Product introduction

       The epoxy resin cast dry type transformer is developed independently by the Company with domestic and foreign advanced technology. In addition, production technology of proprietary intellectual property rights and strict quality control were adopted in manufacturing. Therefore, the product has advantages such as low loss, strong overload capacity, high short circuit resistance, small partial discharge, good lightning resistance, excellent cracking resistance, high reliability, long service life, moisture proof, mildew proof, salt spray resistance, flame retardant, pollution-free, small volume, low noise, light weight and automatic temperature control. It can be widely used in power transmission substation systems and is suitable for places of dense population, such as high-rise buildings, commercial centers, residential quarters, schools, hospitals, theaters, stations, ships, terminals and airports. It is also suitable for places of high requirement on fire prevention, high humidity and high maintenance difficulty, such as laboratory, museum, offshore drilling platform, metro, tunnel, petrochemical plant, transformer substation, combined power station, pump station and water supply station.

Structural features

Iron core

It is made of ultra thin high quality cold rolled grain oriented silicon steel sheet with full tapered connection of 45° and composed of five-stage joint stepping structure. The yoke is intensified by upper and lower steel strips. The core column is bound by polyester strip. The surface is painted with TW32-4 organic silicon self-drying insulation lacquer. Its no load loss might be reduced by 20%.The no load current might be reduced by 30%. Its noise is 5-10dB lower than similar domestic product. (This is the difference between our common product and other manufacturers. The Company made special studies on noise, and placed a corrugated rubber plate between the transformer core and the foot-pad to reduce vibration.) Plate type clamping structure of good ventilation is adopted.

Coil

The high voltage coil is constructed into a special pie structure. The pressure difference between pie windings is small. The voltage distribution of lightning impact is uniform and the anti-impact performance is good. The high voltage coil is made of Grade H polyester inferior amine enamel-cover low oxygen high conductivity copper wire. The space between outer and inner coil layers is filled with resin impregnation fiberglass mesh which improves distribution of the electric field and provides good permeability and invasion. The epoxy resin mixture is poured in the vacuum state. The poured resin mixture can completely diffuse into the gaps of the coil to effectively suppress the partial discharge phenomenon. The partial discharge amount is less than 5Pc. Low oxygen high conductivity copper wire was used as low voltage coil. It is made by winding of copper wire or copper foil windings of high-conductivity. Grade H prepreg epoxy resin DMD composite foil is used as interlayer insulation. What's more, the reactance height of low-voltage windings is almost the same. The axial electric power of the product is small when a short circuit occurs outside, so that it has excellent dynamic thermal stability.

Insulating system

The main insulating material is Grade H two-component cast epoxy resin. The filler is silica powder which is unlikely to deposit in resin. The coil poured has uniform distribution of filler and resin as well as isotropy of thermal transferring. The coefficient difference of linear expansion for insulating material composed of selected copper wire selected, etc. is small. The coil structure is reinforced by gridding cloth. Uniform distribution of resin and filler makes the coil free from influences of temperature change. The resin could not break if the state is changed from high temperature to low temperature suddenly. It solves the common difficulty which is common in cast of transformers.

Assembly structure

Arrangement of electric field, major insulation, minor insulation, etc, between positions of coil end and conductor is given full consideration. Enough insulation margins are reserved. Particularly, it also gives consideration to anti-short-circuit capacity of the transformer. For arrangement of internal and external structures, the support point of the cushion block is set on the force bearing point to make the support system more reliable. The structure has passed the verification of sudden short circuit. The structure is reasonable. 

Normal using environment

1. Surrounding air temperature: highest temperature: +40°C; lowest temperature: 25°C.

2. Altitude: no more than 1,000m (in case of more than 1,000m, it should be corrected according to the corresponding altitude).

3. Wind pressure: ≤700Pa;

4. Mounting gradient: ≤3°, places without frequent violent vibration and impact.

5. Surrounding air should be free from apparent pollution of explosive, corrosive or flammable gases.

6. Thermal rating: H (F if not marked).