Assembly drawing and drawing of the magnetic system of the power transformer TRDN-25000/35

The object of the design is the TRDN-25000/35-U1 oil-immersed power transformer with a split winding of the LV into two identical ones with voltage regulation on the high side using an on-load tap-changer.

A power transformer with an on-load tap-changer with a rated power of 25 MVA and a rated voltage of 35 kV at an industrial network frequency of 50 Hz was developed. Transformer with split winding LV. The LV winding is made in the form of two identical concentric windings with a break inside the rod for the location of the terminals for connection to the inputs. The nominal stresses of the split winding links are the same.

Transformer parameters: TRDN-25000/35-U1 with Uvn = 15.75 kV±8·1.5%; Unn = 6.3/6.3 kV; D/D-D-0-0; ukz = 9.5%; p0 = 29 kW; rc = 145 kW; і0 = 0.7%.

A transformer with a flat blended magnet system of rod type.

There are 15 steps in the section of the rods, and 12 steps in the section of the yoke.

The rods are screed with glass tape additionally impregnated with varnish. The yoke is pressed with yoke beams, as well as steel half-bands, which are insulated from the yoke by electric cardboard tapes. Vertical pressing is carried out with the help of axial studs that are placed outside the magnet system and insulated from metal parts.

The tank is chosen as oval, with 9 radiators with bent pipes with built-in fans. Rotary blade motors are installed between the radiator pipes, the fan motor shaft should be positioned vertically. The fan motors are powered from a junction box, which in turn is connected to the control panel. Inside the junction box there is a short-circuit current protection system.

The transformer is equipped with an expander. The reamer is equipped with an air dryer with an oil seal. A gas relay is installed between the tank and the expander on the pipe connecting them. To control the temperature of the upper layers of oil, thermometric alarms are installed on the transformers.

A thermosiphon filter is installed separately, designed for continuous automatic oil regeneration and purification.

Bushings are installed on the tank lid. The bushings are used to connect the output ends of the windings of oil-immersed transformers to the external electrical network.

At the bottom of the tank there is a special tap for draining the oil or taking samples to diagnose it.