Grounding Requirements for Transformer Cores

1. Set up an independent grounding lead for the core yoke clamp.
If the core touches the upper clamp and causes a multi-point grounding fault, the grounding current will only circulate inside the core clamp, and no current will flow through the main core grounding lead. This may lead personnel to mistakenly believe that the core has not malfunctioned. By setting up this independent lead, no matter where the core touches the clamp, a loop will be formed through the two external grounding leads. In this way, the grounding current can be accurately detected externally.

2. Place the core grounding tab at the center of the yoke's cross-section.
With this placement, regardless of the position of the yoke strap's insulating bolt and the location of the fault grounding point, the maximum induced voltage in the loop is only 1/4 of the turn voltage. At this time, the maximum grounding current is only about a few amperes, which is much smaller than when the core grounding tab is placed in other positions. (注：原文的“好多个伏特”结合上下文应为电流单位“安培”，已帮你修正为 amperes)

3. If it is indeed necessary to place the core grounding tab in another position due to on-site installation constraints, the insulating bolt of the yoke strap and the grounding tab should be placed diagonally opposite to each other.