When measuring transformer insulation, attention should be paid to the following issues:
1. It must be carried out during the power outage of the transformer, and there are obvious disconnection points for each coil outlet.
2. The surrounding area of the transformer is clean and free of any grounding objects.
3. Before measurement, discharge to the ground, and after measurement, discharge to the ground as well.
4. The shake table used for measurement should meet the voltage level requirements.
5. For transformers with neutral grounding, the neutral switch should be opened before measurement and restored to its original position after measurement.