66kV ~ 110kV oil-immersed power transformers

Product Structure and Process Characteristics

The oil-immersed power transformers produced by our company are based on the advanced technologies at home and abroad, and are designed independently according to the characteristics of Chinese urban and rural power grid. Our product performance is better than the GB/T6451 Three-phase Oil-type Power Transformer Technical Parameters and Requirements, in full compliance with JB/T 3837 Transformer Product Model Preparation Method, and the manufacturing standards of GB1094 Power Transformers and the IEC standards recommended by the International Electrotechnical Commission.

The product is characterized by low loss, low noise, anti-leakage and no suspension core. It has extraordinary innovation in safety, reliability, economic efficiency and other aspects, so that it becomes a first-class technical product in China. The product has the following characteristics:

Iron Core of Transformer:Its iron core adopts multi-step stepping lap-type technology, the laminated piece adopts 45° oblique seam hole-free bandage structure, silicon steel sheet adopts advanced longitudinal and horizontal shear cutting, cutting mouth burr is not more than 0.02 mm. In addition, the advanced iron core stacking station, strict stacking and no pre-stack yoke process fully guarantee the grain orientation of silicon steel sheet, effectively reducing the no-load loss of the transformer.

The iron core adopts high-strength PET polyester banding design, clip structure adopts plate clamp pieces, thus reducing spurious loss. The iron yoke clamper adopts a unique clamping banding process, fully guaranteeing the iron core’s clamping degree.

At the same time, over years of development, the mature technology makes iron core, pull plate, roof beam, side beam and pad become a firm organic whole, and ensures that their on core sheet is in the best state to resist pressure, thereby reducing the transformer’s no-load loss and greatly lowering the noise of transformer.

Transformer Winding:The transformer’s high, medium, low and voltage-regulating coil shall wound on an insulating paper tube. Low-voltage winding mainly adopts spiral structure with axial oil passage.

High and medium voltage windings are made by composite wire wrapped with high-strength Dennison paper, which is imported from the United States, they can greatly increase the filling coefficient of transformer’s steel window, reduce the wire’s eddy current loss and circulation loss, and also improve the anti-short circuit capacity of the transformer.

There are locking stays (namely reinforced stays)inside and outside the winding. The winding’s radial fastening adopts the design of "0" margin, which greatly enhances the winding’s mechanical strength and short circuit resistance.

Meanwhile, the high, medium and low-voltage winding shall equipped with an oil-oriented structure, which reduces the temperature rise at the hottest points of winding, thus extending the transformer’s service life.

The on-load tap changing transformer has an independent voltage-regulating winding, so that the winding’s ampere turns are more balanced, the stability is improved, and the instability and deformation are eliminated, thus effectively reducing the transformer’s axial power caused by external short-circuit, and improving the transformer’s dynamic stability in the case of external fault.

Transformer Body Insulation: The transformer’s body insulation structure and winding process are completed in a fully sealed clean workshop, can meet the cleanliness requirements and constant body temperature requirements for high voltage, ultra-high voltage transformers, and further ensure the cleanliness and dryness of transformer body. Meanwhile, kerosene vapor-phase drying equipment is used to further ensure the cleanliness of the body. The lower pallet and upper pressure plate of the body all adopt electrical laminated wood with high mechanical strength and good electrical performance. The stays and pads in the transformer all have gone through high-precision cutting and rounding processes, greatly reducing the partial discharge. The steel clamp and steel nails have sufficient strength, the pressure contact surface that connects pressure sheet is designed to be the maximum. Support pads, stays and nails are arranged in a way to make the winding has balanced pressure, and enhance the overall stability. The body adopts overall package constant-pressure drying process, shortens the assembly time after winding is stabilized. The winding concentricity is adjusted, so that the cores will be consistent as much as possible, fully ensure that the coils have equal reactance height, keep even pressure on the winding, thereby improving each winding’s anti-short circuit capability. In addition, the lower clamp and lower fuel tank adopt a four-week steel positioning, and can be adjusted or locked through anti-pressure nails; upper beam and upper fuel tank lid adopt epoxy resin curing positioning, so the body can withstand the impact of variety of transport conditions in the tank, and does not shift when there is axial electric power in the operation.

Transformer Lead Wire: The transformer’s high and medium-voltage tap wires are fixed by a bracketand led to the switch, low-voltage lead copper wire is fixed onto the upper and lower clamps to improve the stability of lead wire. Besides, the coil binding standards and technological process greatly reduce the transformer’s partial discharge.

Transformer Tank: Large and medium transformers adopt bell-type fuel tank structure. Large-scale folding machine is used for corrugated molding. Various reinforced iron sheets and reinforced boards are cancelled. This not only greatly improves the mechanical strength of oil tank, but also reduces the leakage caused by welding, increases the effective cooling surface of the body, and improves the cooling effect. Meanwhile, due to the divergent effect of corrugated box wall, the noise of transformer is effectively reduced. The seal part of tank is treated with special processing, and the whole fuel tank adopts"shot peening" treatment, thus completely removing the oxidized surface of the box, as well as the sharp corners and welding slag caused by the processing, improving the adhesion of paint, and making the transformer more beautiful and durable. Radiator and other components are tested and inspected by simulating the field operation in harsh environmental conditions, thus effectively removing the leakage point. All the flange surfaces are refined, and set slotted position limiting structure. A high-quality oil-resistant, ozone-resistant acrylic rubber gasket is adopted to prevent the leakage of the transformer. In addition, the transformer’s upper and lower fuel tanks can be connected by bolts, and can also adopt seal structure along the upper and lower fuel tanks according to the user’s requirements.

Transformer Cooling and Accessories: It generally adopts air-cooled / self-cooled type, and has full-load operation when the fan starts, and begins naturally cooling when the fan stops, the cooling is 67% of full load. Chip radiator shall arranged in a reasonable and compact way, fans are generally hung over radiators, blowing in horizontal or vertical direction. The oil storage tank is generally capsule type, which has an oil-resistant, airtight capsule. It completely isolates from the oil of transformer from the air, and achieves full sealing. In addition, it can also adopt the expansion metal corrugated oil storage cabinet (internal oil cabinet or external oil cabinet) made by stainless steel. It is maintenance-free, and has reliable operation.

With advanced technologies, the Company has implemented perfect quality assurance system, adopted reliable product structure design and advanced technological processes, and ensured that our products have high reliability, low partial discharge, low loss and low noise.

Technical parameters and characteristics

Technical specification:

1.Voltage rating: 66kV ~ 110kV;

2.Voltage regulating method: on-load voltage regulating, no-load voltage regulating;

3.Rated capacity: 630 ~ 63000kVA (see the attached sheet, it can be customized according to users’ requirements);

4.Frequency: 50Hz;

5.Number of phases: 3-phase;

6.Label of connection group: according to national standards or users’ requirements;

7.Short circuit impedance: according to national standards or users’ requirements;

8.Application environment: according to national standards or users’ requirements;

9.Cooling method: oil-immersed self-cooling, air-cooled;

10.Insulation level: according to national standards.

Application environment and conditions

Device type: outdoor type

Ambient temperature: the maximum temperature +40 ℃, the minimum temperature -30 ℃

Altitude: ≤ 1000 m (The temperature rise should be modified if the altitude is higher than 1000 m)

Relative humidity: ≤ 90% (25℃)

Installation site: places with no corrosive gas and no obvious dirt

Notes for Customers

Please provide the following parameters when placing an order:

1.Product model

2.Rated capacity

3.Voltage combination

4.Voltage regulation range

5.Frequency

6.Label of connection group

7.Short circuit impedance

8.Other: special requirements should be noted.