How is transformer oil resistivity measured?

Transformer oil resistivity is measured using a resistivity meter, which applies a voltage across two electrodes submerged in the oil sample. The resulting current flow is used to calculate resistivity, typically expressed in ohm-meters. Measurements are conducted at a controlled temperature, as resistivity is temperature-dependent. Proper sample preparation and electrode spacing are crucial to ensure accurate and consistent results, reflecting the oil’s insulating properties and overall quality.