1. Introduction | 引言

English: The (N)TSCGEWÖU cable type represents a specialized category of medium-voltage power cables designed for demanding applications in mining, tunneling, harbor cranes, and heavy-duty industrial environments. These cables feature 3GI3 grade Ethylene-Propylene Rubber (EPR) insulation, which must maintain dielectric integrity under extreme mechanical stress, moisture exposure, and electrical field conditions. Understanding the aging behavior of the dielectric loss factor (tan delta, tan δ) is critical for predictive maintenance and ensuring operational safety in these mission-critical applications.

中文：(N)TSCGEWÖU 电缆类型是专为采矿、隧道工程、港口起重机和重型工业环境等苛刻应用而设计的中压电力电缆专业类别。这些电缆采用 3GI3 等级乙丙橡胶 (EPR) 绝缘，必须在极端机械应力、湿气暴露和电场条件下保持介电完整性。了解介电损耗因数（tan delta，tan δ）的老化行为对于预测性维护和确保这些关键任务应用中的运行安全至关重要。

2. Understanding Tan Delta (Dielectric Loss Factor) | 理解 Tan Delta（介电损耗因数）

2.1 Physical Principle | 物理原理

English: Tan delta testing measures the ratio of resistive current to capacitive current flowing through cable insulation when subjected to an AC voltage. In an ideal insulator with 100% purity, current flow would be purely capacitive with a 90-degree phase shift relative to applied voltage. However, real-world insulation materials contain impurities such as moisture, contaminants, and degradation byproducts that introduce resistive current components. The tangent of the loss angle (δ) quantifies this deviation from ideal capacitive behavior, with increasing tan δ values indicating greater insulation degradation.

中文：Tan delta 测试测量在交流电压作用下流过电缆绝缘的电阻电流与电容电流之比。在 100% 纯度的理想绝缘体中，电流将是纯电容性的，相对于施加电压有 90 度相移。然而，实际绝缘材料含有水分、污染物和降解副产物等杂质，这些会引入电阻电流成分。损耗角 (δ) 的正切量化了这种与理想电容行为的偏差，tan δ 值增加表明绝缘退化更严重。

2.2 Testing Methodology | 测试方法

English: According to IEEE 400.2 standards, tan delta measurements are performed using Very Low Frequency (VLF) AC voltage at 0.1 Hz. This low frequency reduces power requirements by a factor of 600 compared to 60 Hz testing while enhancing measurement sensitivity. Testing typically progresses through voltage increments of 0.5U₀, 1.0U₀, 1.5U₀, and 2.0U₀ (where U₀ is the rated phase-to-ground voltage), with 6-10 measurements recorded at each level to assess stability and voltage dependency.

中文：根据 IEEE 400.2 标准，tan delta 测量使用 0.1 Hz 的极低频 (VLF) 交流电压进行。与 60 Hz 测试相比，这种低频将功率需求降低了 600 倍，同时提高了测量灵敏度。测试通常以 0.5U₀、1.0U₀、1.5U₀ 和 2.0U₀（其中 U₀ 是额定相对地电压）的电压增量进行，每个级别记录 6-10 次测量以评估稳定性和电压依赖性。

3. 3GI3 EPR Insulation Characteristics | 3GI3 EPR 绝缘特性

3.1 Material Specification | 材料规格

English: The 3GI3 designation refers to high-grade EPR compound meeting DIN VDE 0207 Part 20 specifications. This insulation type is characterized by mineral filler content (typically clay-based), which provides enhanced mechanical properties and resistance to partial discharge activity compared to unfilled polyethylene (XLPE) insulations. The filled nature of 3GI3 EPR creates a more hydrophilic dielectric with higher ionic content, resulting in different aging mechanisms compared to XLPE materials.

中文：3GI3 标识是指符合 DIN VDE 0207 Part 20 规范的高等级 EPR 化合物。与未填充的交联聚乙烯 (XLPE) 绝缘相比，这种绝缘类型的特点是含有矿物填料（通常为粘土基），可提供增强的机械性能和抗局部放电活动能力。3GI3 EPR 的填充性质创造了一种具有更高离子含量的更亲水的电介质，导致与 XLPE 材料相比不同的老化机制。

3.2 Water Treeing Resistance | 抗水树枝性能

English: Research demonstrates that EPR insulations exhibit superior resistance to water tree formation compared to XLPE materials. Water trees are microscopic, tree-shaped channels caused by moisture infiltration that eventually lead to electrical tree formation and insulation failure. Studies have shown that in filled EPR insulations, water tree initiation typically occurs from contaminant sites rather than from the bulk polymer, and the greater ionic content may contribute to water treeing resistance by increasing water conductivity within the dielectric to levels where self-propagating trees cannot readily develop.

