How to measure the Earth Resistance of dry-type transformer?

How to measure the Earth Resistance of dry-type transformer? It is believed that most non-professionals are unfamiliar with this, the rural distribution transformer grounding resistance is often ignored or not, but it is related to the safe operation of transformers. In general, the smaller the grounding resistance is, the better, therefore requires 100 KVA and above transformer grounding resistance should not be more than 4 euro, 100 Kva less than the transformer should not be more than 10 euro, but because the grounding pole long-term buried in the ground, easy to soil erosion and damage, so that the grounding resistance increases, so the transformer grounding resistance should be measured regularly.

Dry-type transformer ground resistance, dry-type transformer resistance measurement, dry-type transformer ground resistance measurement preparation 1. It should be carried out in dry weather. 2. Before measurement, after taking necessary safety measures, disconnect the connection point between the transformer and the ground electrode. 3. Insert two earthing pins of length not less than 500 mm into the ground, so that they are not less than 400 mm deep, and try to keep the earthing pole and the two earthing pins on the same line, and the distance between them is 20 m, then, the three terminal buttons E, P and C of the insulation resistance meter are connected to the grounding electrode of the transformer and two grounding pins respectively with special wires. The P point is required to be between the other grounding pin and the grounding electrode of the transformer. Dry-type Transformer Ground Resistance Measurement 1. Place the insulation resistance meter horizontally and adjust the zero knob of the swing meter so that the meter needle is at zero position. 2. According to the grounding resistance required by the transformer and the actual situation on the spot, put the multiplier switch on the proper gear and start slowly shaking the insulation resistance meter. At the same time, turn the dial of the potentiometer so that the pointer is on the zero position and then speed up, and at 120 RPM and adjust the potentiometer KNOB, so that the pointer stable at zero, at this point with the dial reading times the multiplier is the transformer grounding resistance value. 3. When the measured value is greater than the requirements, should find out the reasons, and as soon as possible to resolve to make it meet the requirements. 4. When the measured value is less than 1 euro, in order to eliminate the influence of the connection resistance and contact resistance, the connecting plates of the two terminal buttons on the insulation resistance meter should be opened. There is also a dedicated grounding resistance measuring instrument