Discussion on Causes and Preventive Measures of Oil Leakage Power Transformer Oil Leakage

2019-06-29 14:34:31 JuKe Technology (DongGuan) Co., Ltd. Read

Discussion on Causes and Preventive Measures of Oil Leakage Power Transformer Oil Leakage

In the event of a fault in an oil-immersed Power Transformer, a power interruption will occur, causing immeasurable losses. Therefore, it is very important to do a good job in maintenance and management of transformers. Over the years, Juke Industry, a power transformer manufacturer, has accumulated some reasons for the leakage of transformer oil and its control measures. It has played an important role in analyzing and discussing the damage and control of transformer oil leakage.
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1 Oil immersed power transformer oil leakage damage to the main equipment

1.1 Transformer oil leakage is mainly divided into gas leakage and oil leakage.

(1) Gas leakage means that the gas part inside the transformer is connected to the atmosphere, and the gas leakage is a macroscopic invisible leakage, such as a gas relay joint, a cooler heat pipe, a casing head, and a capsule of a oil storage cabinet. The air in and out of other parts leaks. Moisture and oxygen in the air will slowly penetrate into the transformer through the leakage point, and the seal inside and outside the transformer will be destroyed, resulting in insulation moisture and accelerated deterioration of oil quality.

(2) Oil leakage, leakage when the oil pressure at the leak is less than or equal to the oil liquid leakage pressure. Including internal leakage, external leakage. Internal leakage refers to leakage of oil in the casing or oil in the on-load tap-changer chamber to the transformer body; external leakage refers to leakage of the weld and leakage of the seal.

Both types of leakage are mutually leaking processes, so that the internal insulation is no longer isolated from the atmosphere, which destroys the internal insulation until the main insulation strength drops significantly, and even the insulation loses its effect. Directly endangers the stable operation of the transformer.

1.2 Hazards of Oil Leakage Power Transformer Oil Leakage

The hazards of transformer oil leakage are mainly manifested in several aspects:

(1) The transformer in operation, where there is oil leakage, it is easy to attach a large amount of dust, so that the outer surface of the equipment is contaminated with oil, one of which affects the heat dissipation effect, especially the cooler, and the other is the influence of the inspection and observation equipment. It is greatly affecting the beauty of the equipment.

(2) Leakage of transformer oil will accelerate the transition of the transformer from a sealed state to an unsealed state, which will accelerate the aging of the transformer oil. In severe cases, the insulation will be damp, causing a short-circuit of the transformer and a power outage.

(3) Severe oil leakage, wasting oil resources and polluting the scene environment.

(4) Severe oil leakage will reduce the oil level of the transformer, causing the live joint and the on-load tap-changer transformer coil to operate under the condition of no oil insulation. In severe cases, some transformer coils will be exposed, resulting in insulation breakdown and short circuit. .
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2 The main cause of oil leakage in oil-immersed power transformers

Through years of maintenance and overhaul of three main transformers, we have accumulated some work experience in oil-immersed transformer oil treatment, which causes the leakage of transformer oil to have the following aspects:

(1) The sealing pad is aged and cracked. The leakage of the transformer mostly occurs at the sealing gasket, mainly due to the aging crack of the gasket. The quality of the sealing pad mainly depends on its oil resistance, the oil resistance is poor, the aging speed is faster, and the high temperature is more likely to cause the seal to aging and crack, resulting in transformer oil leakage. For example, the oil leakage of the No. 2 main transformer and the No. 2 transformer cooler oil is caused by the aging of the sealing rubber pad.

(2) The welding parts of the transformer have blisters. There are two main reasons for the blisters: (1) due to poor welding quality, there are sand holes in the welded parts; 2 due to serious corrosion of the welded parts, the oil in the sand is leaking.

(3) Oil leakage is caused by equipment maintenance and repair. In the transformer overhaul, according to the requirements of the transformer maintenance technical standard specification, the fasteners of the relevant parts should be tightened without being tightened or the spring pad is not installed, which will cause the fasteners to loosen and the seal is not tight, causing oil leakage. For example: the No. 2 main transformer low pressure side casing oil leakage.

(4) Oil leakage due to environmental reasons. In the winter, due to the sudden change of the weather, the thermal expansion and contraction caused the sealing of the relevant parts to cause oil leakage.

(5) Due to improper installation. The flange joint is uneven and uneven. During the installation process, the gasket can not be evenly stressed, resulting in uneven force on the sealing pad fixing bolt, and the flange joint variation is misaligned, causing leakage of the transformer oil. This phenomenon occurs mostly at the junction of the gas relay and the connection between the cooler and the body.

(6) The transformer is transferred to the maintenance state (higher temperature of the transformer oil), and the exit time is longer (especially in the autumn to winter). Due to the large difference in ambient temperature, the sealing rubber pad expands and contracts, causing the sealing pad. Shrinkage cracks cause leakage. For example, the No. 2 main transformer of the factory was withdrawn from operation on August 26 and put into operation in March of the second year. In December, the No. 2 and No. 4 cooler oil leaked.

3 Precautions

According to the above several oil leakage conditions, the full use of the motor to stop the oil immersed power transformer oil leakage treatment:

(1) Make full use of the inspection timing, and replace the new gasket with the oil leakage caused by the aging of the sealing gasket. For example, the No. 2, No. 3, and No. 4 main transformers used the overhaul opportunity to replace the main transformer cooler gaskets, eliminating hidden dangers.

(2) Effectively guarantee the quality of maintenance and repair, and prevent the loosening of the fasteners and the tight sealing caused by the fasteners being tightened without tightening or adding spring pads, causing oil leakage.

(3) Guarantee the quality of inspection, especially in the bad weather with sudden temperature difference, strengthen inspections, ensure the quality of the tour, carefully check the transformers for serious oil leakage, and find that serious oil leakage should be dealt with in a timely manner. Prevent equipment accidents.

(4) Quick sealing and plugging glue stick plugging. This method is used for short-term power failure of transformer, slight leakage and dripping, and need to be plugged. When using plugging bar to block leak, completely remove the leaking part. The dirt, oil, paint, and oxides make the metal part exposed to the original color, and then adjust the leaking glue according to the mixing ratio to block the leakage.
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With the continuous improvement of equipment management standards, higher operating standards have been proposed for the stable operation of large transformers. For many years, Juke Industrial, a power transformer manufacturer, has continuously accumulated processing experience and continuously improved preventive measures through the treatment of oil-immersed power transformer oil leakage problems, providing a reliable guarantee for transformer operation.