## 5 The Influence of the down Conductor on the Lower Electrical Equipment
### Mechanical Properties of a Soft Bus
#### 5.1.2 Flexible Bus Bars with Different Connection Forms  
EEE 1527 proposes four types of soft bus connections: reverse parabolic connection C1, hyperbolic connection C2, overhanging connection C3, and three-curve connection C4. Different flexible bus connection forms have their own characteristics. The C1-type connection is more suitable for connecting equipment with a large relative displacement; however, because it is easily affected by external loads such as icing during use and becomes unstable and deforms into a C3-type connection, it is not suitable for a large connection span. The C2 connection is very suitable for the situation where one end connection must be horizontal. This type of connection is not affected by the span but may have a large overhang, which affects the safety clearance. The C3 connection is the simplest form of the four methods, and the disadvantage is also obvious; that is, it does not easily meet the requirement for a safe clear distance between the equipment and the bus bar, and the bus bar and the ground. The safety clearance problem is easier to meet with the C4-type connection, and the slack is greater than that of the C3-type connection when the drap is the same. Studies [27] have shown that when the degree of relaxation is the same for the four types of soft bus bars, then the end force of the C4 connection increases the fastest, while the end force of the C3 connection increases the slowest. 1.3 Analysis of the Response of a High-Voltage Casing and a Single Structure Lightning Arrester under Different Seismic Peak Accelerations  
To study the influence of down conductors on lower electrical equipment, seismic wave input is now performed on the high-voltage bashing and the single structure of the arrester. According to the previous chapter, the vertical vibration response of the lead system is very small compared to other directions regardless of the working condition of the lead system, and the vibration response of the structure is slightly larger when the seismic wave is input from three directions rather than one direction. Considering that the main purpose of this chapter is to study the influence of down conductors on the system, the vertical input is ignored when the seismic wave input is performed for the high-voltage bashing and arrester unit, only three-way input is used, and the vibration response of the unit is the same as the PGA. The following lead systems are compared (as shown in Tables 5 and 6). \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **PGA** & \begin{tabular}{c} **X-Direction Displacement** \\ **Increase the Percentage** \\ \end{tabular} & \
\begin{tabular}{c} **Z-Direction Displacement** \\ **Increase the Percentage** \\ \end{tabular} &
\begin{tabular}{c} **Stress Increase** \\ **Percentage** \\ \end{tabular} \\ \hline \multirow{5}{*}{EL wave} & 0.035 g & 0.38 & 0.15 & 0.20 \\  & 0.1 g & 1.63 & 0.81 & 0.86 \\  & 0.22 g & 5.38 & 2.62 & 2.81 \\  & 0.07 g & 0.90 & 0.45 & 0.48 \\  & 0.2 g & 4.46 & 2.25 & 2.35 \\  & 0.4 g & 28.13 & 8.11 & 13.02 \\ \hline \multirow{5}{*}{Taft wave} & 0.035 g & 0.35 & 0.13 & 0.18 \\  & 0.1 g & 1.41 & 0.41 & 0.42 \\ \cline{1-1}  & 0.22 g & 4.76 & 2.45 & 2.52 \\ \cline{1-1}  & 0.07 g & 0.79 & 0.75 & 0.76 \\ \cline{1-1}  & 0.2 g & 3.92 & 2.05 & 2.08 \\ \cline{1-1}  & 0.4 g & 24.03 & 7.53 & 11.11 \\ \hline \multirow{5}{*}{Artificial wave} & 0.035 g & 0.37 & 0.15 & 0.19 \\  & 0.1 g & 1.48 & 0.79 & 0.80 \\ \cline{1-1}  & 0.22 g & 5.02 & 2.51 & 2.63 \\ \cline{1-1}  & 0.07 g & 0.88 & 0.44 & 0.46 \\ \cline{1-1}  & 0.2 g & 4.12 & 2.15 & 2.20 \\ \cline{1-1}  & 0.4 g & 27.16 & 7.53 & 12.49 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Comparison of the seismic dynamic response of the single high-voltage casing and the overall model. The comparison charts of the stress and the displacement amplification ratio of the high-voltage pushing and the lightning arrester are shown in Figures 22 and 23. When the PGA is small, the down-lead redundancy is sufficient and it has little impact on the lower electrical equipment.