The traction dry transformer convey electric energy of three phase electric power system to one phase traction line which loaded separately. The two single phase line supply power to up-and-down locomotive separately. Under ideal condition the two one phase has the same loading. So the traction dry transformer as a transformer which three phase transformer change into two phase transformer. The traction dry type transformer is a power transformer with special voltage class that also a heart of transformer to meet the requirement of traction load change dramatically and external short circuit frequently. We often use three types which include three phase, three phase - two phase and single phase, so traction substation is also divided into three types with three phase, three phase - two phase and single phase.
The primary side of the traction transformer is bonded to two phases in the three-phase power system.One side of the secondary side is connected with the bus of the traction side, and the other end is connected with the track and grounding grid.The capacity utilization rate of traction transformer is high, but the negative sequence current generated by single-phase traction load in the power system is large, and the power supply to catenary cannot be realized by bilateral power supply.Therefore, this kind of junction line is only suitable for the situation where the power system capacity is large, the power network is relatively developed, and the three-phase load electricity can be reliably supplied by the local power grid.In addition, single-phase traction transformer according to the full insulation design manufacturing.
Traction dry type transformer is suitable for urban subway and rail transit. With the development of urban rail transit, it is widely used.There are three grades of voltage: 10, 20 and 35kV.From 12 pulse rectifier to 24 pulse, reducing harmonic pollution.The capacity is 800, 2500, 3300kVA and so on.