Design and fabrication of test rig for flow calibration in transformers

Transformers are mostly used in electronic and electric power appliances. These are essential for the transmission, distribution, and utilization of electric power. There are different sizes of transformers known to us, which include from smaller units of thumbnail-sized, hidden in microphones to units weighing hundreds of tons used in the power grids. Tiny dry-type and liquid-immersed transformers are often self-cooled by natural convection and radiation heat dissipation. With the increase of power ratings, transformers are cooled usually by forced-air cooling, oil cooling, water-cooling, or combinations of these. This work comprises of an experimental study of oil Natural Air Forced (ONAF) type transformer cooling system to verify the design data supplied by the original equipment manufacturer. In this research a duct is designed and fabricated for experimental work. Air velocity of an axial fan is measured with hot wire anemometer for air flow rate calibration. The proposed results are that air flow rate is minimum at the center point of duct and increases from center to the side walls.