中文：研究表明，与 XLPE 材料相比，EPR 绝缘表现出优异的抗水树枝形成能力。水树枝是由水分渗透引起的微观树状通道，最终导致电树枝形成和绝缘故障。研究表明，在填充 EPR 绝缘中，水树枝的萌发通常发生在污染物位点而不是聚合物主体，更高的离子含量可能通过将介电内的水电导率提高到自我传播树枝不易发展的水平来帮助抗水树枝。

4. Tan Delta Changes During Cable Aging | 电缆老化期间 Tan Delta 的变化

4.1 Early-Stage Aging (0-10 Years) | 早期老化（0-10年）

English: During initial service periods, 3GI3 EPR insulation in (N)TSCGEWÖU cables typically exhibits stable tan delta values in the range of 10-30 × 10⁻³ at U₀ voltage level when measured at 0.1 Hz. The insulation maintains low resistive current components, with minimal moisture ingress and contaminant accumulation. Standard deviation values remain below 0.1 × 10⁻³, indicating excellent measurement stability. Delta tan delta (tip-up between 0.5U₀ and 1.5U₀) values stay below 20 × 10⁻³, demonstrating voltage-independent dielectric loss characteristics typical of healthy insulation.

中文：在初始使用期间，(N)TSCGEWÖU 电缆中的 3GI3 EPR 绝缘在 0.1 Hz 测量时，在 U₀ 电压水平下通常表现出 10-30 × 10⁻³ 范围内的稳定 tan delta 值。绝缘保持低电阻电流成分，水分渗透和污染物积累最少。标准差值保持在 0.1 × 10⁻³ 以下，表明测量稳定性极好。Delta tan delta（0.5U₀ 和 1.5U₀ 之间的尖端上升）值保持在 20 × 10⁻³ 以下，显示出健康绝缘典型的电压无关介电损耗特性。

4.2 Mid-Stage Aging (10-25 Years) | 中期老化（10-25年）

English: As cables accumulate service years in harsh environments, moisture penetration through micro-cracks and exposure to thermal cycling begin to manifest in tan delta measurements. Mean tan delta values at U₀ may increase to the 30-50 × 10⁻³ range. This elevation reflects increased resistive current paths through the insulation. Importantly, EPR insulations tend to age non-uniformly, with degradation localized to specific high-stress regions rather than distributed throughout the cable length. The filled nature of 3GI3 EPR provides buffering against rapid degradation progression during this phase.

中文：随着电缆在恶劣环境中累积使用年限，通过微裂纹的水分渗透和热循环暴露开始在 tan delta 测量中显现。U₀ 处的平均 tan delta 值可能增加到 30-50 × 10⁻³ 范围。这种升高反映了绝缘体中电阻电流路径的增加。重要的是，EPR 绝缘往往老化不均匀，退化局限于特定的高应力区域，而不是分布在整个电缆长度上。3GI3 EPR 的填充性质在此阶段提供了抵抗快速退化进展的缓冲。

4.3 Advanced Aging (25+ Years) | 高级老化（25年以上）

English: Extended service life in wet underground or submerged environments can lead to significant tan delta increases as water tree channels accumulate and oxidation products dissolve in the insulation. Cables requiring further study or action typically exhibit mean tan delta values exceeding 50 × 10⁻³ at U₀, standard deviations above 0.5 × 10⁻³, and delta tan delta values surpassing 80 × 10⁻³. A critical indicator of severely degraded insulation is strong “tip-up” behavior, where tan delta increases substantially with applied voltage, reflecting voltage-dependent conduction through degraded material. Field studies of 30+ year-old EPR cables in wet environments have demonstrated that while some degradation occurs, EPR materials generally maintain higher reliability than comparable XLPE installations due to their inherent resistance to water tree propagation.

