(1) 零序电流互感器应装在开关柜底板上面，应有可靠的支架固定。但有些厂家或施工单位将零序电流互感器安装在开关柜底板下面的支架上，更有甚者将零序电流互感器捆绑在电缆上，这违背了开关柜全封闭原则，既不安全，也不防尘，更不防小动物，留下很多隐患。

(1) the zero sequence current transformer should be installed on the bottom board of the switch cabinet, and it should be supported by a reliable bracket. But some manufacturers or construction units will support the zero sequence current transformer is installed below the bottom of the switch cabinet, even the zero sequence current transformer bundled on the cable, which is contrary to the principle of fully enclosed switchgear, neither safe nor dust, but not prevent the small animal, a lot of problems left behind.

(2) 电缆终端头穿过外附零序电流互感器后，电缆金属屏蔽接地线与外附零序电流互感器的相对位置不正确。根据有关规定：三芯电力电缆终端处的金属护层必须接地良好；塑料电缆每相铜屏蔽和钢铠应锡焊接地线(油浸纸绝缘电缆铅包和铠装应焊接地线)，电缆通过零序电流互感器时，电缆金属护层和接地线应对地绝缘，电缆接地点(电缆接地线与电缆金属屏蔽的焊点)在互感器以下时，接地线应直接接地；

(2) after the cable terminal head passes through the zero sequence current transformer attached outside, the relative position of the metal shielded earth wire of the cable and the external zero sequence current transformer is not correct. According to the relevant provisions: three core power cable terminal metal shield must be well grounded in each phase; plastic cable and copper shielding steel cayin tin welding wire (oil paper insulated cable lead packages and welding wire, cable should be shielded) through the zero sequence current transformer, cable metal sheath and grounding wire to ground insulation cable, ground (joint cable metal shield wire and cable) in the transformer when the grounding wire should be directly grounded;

接地点在互感器以上时，接地线应穿过互感器接地，接地线必须接在开关柜内专用接地铜排上，接地线须采用铜绞线或镀锡铜编织线，接地线的截面必须符合规程要求。在检查中发现有些电缆接地线该穿零序电流互感器时未穿，一些不该穿零序电流互感器的反倒穿了，造成事故接地零序保护不能正确动作。

Take place in the transformer when the grounding wire should be through transformer grounding, grounding wire must be connected to the switch cabinet for ground copper bars, the grounding wire should be used in copper wire or tinned copper braided wire, grounding wire section must meet the requirements in the specification. In the inspection found that some cable ground wire, when the zero sequence current transformer is not worn, and some should not wear zero sequence current transformer instead of wearing, causing the accident ground zero sequence protection can not correct action.