Warning Signs of Faulty Distribution Transformers in Summer High Temperature
Summer high temperatures bring a peak failure period for power distribution equipment, especially for oil immersed distribution transformer. Many power system operators rely solely on comprehensive protection devices to judge transformer operating conditions. However, conventional protection systems only respond to catastrophic faults and cannot detect sub-health operating states in advance. To avoid sudden shutdowns and safety accidents, it is essential to identify four early warning signals of transformer failures.
Firstly, check the three-phase operating current. Operators need to compare the real-time current value with the rated current on the transformer nameplate. Exceeding the rated current directly indicates overload operation, which is a common issue for oil immersed distribution transformer under summer heavy load conditions. In addition, excessive current imbalance among three phases usually points to unbalanced load distribution or potential internal winding faults, which will gradually damage the transformer insulation system over time.
Secondly, monitor the secondary side voltage. Under normal grid conditions, if the secondary voltage drops significantly from the standard 400V to 380V or even 370V, it is not caused by grid fluctuation in most cases. This obvious voltage drop is a typical warning sign of long-term overload of the oil type distribution transformer, which will reduce power supply quality and accelerate equipment aging.
Thirdly, track the operating temperature strictly. Temperature is the most intuitive indicator of transformer health. For oil-immersed transformers, the safe operating temperature should not exceed 85°C. Once the temperature approaches 95°C, operators must reduce the load immediately to prevent internal insulation aging and oil deterioration. Continuous high temperature operation is the main cause of shortened service life of distribution transformers in summer.
Lastly, distinguish abnormal operating noise. A normally running transformer emits a uniform low humming sound. If unusual sizzling or crackling sounds appear, it indicates internal partial discharge faults. A boiling water-like bubbling noise means severe internal thermal faults, which may lead to oil injection or even explosion. In this case, power cutoff and isolation treatment must be carried out immediately.
At Zhejiang Hengli Electrical, we insist that professional transformer operation and maintenance focuses on early prevention rather than emergency repair. Mastering these four practical detection methods helps eliminate hidden dangers before protection devices trigger, ensuring stable and safe operation of all oil-immersed distribution transformers in high-temperature summer environments.