中文：在潮湿地下或浸没环境中的延长使用寿命可能导致 tan delta 显著增加，因为水树枝通道积累且氧化产物溶解在绝缘中。需要进一步研究或采取行动的电缆通常在 U₀ 处表现出超过 50 × 10⁻³ 的平均 tan delta 值，标准差高于 0.5 × 10⁻³，delta tan delta 值超过 80 × 10⁻³。严重退化绝缘的关键指标是强”尖端上升”行为，其中 tan delta 随施加电压大幅增加，反映了通过退化材料的电压依赖性传导。对潮湿环境中 30 年以上 EPR 电缆的现场研究表明，虽然发生了一些退化，但由于其固有的抗水树枝传播能力，EPR 材料通常比可比的 XLPE 安装保持更高的可靠性。

5. IEEE 400.2 Assessment Criteria for EPR Insulation | EPR 绝缘的 IEEE 400.2 评估标准

Note | 注意: These criteria apply to cables up to 1.5 km in length tested at 0.1 Hz. For longer cables, trending analysis is recommended as the primary diagnostic approach. | 这些标准适用于在 0.1 Hz 下测试的长度达 1.5 公里的电缆。对于较长的电缆，建议将趋势分析作为主要诊断方法。

6. Aging Mechanisms Specific to (N)TSCGEWÖU Applications | (N)TSCGEWÖU 应用特有的老化机制

6.1 Mechanical Stress Effects | 机械应力效应

English: The (N)TSCGEWÖU cable design incorporates anti-torsion polyester braiding between inner and outer sheaths, reflecting its intended use in winding drums, cranes, and mobile equipment subjected to continuous flexing and torsional loads. These mechanical stresses can accelerate insulation aging by creating micro-voids and crack propagation points where moisture accumulation occurs. Tan delta testing can detect the dielectric degradation resulting from mechanically-induced defects, though it cannot discriminate between mechanical damage and purely electrical/chemical aging without complementary partial discharge (PD) diagnostics.

中文：(N)TSCGEWÖU 电缆设计在内护套和外护套之间结合了抗扭转聚酯编织，反映了其在经受持续弯曲和扭转负载的卷筒、起重机和移动设备中的预期用途。这些机械应力可能通过产生微空隙和裂纹传播点（水分积累发生的地方）来加速绝缘老化。Tan delta 测试可以检测由机械诱导缺陷导致的介电退化，尽管在没有互补局部放电 (PD) 诊断的情况下无法区分机械损伤和纯电气/化学老化。

6.2 Submersible Environment Considerations | 可浸没环境考虑因素

English: Many (N)TSCGEWÖU installations operate in water depths up to 500 meters or in sewage/saltwater environments where continuous moisture exposure accelerates water ingress into the insulation system. The 5GM5 chloroprene rubber outer sheath provides water barrier protection, but prolonged submersion can lead to moisture migration through terminations and splices. Tan delta measurements conducted on nuclear power plant cables and similar submerged applications show that moisture-related degradation typically manifests as elevated tan delta values with positive tip-up characteristics, while cables may still maintain adequate AC breakdown strength until critical deterioration thresholds are exceeded.

中文：许多 (N)TSCGEWÖU 安装在高达 500 米的水深或污水/盐水环境中运行，持续的水分暴露加速了水分侵入绝缘系统。5GM5 氯丁橡胶外护套提供防水屏障保护，但长期浸没可能导致水分通过终端和接头迁移。对核电站电缆和类似浸没应用进行的 Tan delta 测量表明，与水分相关的退化通常表现为升高的 tan delta 值和正尖端上升特性，而电缆可能仍保持足够的交流击穿强度，直到超过临界退化阈值。

7. Predictive Maintenance Strategies | 预测性维护策略

7.1 Baseline Establishment | 基线建立

English: For (N)TSCGEWÖU cable assets, establishing baseline tan delta measurements within the first 1-3 years of service provides critical reference data for trend analysis. Initial measurements should be conducted following IEEE 400.2 protocols, with results documented including ambient temperature, test voltage levels, frequency, and environmental conditions. This baseline enables detection of deviation patterns that indicate accelerated aging or localized defects.

中文：对于 (N)TSCGEWÖU 电缆资产，在服务的前 1-3 年内建立基线 tan delta 测量为趋势分析提供了关键参考数据。初始测量应遵循 IEEE 400.2 协议进行，记录的结果包括环境温度、测试电压水平、频率和环境条件。此基线使能够检测指示加速老化或局部缺陷的偏差模式。

7.2 Testing Frequency Recommendations | 测试频率建议

English: Based on nuclear power plant experience and industry best practices, the following testing intervals are recommended for (N)TSCGEWÖU cables: For cables 0-10 years old in normal service conditions, testing every 5 years; for cables 10-20 years old or operating in harsh environments (submerged, high mechanical stress), testing every 2-3 years; for cables exceeding 20 years or showing elevated tan delta trends, annual testing with consideration for replacement planning. Cables exhibiting “Further Study Advised” or “Action Required” criteria should undergo immediate retesting and engineering evaluation.

