The Impact of Impurities on Insulating Oil Breakdown Voltage and Its Associated Risks
Insulating oil is a critical component in transformers and high-voltage equipment, serving both as an insulating medium and a cooling agent. The breakdown voltage (BDV) is a key parameter used to evaluate the insulating performance of the oil. BDV refers to the minimum voltage at which the insulating oil loses its dielectric strength and undergoes electrical breakdown. A higher BDV indicates good insulating performance, while a low BDV suggests significant contamination, posing a threat to equipment safety and reliability.
Effects of Impurities on BDV
Even a small amount of impurities in insulating oil can significantly reduce its breakdown voltage. In transformer oil, common impurities include air bubbles, moisture, and fiber particles.
Impact of Air Bubbles
The dielectric constant of transformer oil is more than twice that of air, and the electric field strength is inversely proportional to the dielectric constant. When air bubbles are present in the oil, the electric field intensity around the bubbles increases due to field distortion. Moreover, the dielectric strength of air is much lower than that of oil, making the air bubbles more prone to ionization. Ionization generates charged particles that collide with oil molecules, causing further gas decomposition. This chain reaction leads to an accelerated increase in gas content, eventually aligning bubbles along the electric field and causing electrical breakdown.
Impact of Moisture and Fiber Contaminants
Moisture, particularly when absorbed by fiber contaminants such as cotton yarn or paper, has a severe impact on the insulating strength of the oil. Due to its high dielectric constant, moisture can concentrate electric field strength and induce localized discharges. Water-laden fibers under an electric field can form conductive pathways, drastically lowering the oil's insulation performance and increasing the risk of breakdown.
Risks Associated with Low BDV
Equipment Damage
Oil breakdown can result in internal short circuits or insulation failure within the transformer, leading to damage to critical components like windings and cores, and in severe cases, explosions.
Power System Disruption
Breakdown incidents can cause transformer outages, leading to interruptions in power system operations, widespread impacts, and significant economic losses.
Latent Safety Hazards
Operating equipment with low BDV increases the likelihood of partial discharges or overheating, which may accumulate into catastrophic faults, endangering nearby infrastructure and personnel.
Measures to Improve BDV
Strict Oil Treatment
Regular vacuum degassing and filtration of insulating oil to reduce the content of air bubbles, moisture, and solid particles.
Online Monitoring
Utilize online oil monitoring systems to track changes in BDV in real-time, enabling early detection and resolution of potential issues.
Maintenance of Equipment
Perform routine cleaning and drying of internal insulating components in transformers to prevent fiber impurities from entering the oil.
Conclusion
The breakdown voltage of insulating oil is a vital parameter for ensuring the stable operation of power equipment. Although the impurities in oil may seem negligible, their potential to trigger chain reactions poses a significant threat. By rigorously managing oil quality, optimizing equipment maintenance, and employing advanced monitoring techniques, the breakdown voltage of insulating oil can be effectively enhanced, ensuring the safety and efficiency of electrical equipment operations.
Transformer Insulating oil breakdown voltage tester JY6611
