(1) An iron yoke clamp grounding lead shall be set separately. Because if the iron core touches the upper clamp, resulting in multi-point grounding fault, the grounding current only flows inside the iron core clamp, and there is no current in the iron core grounding outgoing line, which will lead to the staff mistakenly believing that the iron core has not failed; After setting, no matter where the iron core touches the clamp, it will form a loop through two external grounding leads, so that the grounding current can be correctly detected externally.

(2) The iron core grounding strip is placed in the middle of the cross section of the yoke. In this way, no matter where the insulating bolt of the iron yoke strap is and where the fault grounding point is, the best induced voltage of the circuit is only 1 / 4 of the turn voltage, and the ZD grounding current is only about a few amps, which is much smaller than when the iron core grounding strip is placed in other positions.

(3) If it is really necessary to place the iron core grounding strip at other positions due to inconvenient on-site installation, the insulating bolt and grounding strip of the iron yoke strap shall also be placed diagonally, so as to prevent large current.