Whatsapp
Overview
Three-phase oil-immersed transformer is an indispensable and important equipment in the power transmission and distribution system. It converts electric energy from one voltage level to another while keeping the frequency unchanged. This kind of transformer is widely used in medium and high voltage power systems due to its high efficiency, reliability and economy. In the structure of modern distribution network, three-phase oil-immersed transformer will play an increasingly important role. With the rapid development of society, three-phase oil-immersed transformer will continue to upgrade.
Basic structure and working principle
Core structure composition
Iron core: It is made of high-permeability silicon steel sheets stacked to form a magnetic circuit system and reduce eddy current loss
Winding: It includes high-voltage winding and low-voltage winding, usually wound with copper or aluminum conductors
Insulating oil: As an insulating and cooling medium, mineral oil or synthetic ester oil is usually used
Oil tank: A sealed container that holds the transformer body and insulating oil
Heat dissipation device: Including heat sink, heat pipe or cooling fan
Protective device: Oil level gauge, pressure relief valve, gas relay, etc.
Working principle
Three-phase oil-immersed transformer works based on the principle of electromagnetic induction. When the primary winding is connected to an AC power source, an alternating magnetic flux is generated in the iron core, which induces an electromotive force in the secondary winding. By changing the turns ratio of the primary and secondary windings, the voltage can be increased or decreased.
Main technical features
High efficiency: the efficiency of modern three-phase oil-immersed transformers can usually reach more than 98%
Good heat dissipation performance: the insulating oil not only provides insulation, but also effectively dissipates heat through natural convection or forced circulation
High insulation strength: the oil-paper insulation system can withstand high voltage stress
Overload capacity: has a certain short-term overload capacity
Long life: the design life is usually 25-30 years, and it can be longer with proper maintenance
Classification and application
Classification by use
Power transformer: used in power transmission and distribution systems, with a capacity ranging from hundreds of kVA to hundreds of MVA
Distribution transformer: used for terminal power distribution, usually not exceeding 2500kVA
Special transformer: such as electric furnace transformer, rectifier transformer, etc.
Classification by cooling method
Oil-immersed self-cooling (ONAN): relying on natural convection of oil and natural convection of air
Oil-immersed air-cooling (ONAF): adding fans to force air cooling
Forced oil circulation air-cooling (OFAF): oil pump forces oil circulation and Fan cooling
Forced oil circulation water cooling (OFWF): oil pump forced oil circulation plus water cooler
Maintenance and fault diagnosis
General maintenance items
Oil quality detection: regular testing of oil breakdown voltage, moisture content, acid value and dissolved gas
Winding insulation test: measuring winding resistance and insulation resistance
Mechanical inspection: check fasteners, tap changer operating mechanism, etc.
Cooling system maintenance: clean radiator, check fan and oil pump
Common faults and treatments
Insulation aging: predicted by dissolved gas analysis (DGA) in oil
Winding deformation: detection by frequency response analysis
Oil leakage: timely repair and oil replenishment
Tap changer failure: regular maintenance and replacement of worn parts
Development trend
Environmentally friendly insulating oil: biodegradable ester oil replaces mineral oil
Intelligent: integrated online monitoring system to achieve condition maintenance
New material application: amorphous alloy core reduces no-load loss
Compact design: reduce volume and increase power density
Conclusion
In the future, transformers with higher efficiency, longer life and lower loss will help build a more reliable and green power network and provide solid support for global energy transformation. LUGAO will continue to optimize design and enhance product quality in line with the trend of development to meet the various needs of customers around the world and is committed to providing customers with high-quality power distribution solutions from LUGAO.
