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<p>The thermal performance of dry-air-insulated switchgear is fundamentally constrained by the low volumetric heat capacity of dry air, making electrical contact degradation a primary driver of thermal risk. This work develops a three-dimensional electro-thermal fluid multiphysics model for a 12&#xa0;kV/3150 A dry-air-insulated switchgear, incorporating a thermo-mechanically coupled dynamic contact resistance model that captures the temperature-dependent reduction in contact pressure—a coupling mechanism typically excluded in conventional thermal analyses. The model is calibrated against a single high-current (3465 A) temperature rise test, yielding a maximum simulation deviation of 2.55&#xa0;K across all measurement points. The analysis reveals that the conventional constant-resistance approach systematically underestimates thermal escalation under contact faults. When simulating circuit breaker contact degradation, the dynamic model predicts a steady-state temperature rise that is 21.6% higher (107&#xa0;K vs. 88&#xa0;K) and an initial heating rate that is 33% faster than the constant-resistance case. Under coupled multi-contact faults, the hotspot temperature rise reaches 156&#xa0;K—a 45.8% increase over the single-fault case—confirming a nonlinear thermal synergy effect. The circuit breaker contacts are identified as the dominant thermal bottleneck, exhibiting a temperature rise 1.6 times greater than that of the upper busbar under normal conditions, and remaining the most vulnerable region across all fault scenarios. These findings provide a quantitative basis for improving thermal management design and transitioning from time-based to condition-based maintenance strategies for dry-air-insulated switchgear.</p>

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Multiphysics simulation of thermal performance in dry-air-insulated switchgear: impact of dynamic contact resistance

  • 期刊论文

  • 发表日期：

    2026年7月14日

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  • Xiaogang Zheng,
  • Richang Xian,
  • Rujie Zhao,
  • Junhao Guo,
  • Yuyao Hu

摘要

The thermal performance of dry-air-insulated switchgear is fundamentally constrained by the low volumetric heat capacity of dry air, making electrical contact degradation a primary driver of thermal risk. This work develops a three-dimensional electro-thermal fluid multiphysics model for a 12 kV/3150 A dry-air-insulated switchgear, incorporating a thermo-mechanically coupled dynamic contact resistance model that captures the temperature-dependent reduction in contact pressure—a coupling mechanism typically excluded in conventional thermal analyses. The model is calibrated against a single high-current (3465 A) temperature rise test, yielding a maximum simulation deviation of 2.55 K across all measurement points. The analysis reveals that the conventional constant-resistance approach systematically underestimates thermal escalation under contact faults. When simulating circuit breaker contact degradation, the dynamic model predicts a steady-state temperature rise that is 21.6% higher (107 K vs. 88 K) and an initial heating rate that is 33% faster than the constant-resistance case. Under coupled multi-contact faults, the hotspot temperature rise reaches 156 K—a 45.8% increase over the single-fault case—confirming a nonlinear thermal synergy effect. The circuit breaker contacts are identified as the dominant thermal bottleneck, exhibiting a temperature rise 1.6 times greater than that of the upper busbar under normal conditions, and remaining the most vulnerable region across all fault scenarios. These findings provide a quantitative basis for improving thermal management design and transitioning from time-based to condition-based maintenance strategies for dry-air-insulated switchgear.