Power transformers are the most important components of an electrical grid. Transformers designs differ by the cooling and electrical insulation systems used. There are dry transformers and oil-immersed transformers.
Most of transformers in service are oil-immersed. Their tank, containing the core, is filled with oil. The oil removes heat and ensures dielectric strength of insulation. Transformers with an air cooling system are called dry-type transformers. Those usually have smaller capacity, such as 1000-1600 kVA and a voltage of 10-15 kV. There are also transformers with mixed oil/water cooling systems with forced oil circulation.
Oil immersed transformer structure
The basic elements of an oil-immersed and dry-type transformers are the same and consist of magnetic core, windings and bushings. The magnetic core provides a path for magnetic flow. Windings create a magnetic field and consist of a conductor coil, wrapped around the core and insulated with pressboard barriers and screens. Thickness of the winding insulation increases with voltage. Bushings connect transformer windings to a substation.
A characteristic feature of an oil-immersed transformer is the oil conservator. It simplifies operation by monitoring the oil level in a tank and providing the space for thermal expansion of the oil.
Oil is the basis of the insulation system of power transformers
Oil is also an important part of a transformer. It serves as a heat dissipation medium and as a dielectric.
During operation, transformer oil is under the influence of a number of negative factors: high temperature, oxygen, water, high voltage etc. which reduce oil performance over time. Contaminated oil becomes dangerous for the equipment.
GlobeCore has designed oil purification and regeneration plants that can connect directly to transformers. Changing of used electrical insulating oil in many cases does not guarantee the desired result, as many aging products remain in a tank. These contaminants enter new oil and intensify the aging process. The CMM-R unit by GlobeCore can solve this problem. An important feature of this unit is its ability to process insulating oil in transformers under load. The unit connects directly to a transformer and circulates oil in a closed loop with oil flow washing away all aging products. The oil regains all necessary properties and parameters to as good as new condition, and the transformer can continue to operate normally.
Regular regeneration of oil can significantly prolong service life, improve reliability of transformers and save costs on purchase and disposal of oil.