Power transformer is one of the main elements in the electric power industry. It is designed to convert electricity. Three-phase transformers received great popularity, because the losses in them are 12-15% less than in the number of three single-phase ones.
Until recently, only power transformers of the oil type were used in the electric power industry. However, over the past 40 years, in the lower and middle voltage classes, dry transformers, which are fire-environmentally friendly types of transformers, began to actively press them. In them, for insulation, the magnetic core and windings are not placed in transformer oil. The repair of the dry type transformers is easy now.
This dry type transformers differ significantly from traditionally made fire and environmentally unsafe oil-filled transformers, which must be installed in specially equipped rooms in order to prevent the possibility of oil fire and paper-oil insulation or put them in separate boxes with the output out. To all this, oil-filled transformers require constant maintenance, which is not required for dry transformers. This leads to additional maintenance costs.
Dry-type power transformers have several significant advantages, the main of which are:
Reliability – provides high resistance to alternating and shock voltage, the ability of the transformer to work with large overloads, high resistance to increased pollution, humidity and temperature extremes.
Profitability – no need to have specialized facilities for installing a transformer.
Environmentally friendly – the absence of oil in the transformer prevents the possibility of environmental pollution in the event of its leakage, the absence of caustic and toxic gases in the transformer, and a low noise level.
Resistance to weathering – the ability to maintain performance at high and low temperatures, high humidity, aggressive atmosphere containing salt.
Performance – the possibility of a 50 percent increase in transformer power due to the installation of a fan for cooling the transformer, several options for connection schemes.
Compactness – the space occupied by the transformer is minimal, due to the compact design of dry transformers, as a result of this, you can use the freed space with maximum benefit.
No need for maintenance – due to the design features of the transformer, maintenance is reduced to a visual inspection.
Improved performance – dry transformers have less loss of short circuit, no-load, high resistance to short circuit and long thermal loads.
Manufacturability – the same execution technology with an oil transformer, greater availability of materials for the manufacture of the transformer.
Single-phase dry type low-power transformers were used in radio engineering, automation, communications, signaling, etc. long enough. Back in the first half of the 20th century, the technology for manufacturing single-phase and three-phase dry power transformers used to convert electricity in the energy sector was developed much later – at the end of the last century.
Over a 30-year period of development of technologies and developments, the capacity of dry transformers was increased up to 40 times (from 0.5 to 20 MVA), the operating voltage was doubled (from 20 to 35 kV), the withstand voltage was almost three times (s 80 to 220 kV). This helped establish the serial production of various designs of such transformers. According to the international IEC standard, dry transformers are divided into the following classes: