In order to analyze the temperature distribution of circuit breaker tulip contact, a thermal field simulation model for tulip contact is built combined with the electromagnetic-stress-thermal coupled finite element simulation and virtual material method which models the contact resistance characteristics of tulip contact. The temperature rise characteristic of tulip contacts under rated current conditions and short-circuit conditions is analyzed with the model. Results show that the virtual material method can describe the contraction resistance and additional resistance at the end of the contact finger simultaneously, so as to simulate the partial high temperature of the contact interface. Then, the influence of spring pressure and pressure uniformity on the thermal field of tulip contact is analyzed. Results show that the decrease of spring pressure and the imbalance of contact finger pressure may lead to an increase in the temperature rise of the tulip contact. The proposed method can be used as a reference for the design and the overheating analysis of tulip contact.

The impulse grounding impedance of tower grounding device is one of the important factors in the lightning protection evaluation of transmission line. The impulse characteristic test of the actual tower grounding device under lightning was rarely carried out due to the limitation of the test conditions. With the help of Guangzhou Field Experiment Site for Lightning Research and Testing, the artificial lightning characteristic test of the true tower grounding device was carried out. This paper presented partial observation experimental results and related analysis of the impulse grounding impedance of tower grounding device subjected to artificial lightning M‐component. A calculation model of the tower grounding device subjected to lightning M‐component was established. The changes of the surface soil resistivity under the action of rainwater were taken into account in the calculation. The test data and calculation results of the tower grounding device under the impact of the artificial lightning M‐component had achieved good agreement. The non‐linear ionization of the soil around the tower grounding device can be ignored, and the real impulse grounding impedance was very close to the DC grounding resistance or power frequency grounding impedance, when the tower grounding device in the experiment was subjected to lightning current M‐component.