Core Type Transformer Construction and Winding

• Core type transformer In this type of transformer winding covers the large portion of core. Windings (LV and HV) are wound on the limb of the core which is made up of laminations. Fig. 1.2.1 shows the construction of core type transformer.
• The laminations which connects two vertical limbs is called as yoke. Depending upon the materials used for core its area may be larger than limb area or equal to limb area.

        Area of yoke = 1.15 to 1.25 time gross iron area for hot rolled steel,

• Generally to save the insulation cost low voltage winding is placed near the core, while high voltage winding is placed over the low voltage winding.
• Spacers of some insulating materials like wood, mica is placed between HV winding and LV winding which creates ducts to help cooling of windings.
• Also for maintenance coil can be easily removed by removing yoke portion.

This type of construction is more common in practice due to ease of manufacturing, increased cooling effect and easy maintenance.