Yuebian Electric Co.,Ltd is one of the leading China underground combined transformer manufacturers and suppliers, welcome to check underground combined transformer price with us.16.Underground combined transformerUnderground Combined TransformerMost combined transformers are powered by underground power cable and no incoming and outgoing cables buried underground can be seen from outside.Since there is no naked electrified part outside the transformer, no outside fence or restriction area is needed.The combined transformer allows unauthorized or occasional approach to the housing surface in design. Though mostly installed on ground,the unit is safe and reliable.Underground Combined Transformer is another kind of power distribution transformer. Fully installed underground. It is the "underground power distribution equipment" in true sense. The unit is generally installed in the maintenance hole of concealed ditch or small silo. With respect to the overall appearance, it is similar to the conventional power distribution transformer. However, it is underground and the high-low voltage wiring terminals must be fully insulated and sealed. Convenient and reliable operation should be considered in design.1.Terms and Definition1.1 Underground Combined TransformerA kind of corrosion resistant enclosed power distribution transformer and combined transformer that can be installed underground(or in ground pit)1.2 Ground PitThe site with water drainage and for underground installation of transformer, a certain space around the underground transformer shall be reserved at the site. The unit can be covered, but the ventilation hole and manhole shall be reserved.1.3 Product type2. Technical Features·Suitable for urban environment(installed underground or in pit),especially for the highly populated down towns.·Suitable for the lighting systems of street, expressway, bridge, tunnel, parking lot, airport harbor and scenic spot etc.·High&low voltage incoming and outgoing cables are connected fully enclosed, insulated and shielded.·The housing is made of anti-corrosion stainless steel, fully enclosed and can be immersed into water for a certain period of time.·The special situation of ventilation and heat radiation is fully considered with low loss and designed temperature.3.Structure3.1 Oil TankSince the primary equipment is shifted from ground to underground , various negative environmental factors, for example, moisture, water dipping, ventilation and heat radiation etc. have to be considered. The first consideration shall be given to the possibility that the underground transformer is immersed into water for short time, or the oil tank is immersed into water for long time. So, the oil tank of underground transformer must be fabricated with strong corrosion-proof materials and at protection level of IP 68. Therefore, the oil tank is made of corrosion-proof stainless steel, and the housing cover and the housing are permanently welded. The oil tank is in below structure, however, different from the conventional one, the corrugated wall only dissipates heat, does not expand. So, the height of corrugated wall is less than 160mm and made of stainless steel with min. thickness of 1.5mm,so that it can withstand big pressure. The tank does not deform under the pressure of 0.5kg,does not break or give way to leakage under the pressure of 1kg.3.2 Bushing10kV power cable is connected with high voltage sleeve adapter through elbow type separable cable terminals. The high voltage sleeve adapter is in special design and made with special process to guarantee the insulation distance within the oil level change range, the sealing against the housing, insulating fitting and sealing with elbow type cable adapter. The elbow type cable adapter is supported by a reinforcing bracket at the outside to improve its reliability. The low voltage cables go out in several modes and our company applies two. Low voltage cable conducting unit i.e., low voltage sealing sleeve is applied for the capacitance of max. 400kVA and the low voltage of single outgoing cable. The conventional low voltage sleeve is used for the low voltage of multi-cables and is placed into a enclosed housing. The multi-path technology is applied at the cable outlet to facilitate the cable installation and dis-assembly, which breaks away from the traditional method of asphaltum wrapping on low voltage sleeve.4. Temperature RiseAnother important issue is transformer temperature rise. Since underground transformer is installed in underground ditch or pit, the ventilation and heat dissipation are definitely worse than those on ground. We have considered in design the ambient temperature modification due to the enclosure that envelops the transformer. There is no national or industrial standard about underground transformer in China at present, so we refer to the parameters in Australian Standards AS1078(1984) Oil Dipping Transformer Load Guide and set the main performance parameters of transformer at type 11.Technical ParametersCapacity (kva)Po(W)Pk(75)Uk（%）Io（%）Outline drawingOutline dimension5010060042.1Pic 11260*610*1180501308702.0Pic 11280*610*12206315010401.9Pic 11300*610*12608018012501.8Pic 11320*610*130010020015001.6Pic 11340*740*134012524018001.5Pic 11360*740*138016027022001.4Pic 11380*740*144020033026001.3Pic 11400*740*148025040030501.2Pic 11460*790*156031548036501.1Pic 11460*790*156040057043001.0Pic 11490*820*160050068051001.0Pic 11510*850*164063081062004.50.9Pic 11650*890*164080098075000.8Pic 11680*930*168010001150103000.7Pic 11710*960*172012501360120000.6Pic 11750*1000*176016001640145000.6Pic 11800*1050*1800
