20℃ shall not be less than 3.6 × 10³ MΩ·km .

To address transient overvoltages caused by lightning or switching operations, the standard requires the cable to have excellent partial discharge resistance and specifies coordination with protective devices such as surge arresters to form a comprehensive overvoltage protection system .

4. Key Test Specifications

GB/T 18890.2-2015 revises and expands the cable test items, emphasizing full-process quality control from raw materials to finished products. Key test requirements include:

• Power Frequency Voltage Withstand Test: At 20℃, apply a voltage of 395 kV for 1 hour without breakdown .
• Impulse Voltage Withstand Test: Apply a peak voltage of 1050 kV, 10 times for both positive and negative polarities, without flashover. The test must be conducted in a shielded environment to avoid external interference, and insulation resistance must be measured after the test to ensure no performance degradation .
• Partial Discharge Test: The partial discharge quantity shall not exceed 5 pC to detect insulation defects early and prevent breakdown .
• Material Performance Tests: Include thermal aging, low-temperature resistance, ozone resistance, and environmental stress cracking resistance tests for insulation and sheath materials, in accordance with referenced standards such as GB/T 2951 series .
• Mechanical and Physical Tests: Cover thickness measurement, tensile strength, elongation at break, and corrosion resistance tests to ensure mechanical integrity .

5. Industrial Value and Significance

GB/T 18890.2-2015 has exerted profound impacts on China’s power cable industry and power grid development:

1. Enhancing Grid Safety and Reliability: By standardizing technical requirements and strict testing, the standard reduces cable-related faults, minimizing power outages and ensuring stable power supply .
2. Standardizing Market Competition: The unified technical benchmark eliminates substandard products, promoting fair competition and driving technological progress in the industry.
3. Supporting Energy Structure Transition: The standard provides reliable technical support for new energy grid integration, facilitating the development of renewable energy sources such as wind and solar power.
4. Facilitating International Trade: With the implementation of China’s “Belt and Road” initiative, the demand for foreign-language versions of national standards has increased. The translation of GB/T 18890.2-2015 helps promote the international application of Chinese power cable products and technologies .

GB/T 18890.2-2015 is a foundational technical standard for 220 kV XLPE insulated power cables in China, integrating scientific design principles, practical engineering experience, and international technical references. Its strict requirements for cable structure, material performance, and test methods have effectively improved the quality and reliability of high-voltage power cables, providing strong support for the safe and efficient operation of China’s power grid. As the power industry continues to develop, the standard will play an increasingly important role in promoting technological innovation, supporting new energy development, and facilitating international cooperation. It is essential for manufacturers, utilities, and research institutions to fully implement and adhere to the standard to drive the high-quality development of the power cable industry.

References

[1] GB/T 18890.2-2015, Power cables with cross-linked polyethylene insulation and their accessories for rated voltage of 220 kV (Um=252 kV)—Part 2: Power cables. General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China, Standardization Administration of the People’s Republic of China, 2015.

[2] IEC 60183, Guidance for the selection of high-voltage a.c. cable systems.

[3] GB/T 18890.1-2015, Power cables with cross-linked polyethylene insulation and their accessories for rated voltage of 220 kV (Um=252 kV)—Part 1: Test methods and requirements.