The principal cause of lightning stroke failures occurred in UHV transmission lines is the shielding failure, so it is suggested to adopt the negative protectingAngle for UHVDC transmission lines.
引起特高压输电线路雷击故障的主要因素是雷电绕击，建议特高压输电线路采用负保护角运行。
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This thesis is concerned about the handicapped from the Angle of employment, and is on the purpose of protecting the handicapped form an active way by advancing their abilities of self-security.
When the linear length of the protecting pipe is over 30m, the junction box should be added; and when there are more than 2 right-angle bends, junction box should be added between them.