CONSTRUCTION OF TRANSFORMER

CONSTRUCTION The main considerations in the construction of the transformer are simplicity and ease of construction, the economy of material, provision of insulation to withstand electrical stresses, mechanical strength to withstand the forces caused by heavy short circuit currents and ventilation to get rid of the heat due to the losses in the coils and the core.

Mainly there are two designs to meet these requirements

1. core type  

2. shell type

 

The distinction between the two types can be summed up by the fact that in the core type the windings encircle the core whereas in shell type the core encircles the windings. Out of the two, the core type is normally preferred because of the additional advantages of permitting visual inspection of the coils in case of fault and of greater ease in making repairs on the site of installation. It is to be noted that both the windings (primary and secondary or LT and HT) are wound on both the limbs of the core type as well as shell type. A portion of the LT winding in the form of a coil is placed close to the core from electrical stresses point of view and then over this, we have an HT coil and so on. Both the windings will be on both the limbs of the core type construction.