中文：根据核电站经验和行业最佳实践，建议对 (N)TSCGEWÖU 电缆采用以下测试间隔：对于正常使用条件下 0-10 年的电缆，每 5 年测试一次；对于 10-20 年的电缆或在恶劣环境（浸没、高机械应力）中运行的电缆，每 2-3 年测试一次；对于超过 20 年或显示升高 tan delta 趋势的电缆，每年测试并考虑更换计划。表现出”建议进一步研究”或”需要行动”标准的电缆应立即进行重新测试和工程评估。

7.3 Integration with Other Diagnostics | 与其他诊断的集成

English: While tan delta testing provides valuable global assessment of insulation condition, it should be complemented with partial discharge (PD) testing for comprehensive cable health evaluation. PD diagnostics can locate specific defect sites that tan delta cannot pinpoint, as tan delta represents an average measurement across the entire cable system. Combined tan delta and PD testing during monitored withstand tests (per IEEE 400.2) enables both global condition assessment and localized fault detection, optimizing decision-making for maintenance interventions.

中文：虽然 tan delta 测试提供了绝缘状态的有价值的全局评估，但应与局部放电 (PD) 测试相结合以进行全面的电缆健康评估。PD 诊断可以定位 tan delta 无法精确定位的特定缺陷位置，因为 tan delta 代表整个电缆系统的平均测量。在监测耐压测试期间（根据 IEEE 400.2）结合 tan delta 和 PD 测试使能够进行全局状态评估和局部故障检测，优化维护干预的决策。

8. Conclusion | 结论

English: The dielectric loss factor (tan delta) of 3GI3 EPR insulation in (N)TSCGEWÖU cables exhibits characteristic aging patterns that reflect the combined effects of electrical stress, moisture exposure, thermal cycling, and mechanical loading. During normal service, tan delta values typically remain below 30 × 10⁻³ for the first 10 years, gradually increasing to 30-50 × 10⁻³ during mid-life (10-25 years), and potentially exceeding 50 × 10⁻³ in advanced aging stages beyond 25 years. The filled EPR formulation demonstrates superior resistance to water treeing compared to XLPE alternatives, making it particularly suitable for harsh (N)TSCGEWÖU operating environments. Regular tan delta monitoring according to IEEE 400.2 guidelines, combined with trending analysis and complementary PD testing, enables effective predictive maintenance strategies that optimize cable asset lifecycle management and minimize unplanned outages.

中文：(N)TSCGEWÖU 电缆中 3GI3 EPR 绝缘的介电损耗因数（tan delta）表现出特征性老化模式，反映了电应力、水分暴露、热循环和机械负载的综合效应。在正常使用期间，tan delta 值在前 10 年通常保持在 30 × 10⁻³ 以下，在中期寿命（10-25 年）逐渐增加到 30-50 × 10⁻³，在超过 25 年的高级老化阶段可能超过 50 × 10⁻³。与 XLPE 替代品相比，填充 EPR 配方显示出优异的抗水树枝性能，使其特别适合恶劣的 (N)TSCGEWÖU 操作环境。根据 IEEE 400.2 指南进行定期 tan delta 监测，结合趋势分析和互补 PD 测试，能够实现有效的预测性维护策略，优化电缆资产生命周期管理并最大限度地减少计划外停运。

English: Anhui Feichun Special Cable Co., Ltd specializes in manufacturing high-performance (N)TSCGEWÖU cables meeting international standards including IEC, DIN VDE, and ICEA specifications. Our 3GI3 EPR formulations are engineered for maximum service life in submersible, mining, and heavy industrial applications where cable reliability is mission-critical.

中文：安徽飞纯特种电缆有限公司专业制造符合 IEC、DIN VDE 和 ICEA 规范等国际标准的高性能 (N)TSCGEWÖU 电缆。我们的 3GI3 EPR 配方专为在电缆可靠性至关重要的可浸没、采矿和重工业应用中实现最长使用寿命而设计。