25mva 115kv 6.6 Three-Winding Load Tapping Power Transformer

Technical parameters:

Connection group:yn,d11
Winding combination:H-L
No-load current(%):0.5
No-load loss(kW):26.2
On-load loss(kW ):142
Lmpedance(%):10.5
Weight of active part(kg) Around:46.3ton
Transport weight(kg):Around 53.2 ton(filling with nitrogen)
Transport dimension (L W H mm):6920x4320x5310
Capacity:25000kva

Structure characteristic:

1,Iron core
1. 1The iron core adopts cold-rolled crystal-oriented silicon steel plate 30Z140 with high quality, low-loss, and no
time effect, sheared by Geroge line and with no burr. 1.2 Iron core adopts pulling board structure, the upper
and down yoke is clamped by board, to form the frame structure. The iron core adopts advanced lamination
process, which effectively controls the no-load loss and electro-magnetic noise.

2 Winding
2.1 Winding adopts mature structure, which ensure the reliability of transformer operation.
2.2 The insulation power field intensity between turns shall be controlled no greater than 1.6kV/mm.

3,Body
3.1 Body adopts mature insulation structure, and strictly guarantee the main axial insulation margin.
3.2 Body mostly adopt multi-coil whole assembly, processed in constant voltage and evaporation, which made
coil shrink evenly and with less rebounce, and enhance the electric strength and mechanical strength.
3.3 Adopt laminating wood board or thermal shaped insulation cardboard. Pressed tightly with pin, which ensure
the winding is constantly pressed tightly. 

4,leading wire
4.1 The layout of all leading wire is reasonable, which guarantees the enough electric distance and mechanical
strenth. 
4.2 All leading wire is cirlulized ,which guarantee the reliable wild or prize connection. 

5,Oil tank
5.1 Oil tank adopts structure of flat top, bell jar type, which add the mechanical strength of oil tank and also
make the appearance beautiful and graceful, site installation tend to be more convenient.
5.2 Pipeline with gas relay such as the oil tube and bushing hoist support on top of oil tank is with hoist
gradient, to facilitate the gas in transformer flow to gas relay.
5.3 Vacuum oiling is adopted, there is no leakage and permanent distortion in the following test. vacuum-
pumping :759mmHg load voltage test: bear 2 times the oil pressure of oil conservator oil surface for 24 hours.
5.4 The structure of transformer is convenient for disassembly and change of bushing and porcelain element.
5.5 The oil drip valve is set on the bottom of oil tank, sampling valve is set in the middle.
5.6 collective gas connecting tube is fixed on the bushing hoist support.
5.7 Transformer is of full-sealed structure, the upper and down oil tanks are required to welded fully. 

6,Oil conservation tank 
6.1 Adopt capsule type, finger type oil level indicator oil conservation tank. 
6.2 The structure is convenient for internal cleaning, the capacity can ensure no oil overflow in 40 ambient
temperature with full load, and oil shall be seen from oil level indicator before put into operation in -25.
6.3 Oil conservation tank is equipped with oil-sealed moisture absorber. 

7,Safety protection device:
7.1 Gas relay is fixed in transformer, the standard complies with ZBK41004-89Gas relay.
7.2 There is enough and reliable pressure release device, and matched with oil spray pipe, the direction of oil
spraying is downward. 

8,Oil temperature measuring device:
8.1 There is pipe support of mercury thermometer, which is  set on the top of oil tank.
8.2 There is temperature controller,  the accuracy of thermometer complies with the related standard. Quantity
and technical requirement shall as per tender document. 

9,Each component  of transformer shall be prefabricated once in manufacture factory, marked, to ensure the
smooth procedure of site assembly. Before Ex-factory, inner core shall be check, and clean the fifth in
transformer.