电缆接地箱的应用
Application of cable grounding box
对于高压单芯电缆系统，应根据实际情况采用合适的电缆护套接地方式。工程应用中对短电缆一般采用金属护套一端接地，另一端经护层保护器接地的方式；对长电缆线路，一般采用电缆护套交叉互联的接线方式。当雷电波或操作波沿线芯流动时，电缆接头金属屏蔽层不接地端将出现过电压，易使护套产生绝缘损坏形成多点接地，出现很大的环形感应电流。为此，应在电缆接头处金属护套不接地点加装电缆护层保护器。 为防止电缆外护套绝缘在单相短路情况下加速老化，长电缆线路宜采用完全交叉互联的保护方式。金属屏蔽层采用混合连接方式时，应在单点接地保护方式电缆段加装回流线路合理地选择该段电缆的长度。
For high-voltage single core cable system, appropriate cable sheath grounding mode should be adopted according to the actual situation. In engineering application, one end of the metal sheath is grounded for the short cable, and the other end is grounded by the sheath protector; for the long cable line, the cross interconnection of the cable sheath is generally adopted. When the lightning wave or operation wave flows along the core, overvoltage will appear at the ungrounded end of the metal shielding layer of the cable joint, which is easy to cause insulation damage of the sheath and form multi-point grounding, resulting in large ring induced current. Therefore, the cable sheath protector should be installed at the point where the metal sheath is not grounded at the cable joint. In order to prevent the accelerated aging of cable sheath insulation under single-phase short circuit, the complete cross interconnection protection mode should be adopted for long cable lines. When the metal shielding layer adopts the mixed connection mode, the return line should be installed in the single point grounding protection cable section, and the length of the cable section should be reasonably selected.