The zero-sequence protection device of the substation and the open-close station line adopts more and more open zero sequence current transformer. It should be installed on the bottom of the switch cabinet and should be fixed by a reliable bracket. After the cable termination head passes through the external open zero sequence current transformer, the metal sheath at the terminal of the three-core power cable must be well grounded; the copper shield of each phase of the plastic cable and the steel wire should be soldered to the ground wire, and the cable passes through the zero-sequence current mutual inductance. When the device is used, the cable metal sheath and the grounding wire should be insulated from the ground. When the cable grounding point is below the transformer, the grounding wire should be grounded directly.
When the grounding point is above the transformer, the grounding wire should pass through the transformer grounding. The grounding wire must be connected to the special grounding copper bar in the switchgear. The grounding wire must be copper stranded wire or tinned copper braided wire. The cross section of the grounding wire must be Meet the requirements of the regulations. It should be ensured that the inner diameter of the zero-sequence current transformer is greater than the outer diameter of the cable terminal.
During construction, try not to dismantle the open zero sequence current transformer. If it must be dismantled, the work must be restored to its original state; the grounding wire must be copper-stranded or tinned copper braided wire. The cross-section of the grounding wire should not be less than 25 mm2. The terminal should solder the terminal block and correctly handle the relative position of the grounding wire and the zero-sequence current transformer. The grounding wire must be installed on the grounding copper bar. Before power-on, the zero-sequence protection system should be adjusted to ensure normal protection.www.ctsensorducer.com