Herein, a three-dimensional (3D) finite element model of a strain clamp-conductor system is established, with an NY-300/40 compression-type strain clamp taken as an example. The tensile load-carrying capacity of the strain clamp under standard crimping conditions is analyzed with LS-DYNA software, and the simulation results are compared with the experimental results to verify the accuracy of the model. On this basis, the tensile load-bearing capacity and failure mode of the strain clamp-conductor system are analyzed when the crimping length between the steel anchor and steel core is insufficient. Studies have shown that the grip strength of a strain clamp is provided mainly by the crimping between the steel anchor and the steel core. Under standard crimping conditions, the tensile load-bearing capacity of the strain clamp can meet the design requirements. Moreover, because the crimping length between the steel anchor and steel core is sufficient, the strain clamp fails due to aluminum strand breakage rather than the steel core being pulled out of the steel anchor. When the crimping length is insufficient, the grip strength of the strain clamp decreases with decreasing crimping length. Although the absolute value of the grip strength does not decrease significantly, the failure mode gradually changes from the breakage of the aluminum strands to the steel core being pulled out of the steel anchor. For the NY-300/40 compression-type strain clamp, the corresponding critical crimping length (i.e., when the change in failure modes occurs) between the steel core and the steel anchor is 50∼60 mm.

Based on an actual ultra-high voltage (UHV) substation, a finite element (FE) model for a high-voltage (HV) bushing, arrester, and down lead transmission line (DLTL) system was built using ANSYS software. The dynamic responses of the system under different seismic intensities were analyzed and compared with those of the corresponding single bushing and arrester. On this basis, the coupling vibration influence of the upper DLTL on the responses of the HV bushing and arrester is discussed. The results indicate that the DLTL adversely affects the responses of the HV bushing and arrester under seismic loading. As the seismic intensity increases, the structural displacements at the top of the HV bushing and arrester increase, accompanied by a reduction in the geometric length redundancy of the DLTL, resulting in a mutual pulling effect between the HV bushing and the arrester and the quick amplification of their respective dynamic responses in a nonlinear form. Under the action of an earthquake with a peak ground acceleration (PGA) of 0.4 g, the maximum stresses at the roots of the HV bushing and the arrester in the system separately increase by approximately 13.02% and 7.80% compared to the corresponding single HV bushing and the arrester. Overall, a geometric length redundancy of at least 200 mm in the DLTL in engineering design is recommended.