When the power transformer is in normal operation, the dəmir əsas must be reliably grounded at one point. If there is no grounding, the floating voltage of the iron əsas to the ground will cause intermittent breakdown and discharge of the iron core to the ground. After the iron core is grounded at one point, the possibility of forming the floating potential of the iron core is eliminated. However, when the iron core is grounded at more than two points, the uneven potential between the iron cores will form a circulation between the grounding points, and cause the multi-point grounding of the iron core to generate heat.

The grounding fault of the iron core of the transformer will cause partial overheating of the iron core. In severe cases, the local temperature rise of the iron core will increase, light gas will operate, and even cause a trip accident due to heavy gas operation. The melted local iron core forms a short-circuit fault between the iron chips, which increases the iron loss and seriously affects the performance and normal operation of the transformer, so that the silicon steel sheet of the iron core must be replaced for repair. Therefore, the transformer does not allow multi-point grounding and can only have one and only one point grounding.