Common faults and troubleshooting methods of power transformers

The common faults and troubleshooting methods of power transformers can be summarized as follows:

1、 Common types of faults

1. Winding faults: including turn to turn short circuits, winding grounding, phase to phase short circuits, wire breaks, and open joints. These faults may be caused by factors such as local insulation damage, poor heat dissipation, long-term overload, and poor manufacturing processes.

2. Casing failure: Common causes include explosion, flash off, and oil leakage. The reasons include poor sealing, deterioration of insulation due to moisture, improper configuration of respirators, poor porcelain quality with sand holes or cracks, and severe fouling of the casing.

3. Core failure: including local overheating and melting caused by insulation damage between silicon steel sheets, short circuits formed by insulation damage of through bolts, and heating and insulation damage caused by magnetic leakage inside the oil tank.

4. Transformer oil failure: Insulation oil may experience a decrease in electrical insulation performance due to high temperature oxidation and moisture absorption, blockage of oil channels by oil sludge deposition affecting heat dissipation, and flashover discharge caused by reduced oil insulation.

5. Excessive temperature rise: Due to factors such as excessive transformer load, poor cooling system, or insufficient cooling medium, excessive temperature rise may cause insulation material aging and electrical fires.

6. Cooling system failure: including blockage, leakage, and cooling fan failure of the cooler, which can affect the normal operation and temperature control of the transformer.

2、 Handling method

1. Winding fault handling: For winding faults such as inter turn short circuits, they should be detected and handled in a timely manner to avoid the fault from expanding. It may be necessary to perform a hanging core inspection, measure the DC resistance of each phase winding and compare them, identify the fault point, and repair or replace it.

2. Casing fault handling: For casing faults, the sealing condition should be checked, defective casings should be replaced, dirt should be cleaned, and the respirator configuration should be correct and the moisture absorbent should be effective.

3. Iron core fault handling: For iron core faults, a visual inspection should be carried out, the insulation resistance between the pieces should be measured, and the damaged parts should be painted or replaced.

4. Transformer oil fault handling: The insulation performance of transformer oil should be regularly tested, filtered or replaced to remove impurities and moisture, and maintain good insulation performance of the oil.

5. Treatment of excessive temperature rise: Adjust the transformer load, enhance the cooling system effect, such as cleaning the cooler and ensuring smooth flow of cooling medium, and consider measures such as increasing transformer capacity or reducing load to reduce temperature rise.

6. Handling of cooling system faults: For cooling system faults, the cooler should be cleaned, leakage points repaired, damaged fans replaced, etc., to ensure the normal operation of the cooling system.

In addition, for all types of faults, regular preventive tests and maintenance work should be carried out, as well as strengthened inspection and maintenance work during operation, to timely discover and deal with potential fault points, ensuring the safe and stable operation of transformers.