Our company's dry type transformer is made of epoxy resin and adopts foreign advanced technology and CAD design.  The core is manufactured with high quality cold rolled grain-oriented silicon steel and steps overlapping structure is also adopted for the core design, thus to greatly reduce no-load loss.  Winding is manufactured with high quality epoxy resin, coil casting process is completed by automatic vacuum casting equipments. The epoxy resin is with characteristics of good penetrability and no bubbles, so its partial discharging volume is small. Dry-type transformers with advantages of strong overload ability, good thermal stability, small size, light weight, easy to install, exemption from maintenance can be widely used in high-rise buildings, commercial centers, airports, railway stations, docks, subways, factories and underground distribution stations.

Products structure

Core: The core is manufactured with high quality cold rolled grain-oriented silicon steel and step overlapping structure is also adopted for the core design. Magnetic circuit structure is improved and the magnetic flux density of steps overlapping joints is lowered. Because of first-class equipments, high quality silicon steel and advanced technology , the no-load capacity is greatly improved. Compared with normal cores, no-load loss, no-load current and noise are respectively reduced by 5-6%, 20-30%, 6%.

Coil: HV winding is casted with high quality epoxy resin at vacuum state with pressure;  LV winding is manufactured with high quality foil conductor. Advanced technology guarantee the small partial discharging volume, high capacity of short circuit impendence. The regulation range of H.V winding is Un±5% and Un±2x2.5%, on-load regulation range is wider.

Temperature controlling device: Function with fault alarm, over-temperature alarm, over-temperature trip, three-phase inspection, start and stop air cooling devices, etc.

Cooling devices: Using axial fan with low noise, uniform wind and easy to install, etc. Installation of cooling fan can overload about 40% in the long term.

Technical features

1, Noise of transformers come from cores. Our factory makes use of advanced Step-Lap technology to improve magnetic distribution in core. With its special advantages, lower transformers’noise. 

2, Design of products adopts CAD. Choose high quality silicon steel and low flux density which can leave far away from the saturation point, so amount of harmonics will be decreased, then noise will be lowered.

3, All clamping parts are made of silicone rubber and elastic element  to butter, so can reduce the amplitude, noise, while the outer of core is coated with a certain thickness of the resin, it plays a sound effect.

4, Small partial discharging volume and high electric strength. Solid insulation combined with high quality epoxy and glass fiber has very high electric strength(breakdown strength is not less than 34kV/mm). Partial discharging volume is small , can be controlled within 10pc.

5, Flame retardant and no pollution to the environment. The heat produced when resin epoxy and glass fiber composite insulation materials burn is very small (about 6.5mJ/KG), so it is hard to flame and can extinguish automatically.

6,Damp proof, can safely work under conditions of 100% damp. Dry type transformer’s core is coated with epoxy and its winding is completely casted by epoxy resin, so it can work under 100% damp and has strong corrosion protection capacity.

Specification 

Voltage level: 6-35kV

Capacity: 30-20000kVA

Regulation mode and tapping range: Un±2x2.5% (or±5%) no excitation, Un±4x2.5% (or ±5%) on -load voltage regulation

Frequency: 50Hz

Phase: three-phase 

Vector group: Yyno; Dyn11; YNd11 (or according to customers’requirements)

Short-circuit impedance: standard impedance(see specification table)

Working environment: altitude less than 1000 meters; environment temperature lower than 40°C.(If the working surrounding exceeds these limits, special design and manufacturing process should be involved according to related standards)

Insulation and heat resisting level: F, the upper limit of temperature is 155 °C ,and the limit of temperature rise of the winding is 100K.

Cooling mode : natural air cooling (AN), forced air cooling (AF)

Insulation level:

A, 6kV-type transformer: main frequency withstand voltage is 25kV, impulse withstand voltage id 60kV

B, 10kV-type transformer: main frequency withstand voltage is 35kV, impulse withstand voltage id 75kV

C, 20kV-type transformer: main frequency withstand voltage is 50kV, impulse withstand voltage id 125kV

D, 35kV-type transformer: main frequency withstand voltage is 70kV, impulse withstand voltage id 170kV