Selection of dry-type transformer and oil-immersed power tra

Dry-type transformer dry-type transformer refers to the core and winding is not immersed in insulating oil in the transformer. Dry-type transformer cooling methods have Natural Air Cooling (AN) and forced air cooling (PF) two. The dry-type transformer structure type has the fixed insulation envelope (SCB) and the non-envelope winding structure two kinds. From the relative position of the high and low voltage winding, there are two kinds of concentric and overlapping. The concentric type has a simple structure and is easy to manufacture. Most dry-type transformers use this structure. The overlap type is mainly used in the manufacture of the special transformer. 2. The specification of dry-type transformer takes the example of SCB-11-1250KVA/10KV/0.4 Kv dry-type transformer to explain the meaning of the model of dry-type transformer: in the above model specification, s stands for three-phase power transformer, c means that the transformer windings are resin-cast solid, at the position of the letter C, g means that the external insulating medium of the windings is air, b means that the windings are of the type B, r means that the windings are of the type B, 11 is the series number, 1250 KVA is the rated capacity of the transformer, 10KV is the rated voltage of the primary side of the transformer and 0.4 kv is the rated voltage of the secondary side of the transformer. 3. Technical parameters of dry-type transformer technical parameters of dry-type transformer are: 1 FREQUENCY 50HZ, 2 no-load current, less than 4% , 3 low-voltage withstand voltage strength: 2 Kv/min no breakdown, 4 insulation resistance low-voltage side not less than 2 M, 5 winding connection:/y/yn0, with d/yn0,6 coil allowed temperature rise 100K, 7 cooling mode: Natural Air Cooling or temperature controlled air cooling, 8 noise coefficient less than 30dB. Loss parameters of various capacity dry-type transformers (SCB type) are shown in Table 1. 4. dry-type Transformer Operating Environment Requirements dry-type transformer operating environment requirements are as follows: 1 Environmental Temperature-100 ° 45 ° , 2 air relative humidity: daily average not more than 95% , monthly average not more than 90% , below 1600 m sea level (below rated capacity). 5. The cost of dry-type transformer is more expensive than that of oil-immersed transformer. The capacity of oil-immersed transformer is larger than that of dry-type transformer. Dry-type transformers are used in underground floors, floors and crowded places. Oil-immersed transformers are used in independent substations. Dry-type transformers are generally used in box substations. When the space is large, the oil-immersed transformer is used, and when the space is crowded, the type transformer is used. When the regional climate is humid, use oil-immersed transformer. Dry-type transformers are used in places where "fire and explosion proof" is required. The load bearing capacity of dry-type transformers is worse than that of oil-immersed transformers. Dry-type transformers shall operate at rated capacity. The oil-immersed transformer may be overloaded for a short time. 6, SCB type dry-type transformer and SGB type transformer different in the winding: SCB Type dry-type Transformer low-voltage coil using foil winding. Winding configuration: Copper Foil single layer winding, interlayer material containing latent curing agent of the epoxy and secondary composite foil. Winding Material: oxygen-free copper with excellent conductivity, containing 99.99% copper. The low-voltage coil of SGB dry-type transformer is wound by wire. Winding structure: Cylindrical Coil, a number of ordinary glass wrapped flat copper wire. The short-circuit resistance of SGB dry-type transformer is better than SCB dry-type transformer. In terms of heat dissipation, SCB dry-type transformer to good type SGB transformer. SCB type dry transformer is lower than SGB type dry transformer in carrying load loss. In terms of temperature rise, the SCB radiator is dry and SGB. 7、 SGB、 SCB、 S13 type power transformer price comparison take the rated capacity 1250KVA power transformer as an example, find the same type manufacturer quotation on the net to compare. SGB11A-1250KVA/10KV/0.4 KV, SCB11 -- 1250kva/10KV/0.4 KV, S13 -- 1250kva/10KV/0.4 Kv power transformer, the quoted price of one plant in Wenzhou, Zhejiang Province is 93800 yuan/set, 95600 Yuan/set 59600 yuan/set respectively. From this we can see that the price difference between SCB and SGB is not big, dry-type transformer is about 1.5 times of oil-immersed transformer price. 8、 S13 OIL-IMMERSED POWER TRANSFORMER LOSS PARAMETERS S13 oil-immersed power transformer loss parameters as shown in Table 2. The no-load loss of dry-type transformer is larger than that of oil-immersed transformer. The load loss of dry-type transformer is smaller than that of oil-immersed transformer. 9. The Guide of power transformer selection should refer to GB/t17468-2008《 guide of power transformer selection 》 and GB4208-2008《 Ip code 》 to select the power transformer suitable for the environment. The general principle of selecting power transformer: When selecting technical parameters of transformer, the reliability of transformer as a whole should be taken as the basis, the advancement, rationality and economy of technical parameters should be comprehensively considered, and the operation mode should be combined, technical and economic indicators are proposed. At the same time, we should also consider the possible impact on the safe operation of the system, environmental protection, material saving, transportation and installation space, etc. . 10. Power transformer selection example three transformers (1250KVA transformer 2,400KVA1) originally designed for a new cold-rolled strip mill in an industrial platform are SCB type dry-type transformers. The owner of the unit in charge of the author to consult the price of these three transformers. Based on the site, environment and load conditions of the plant, the author suggests that oil-immersed sealed type S13m power transformer be adopted in cold strip mill. This factory accepted the author's suggestion, not only saved a lot of precious funds, but also economic and high-performance to meet the production requirements. Oil-immersed power transformer has mature technology, Natural Air Cooling, stable quality, strong anti-short-circuit ability, suitable for high humidity and high temperature environment, strong overload capacity, long service life and about two-thirds of the price of dry-type transformer. Therefore, unless there are fire requirements to choose dry-type transformer requirements, otherwise, should be preferred oil-immersed sealed power transformer.