Principle and maintenance in operation of dry-type transformers

Dry-type transformers are transformers that do not use oil as a cooling medium. Compared with oil-immersed transformers, they have the advantages of no oil pollution, good fire resistance, and simple maintenance. They are widely used in places with high safety and environmental protection requirements such as high-rise buildings, commercial centers, and airports. A thorough understanding of the working principle and maintenance methods of dry-type transformers can improve the operating efficiency and reliability of transformers and extend their service life.

Principle of dry-type transformer

The basic principle of the transformer lies in its iron core and the two windings on the iron core. There is only magnetic coupling between the two windings but no electrical connection. When an alternating voltage is applied to the primary winding, an alternating magnetic flux that links the primary and secondary windings will be generated, thereby inducing electromotive forces e1 and e2 in the two windings respectively. The magnitude of the induced electromotive force follows Faraday's law of electromagnetic induction.

The electromagnetic induction phenomenon is the phenomenon that the change of magnetic flux leads to the generation of induced electromotive force. This phenomenon needs to meet two conditions: first, the magnetic flux must change; second, the number of turns of the primary and secondary windings must be unequal. Only in this way can the voltage conversion be achieved.

Maintenance in operation of dry-type transformers

Daily inspection: Daily inspection should include appearance inspection, temperature monitoring and sound monitoring. The operation and maintenance personnel should regularly check whether there are abnormal phenomena such as cracks and discoloration on the surface of the transformer, use an infrared thermometer to measure the temperature of each part, and pay attention to monitoring whether there is abnormal vibration or noise. Temperature is an important indicator reflecting the operating status of the transformer. The hot spot temperature of the winding should not usually exceed the heat resistance level of the insulation material.

Regular maintenance: Check the appearance and connection parts of the transformer to ensure that there is no looseness or damage. Check whether the temperature sensor and control system are working properly to ensure that the transformer operates within the normal temperature range. Clean the dust and debris around the transformer and keep it well ventilated.

‌Troubleshooting‌: If the transformer is found to be overheating, making abnormal noise or deteriorating electrical performance, it should be stopped and checked in time. Check the insulation of the windings and core to ensure that there is no short circuit or open circuit. For epoxy resin cast dry-type transformers, it is also necessary to check whether the epoxy resin is aged or cracked.

With its advantages of safety, environmental protection, and easy maintenance, dry-type transformers have become an indispensable equipment in modern power systems. By deeply understanding its working principle and structural characteristics, maintenance personnel can carry out daily management and fault prevention more effectively. Standardized maintenance can not only extend the life of the equipment, but also significantly improve the reliability of power supply.

With the advancement of materials science and manufacturing technology, the performance of dry-type transformers will continue to improve and the application field will be further expanded. In the future, the application of intelligent monitoring technology will make the status assessment of dry-type transformers more accurate and the maintenance management more efficient.