As an important insulating and cooling medium, the quality of transformer oil is directly related to the safe and stable operation of transformer. Therefore, it is far from enough to judge the deterioration of transformer oil only by the voltage and resistance of the damage test. It also determines the density, viscosity, flash point, acid value, volume resistivity, water content, oil color and surface tension to judge the deterioration of transformer oil and take corresponding measures.
Specific analysis is as follows:
1. Density: Transformer oil density is generally below 0.92, which is related to temperature and is 0.89 at 20 C. After operation, the purity of transformer oil is determined by comparing with the new oil density value.
2. Flash point: According to the state regulations, the flash point of transformer oil shall not be less than 135 C.
3. Viscosity: Different types of transformer oil have different viscosities. China stipulates that the viscosity should not be greater than 9.4 x 10-6 m2/s at 50 C. Viscosity should not be greater than 5.5 *10-6m2/s at 75 ~C
4. 酸价:按变压器油国家标准，酸价不得大于0.051mgkoh /g。当酸值小于或等于0.2mgKOH/g时，油泥几乎不可能产生。油泥产量可达0.4mg /g。当油泥超过0.4mgkoh /g时，油泥会非常大。应及时进行油处理或变压器换油。
4. Acid value: According to the national standard of transformer oil, the acid value should not exceed 0.051 mg koh/g. When the acid value is less than or equal to 0.2 mg KOH/g, it is almost impossible to produce sludge. The sludge yield can reach 0.4 mg/g. When the sludge exceeds 0.4 mg koh/g, the sludge will be very large. Oil treatment or transformer oil change should be carried out in time.
5. 变压器油绝缘击穿:耐压试验装置中变压器油绝缘间隔为2.5mm, 35kv以上设备绝缘击穿值为40kv。击穿电压值越高，变压器油的绝缘性能越好。
5. Insulation breakdown of transformer oil: Insulation interval of transformer oil is 2.5 mm in voltage withstanding test device, and the insulation breakdown value of equipment above 35 kV is 40 kv. The higher the breakdown voltage, the better the insulation performance of transformer oil.
6、油体积电阻率(Ω·厘米):一般体积电阻率应大于3.0 x 1012Ω厘米,体积电阻率和变压器绝缘等级有直接关系。
6. Oil Volume Resistivity (_. cm): General Volume Resistivity should be greater than 3.0 x 1012_cm. Volume Resistivity is directly related to transformer insulation grade.
7. Oil Moisture Content (PPM): With the increase of oil moisture content, the breakdown voltage of oil insulation will also decrease. Reducing water content in oil products is one of the most effective means to improve the insulation performance of transformer oil products.
8. Oil color: Transformer oil is transparent liquid, if it deteriorates to brown.
9. Surface tension: The degree of deterioration of oil can be directly determined by surface tension. In the initial stage of oil oxidation, the surface tension began to decrease, the oxidation speed increased, and the surface tension decreased more seriously.
变压器的操作、取样和测试35 kv变压器进行每年至少一次,和变形金刚的取样和测试35 kv以下每三年至少进行一次,以掌握变压器油的变化趋势,及时采取相应措施,确保变压器的正常运行。
The operation, sampling and testing of 35 kV transformer shall be carried out at least once a year, and the sampling and testing of transformer diamond shall be carried out at least once every three years below 35 kV in order to grasp the changing trend of transformer oil and take corresponding measures in time to ensure the normal operation of transformer.