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Dry Type Transformers :


Hangzhou Qiandian Special Transformers Co., Ltd, which is a sub-company of Hangzhou Qiantang River Electric Group Co., Ltd, uses international advance equipment to produce epoxy cast-resin dry type transformers since 1994, and the products are passed by the Ministry.



Technical Characteristics

    • The noise of transformer is originated from its core:

      our company adopts the first in our county the step-lap core lamination line imported from Georg Co. of Germany. The advanced technologies greatly improve the distribution of magnetic-flux in the core to reduce loss and noise.

      CAD and high quality silicon steel sheets are used and the flux density is made far lower than the saturation point, so harmonics in core and the noise are reduced.

      All clamped parts are buffered by silicon rubber and elastic components to reduce vibration and noise, and a specified resin is coated on the surface of core for sound insulation.

    • Low partial discharge and high electric intensity:

      The solid insulation composed of quality resin and glass fiber provides high dielectric strength and low partial discharge. The breakdown voltage is not less than 34kV/mm and the partial discharge can be less than 5pC.

    • Flame resistance and non environment pollution:

      When transformer is on fire, heat generated from the composite insulation is extremely small (about 6.5mJ/kg), so that the fire can be automatically extinguished.

    • Damp proof:

      It is able to operate at 100% of relative humidity, because both the core and the winding assembly are coated with resin. The transformer possesses high resistance to corrosion too. It also has high ability of over-loading high thermo-stability, less dimension and weight, easy to install and maintenance free, etc. Cast-resin dry type transformer is applicable to following cases, such as high buildings, commercial centers, airports, railway stations, wharfs, subways, plants, and underground substation.

Technical Specifications

    • Voltage class:

      10kV, 35kV

    • Model of voltage regulation:

      off-excitation or on-load tap changer

    • Tapping range:

      ¡À5%, ¡À2¡Á2.5%, or ¡À3¡Á2.5%

    • Power Capacity:


    • Frequency:

      50Hz, 60Hz

    • Phase No.:

      single phase or three phases

    • Vector Group:

      Yyn0 or Dyn11 or according to customers¡¯ requirements

    • Impedance voltage:

      please see data table or according to customers¡¯ requirements

    • Service condition:

      100% relative humidity, ambient temperature not more than 40¡æ or according to customers¡¯ requirements

    • Type of cooling:

      ONAN or ONAF

    • Guard class:

      IP00, IP20, IP23

    • Thermo-tolerance class of insulation: F

    • Insulation level: a. for 10kV class:

    • LI75AC35; b. for 35kV class:


Structure and construction features

    • Core

      The core is made of grain-oriented cold-rolled silicon steel sheet cut for step-lapping and laminated in the step-lap core lamination line from Georg Co. in Germany. In this way, the distribution of magnetic lines is improved and flux density in the step-lap joint is reduced. Owing to excellent equipment, quality silicon steel sheets and advanced technology, no-load performance of the core is greatly improved. Compared with traditional cores, no-load losses, no-load current and noise level have been reduced by 5%-6%, 20%-30% and 6% respectively.

    • Windings

      The windings are made of cast-resin high voltage windings. The HV winding is made in section-layer form, and LV winding is foil construction. Winding assembly is cast in the vacuum resin casting machine from Hedrich Co. in Germany. The resin materials are provided by CIBA-GEIGY Co. in Switzerland. The advanced technologies ensure minimum partial discharge and high ability of withstand short-circuit.

    • HV winding tapping range:

      Un¡À5% & Un¡À2¡Á2.5% on-load regulation.

      Temperature control device: Its functions are as follows:

      fault alarm, over temperature alarm and tripping, three-phase scanning, start and stop of air ventilation. It also can be equipped with computer remote interface.

      Cooling device:

      Axial fans are of low noise, even blast and easy installation. Forced cooling can enhance the capacity of transformers.

H class non-sealed type

H Class Insulation Non-sealed Windings Dry Type Transformers
Hangzhou Qiandian Special Transformers Co., Ltd produces H class insulation non-sealed windings dry type transformers, which are made of NOMEX insulated materials certificated by UL in USA. This type transformer is safe, reliable, energy-saving, fireproof, flameproof, and easy maintenance. Besides, it also has advantages such as advanced design, reasonable structure, and good aesthetic. Its main technical performance index is superior to National standard, such as partial discharge, no-load loss, load loss, noise and operating at humidity circumstance. It is suitable for regions with special requirements including dirty, wet surroundings near lake, river, sea, heavy-load region, and skyscrapers, airports, railway stations, wharfs, subway, hospitals, power stations, shopping centers, residential dense district, petrochemical, nuclear power stations, and nuclear powered submarines.


    • Due to elaborate design for the windings and vacuum pressure immersion treatment, which can ensure SGB 10 transformers minimum partial discharge(¡Ü5pc)£¬ without any chaps and reduction of insulation level during whole service life.

    • The HV winding is continuous structure. The LV winding is foil structure. Use vacuum pressure immersion and high temperature solidifying treatment and adopt the high strength biphenyl aether material or ceramic as support. So it has well insulation performance and short-circuit withstand ability.

    • Difficult to flame, flameproof, innocuous, non-pollution, self-extinguishing, fireproofs.

    • Even if burning under high temperature, SGB 10 transformers seldom bring any smoke.

Hermo-tolerance class of insulation:

H (180¡æ).

    • Insulation layer is very thin and equality, it has extremely over-load ability in short duration, and it is not necessary to force air cooling, it allows 120% over-load for long duration and 140% over-load for 3 hours. Due to anti-aging insulation material with bound, so it can reach full-load at ¡À50¡æ condition.

    • for 10kV class:

    • for 35kV class:


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