零序电流互感器与接地线的关系应掌握一个原则：电缆两端端部接地线与电缆金属保护层、大地形成的闭合回路不得与零序电流互感器匝链（穿过）。
The relationship between zero-sequence current transformer and grounding wire should be based on one principle: the grounding wire at both ends of the cable and the metal protective layer of the cable, and the closed loop formed by the earth should not be linked to the zero-sequence current transformer (through).
即当电缆接地点在零序电流互感器以下时，接地线应直接接地；接地点在零序电流互感器以上时，接地线应穿过零序电流互感器接地。
That is, when the grounding point of the cable is below the zero-sequence current transformer, the grounding line should be directly grounded; when the grounding point is above the zero-sequence current transformer, the grounding line should be grounded through the zero-sequence current transformer.
同时，由电缆头至零序电流互感器的一段电缆金属护层和接地线应对地绝缘，对地绝缘电阻值应不低于50kΩ。以上做法是为了防止电缆接地时的零序电流在零序电流互感器前面泄漏，造成误判断；经电缆金属护层流动的杂散电流由接地线流入大地，也不与零序电流互感器匝链，杂散电流也不会影响正确判断。
At the same time, the metal shield and ground wire of a section of cable from the cable head to the zero sequence current transformer should be insulated to the ground, and the insulation resistance should not be less than 50 K. The above method is to prevent the leakage of zero-sequence current in front of the zero-sequence current transformer when the cable is grounded, resulting in misjudgment; stray current flowing through the cable metal sheath flows from the grounding line to the ground, and does not turn the chain with the zero-sequence current transformer, stray current will not affect the correct judgment.