The Choice of Dry Type Transformer

1. About dry type transformers

Dry type transformers are transformers with iron cores and windings that are not impregnated with insulating oil. The cooling modes of dry type transformer are natural air cooling (AN) and forced air cooling (PF). The dry-type transformer has two types of structure: fixed insulation envelope (SCB type) and unencapsulated winding structure. From the relative position of the high and low voltage winding there are two concentric and overlapping. Concentric structure is simple and convenient to manufacture. Most dry transformers adopt this structure. Overlap type is mainly used for special transformer manufacturing.

2. Specification of Dry type transformer 

Use SCB - 11-1250 kva / 10 KV / 0.4 KV dry-type transformer as an example, to explain the meaning of dry type transformer model: in the above specifications, S three-phase power transformer, transformer winding for solid resin casting molding, C said in the letter C position G the winding insulation for the air outside, B is moored type winding, in the position of B R coil winding, 11 is a serial number, 1250 kva transformer rated capacity, 10 KV transformer primary side for rated voltage, 0.4 KV rated voltage for the transformer secondary side. 

3. Parameters of the dry type transformer

Dry type transformer technology parameters are: (1) the frequency 50 hz, (2) the light electricity ryukyu, require less than 4%, (3) low pressure intensity: 2 kv/min, no breakdown, (4) the low voltage side of insulation resistance of not less than 2 m Ω, (5) winding connection mode: / Y/yn0, with D/yn0,(6) coil allows the temperature of 100 k, (7 ) cooling method: natural air-cooled chiller or temperature control, end up noise coefficient is less than 30 db. 

4. Running environment demands 

Dry type transformer operation on the environment are as follows: (1) the environment temperature - 10-45 °, (2) the air relative humidity, daily average no greater than 95%, monthly average no greater than 90%, (3) altitude is below 1600 m (under the rated capacity).
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