25 – 2500 kVA in power interval, hight voltaj level up to 36 kV, single or three-phase, oil immersed, naturel cooling (ONAN), no-load tap changer or with load automatic tap changer, both outdoor and indoor, are designed at form.

Structure of core and windings of transformers with oil conservator tank is same with hermetically sealed transformers.

Oil of the transformers expand with rise of the temperature. Dimensions of oil conservator tank of transformers is designed this its increase will store at form.

Transformers with oil conservator tank are open to atmosphere. Pressure of the oil changes in consequence thermic effects. The slica gel(air dryer) that being on conservator tank is got humidity of the air and it provides ingress-egress of the air.

Slica gel of transformer with oil conservator tank that works in the enterprise loses its feature in the course of the time. The oil is got humidity and is broken down its structure. Therefore the slica gel must change in specific periods and by-pass voltage of sample that gets from the oil must measure.