Three single-phase, 7200 volt to 480 volt, 100 kVA transformers are connected in a step-down bank with the 7200 windings connected in wye and the 480 volt windings connected in delta. What is the rated line-to-line voltage on the wye side? 1. 12,470 V
2. 7,200 V
3. 4.160 V
4. 14,400 V
5. None of the above

Along 8-cm diameter steam pipe whose external surface temperature is 900c connects two buildings. the pipe is exposed to ambient air at 70c with a wind speed of 50 km/hr blowing across the pipe. determine the heat loss from the pipe per unit length. (b) air at 500c enters a section of a rectangular duct (15 cm x 20 cm) at an average velocity of 7 m/s. if the walls of the duct are maintained at 100c. a) the length of the tube for an exit temperature of the air to be 40 0c. b)the rate of heat transfer from the air. c) the fan power needed to overcome the pressure drop in this section of the duct.