In order to adapt to the use under the mine, the firm structure and short shape of the transformer is required. The transformer is not equipped with an oil conservator. There is a proper space above the oil level in the oil tank in case excessive pressure in the tank is produced when the vent hole on the tank cover is blocked. The mechanical strength of the oil tank should have the ability to withstand the pressure of 98Pa without water deformation. Measures to prevent water condensation shall be taken inside the box cover. Cable boxes are welded on both sides of the box wall for the primary and secondary leading out of cables.
For the mining transformer, it is used in the place with explosion danger in the coal mine. This kind of mining transformer is all encapsulated dry type. All joints of the shell shall be made according to the requirements of explosion-proof, and shall bear the internal pressure of 785kPa.
The cable of small transformer for lighting is led out through the outlet sleeve. Rubber washer is set in the outlet sleeve. After the cable passes through the washer and the outlet sleeve is tightened, the washer will compress the cable to ensure the sealing. The box shell is welded with a support skid, which can be placed and dragged horizontally, and vertically.
In order to adapt to the tunnel transportation, the height of the mining transformer should be low, so the diameter of the iron pillar can be larger. The explosion-proof surface of mining electric drill and lighting transformer shall be treated with antirust. The mining power transformer is allowed to be transported in the inclined tunnel which is 35 ° from the horizontal plane. Flameproof transformer, also known as explosion-proof transformer, shall be tested for moisture-proof and explosion-proof.
When it is required to adjust the output voltage of the transformer, the oil immersed mining transformer can be operated by off circuit tap changer. For the complete set of mining transformer substation, it should be carried out on the tap board on the shell. If the secondary voltage is increased, the negative tapping position shall be connected, otherwise the positive tapping shall be connected. When the mining transformer is transported, stored and used, it shall be protected from rain and moisture.