Why does one end of the cable grounding wire go through the zero sequence CT, while the other end is

Because the value of the three-phase current when grounded is the zero-sequence current, and this zero-sequence current will pass through the grounding line to form a path, the zero-sequence CT senses the magnetic field generated by the current flow, if the grounding line does not go through the middle of the zero-sequence CT, the zero-sequence CT will have no way to sense, so there is no current; there is also a case, some friends say that when my CT set in the cable head above the part, then my grounding line Is not from the bottom to the top through out? Also can not be, because, as mentioned above, non-three grounding, there is a zero sequence current flow, stripped cable shielding is not grounded, zero sequence CT directly set in the stripped three-phase cable, the same can be induced current vector and (i.e., the zero sequence current) flux can be accurately do a good job of zero-sequence protection, do not be in the zero sequence CT set in the cable above the position, the ground wire from the bottom to the top of the cable head, the ground wire from the bottom to the top of the zero sequence CT through the internal and then wear down from the outside to ground. In addition, the ground wire from the cable head to the zero sequence CT through the whole section must be good insulation measures to prevent the CT before touching the cabinet grounding and loss of zero sequence protection.