Water Cooled Transformers.—A water cooled transformer is one in which water is the cooling agent, and, in most cases, oil is the medium by which heat is transferred from the coils to the water. In construction, pipes or a jacketed casing is provided through which the cooling water is passed by forced circulation, as shown in figs. 1,970 and 1,971.
Fig. 1,970.—Water cooled transformer with internal cooling coil, that is, with cooling coil within the transformer case. In this type, the cooling coil, through which the circulating water passes, is placed in the top of the case or tank, the latter is filled with oil so that the coil is submerged. The oil acts simply as a medium to transfer the heat generated by the transformer to the water circulating through the cooling coil. In operation a continual circulation of the oil takes place, as indicated by the arrows, due to the alternate heating and cooling it receives as it flows past the transformer coils and cooling coil respectively.
In some cases tubular conductors are provided for the circulation of the water.
Water cooled transformers may be divided into two classes, as those having:
- 1. Internal cooling coils;
- 2. External cooling coils.
Ques. Describe the first named type.
Ans. Inside the transformer case near the top is placed a coil of wrought iron pipe, through which the cooling water is pumped. The case is filled with oil, which by thermo-circulation flows upward through the coils, transferring the heat absorbed from the coils to the water; on cooling it becomes more dense (heavier) and descends along the inside surface of the casing.
