The core purpose of testing the dielectric loss (dielectric loss factor) and volume resistivity of insulating oil is to evaluate whether the insulating performance of the insulating oil is qualified, which is directly related to the safe and stable operation of power equipment such as transformers.
1. Reasons for Testing Dielectric Loss
Dielectric loss reflects the energy loss of insulating oil caused by polarization and leakage current under the action of an electric field, and it is a key indicator for judging oil aging and contamination.
• Judging oil aging: Insulating oil will oxidize and decompose to produce acidic substances and impurities after long-term use, leading to an increase in dielectric loss value, which indicates a decline in the insulating performance of the oil.
• Detecting contamination degree: If the oil is mixed with impurities such as moisture, metal particles, and dust, the dielectric loss will increase significantly, which may cause partial discharge or even breakdown, threatening the safety of the equipment.
2. Reasons for Testing Volume Resistivity
Volume resistivity represents the ability of insulating oil to prevent current from passing through, and directly reflects its insulation strength.
• Evaluating insulation capacity: The higher the resistivity, the stronger the insulating performance of the oil; a decrease in resistivity means an increase in the conductivity of the oil, which may easily lead to equipment insulation failure, leakage, or short circuit.
• Assisting in judging oil condition: Moisture, impurities, and aging products will significantly reduce the resistivity. Combining with dielectric loss data can help to more comprehensively grasp the deterioration of oil quality and avoid sudden equipment failures.
