1. what is a balanced 3system? 2.) what are advantages of 3? 3.) explain why it is true that without the transformer, it would simply not be possible to use electric power in many of the ways it is used today. 4.) explain how a transformer is able to change one ac voltage level to another voltage level and why the actual power supplied is not affected. 5.) what is a practical transformer? how does it differ from an ideal transformer? 6.) what is the purpose of power factor compensation? 7.) why is the name "synchronous" machine used? 8.) how does an induction motor differ from a synchronous machine? 9.) draw the single phase equivalent circuit of a 3induction motor. now draw the thevenin equivalent. 10.) list applications of the 3synchronous generator and the 3 induction motor.

Which of the following ziegler nichols tuning methods the response of the controller to a step input should exhibit an s-shaped curve? a)-open loop mode b)-closed loop mode c)-both modes (open & closed) d)-none of the modes (open & closed)

Ashielded metal arc-welding operation is accomplished in a work cell by a fitter and a welder. the fitter takes 5.5 min to load components into the welding fixture at the beginning of the work cycle, and 1.5 min to unload the completed weldment at the end of the cycle. the total ength of the weld seams 1200 mm, and the travel speed used by the welder averages 300 mm/min. every 600 mm of seam length, the welding stick must be changed, which takes 0.8 min. while the fitter is working, the welder is idle (resting): and while the welder is working the fitter is idle. (a) determine the average arc-on time as a fraction of the work cycle time. (b) how much improvement in arc-on time would result if the welder used flux-cored arc welding (manually operated), given that the spool of weld wire must be changed every 10 weldments, and it takes the welder 5.0 min to accomplish the change? (c) what are the production rates for these two cases (weldments completed per hour)? attach your work and solutions.

Around steel bar, made from material with a yield stress of 750mpa, is loaded so that it has stresses co locations of maximum normal stress and maximum shear stress. use maximum shear stress and maximum distortion energy theories to calculate the safety factors for initial yielding failures.