electricalengineeringquestionanswer

Anna University Previous Year Question Papers For EEE 4th sem [1] Define the term synchronous speed [Dec-2003] For synchronous machines there exists a fixed relationship between number of poles P, frequency (f) and the speed of the machine. The speed of the synchronous machine for the given number of poles and the rated frequency is called the synchronous speed mentioned as NS. [2] Write an expression for synchronous speed (Dec-2004) An expression for synchronous speed is NS = 120f/P. Where f = frequency P = No of poles of the machine. [3] What does speed voltage mean? (Dec-2007) When the magnetic flux is constant as well as stationary and the coil rotates to cut the flux then EMF gets induced due to relative speed between flux and coil. This EMF is called speed EMF, rotational EMF or dynamically induced EMF. [4] Mention the factors on which hysteresis loss depends (Dec-2008) The hysteresis loss is directly proportional to the area under the hysteresis curve ie area of the hysteresis l...

Special Machines (Permanent Magnet Synchronous Motor)  Interview Questions [1] What is the PMSM? In medium and small size synchronous motors, DC field can be produced by permanent magnets. Such kind of motors are called as PMSM [2] What are the advantages and disadvantages of PMSM Advantages Elimination of field copper loss Higher power density Lower rotor inertia Robust construction Disadvantages Power rating low Motor power factor can not be controlled because of field excitation cannot be controlled [3] What are the classification of PMSM Based on construction     Surface mounted PMSM     Interior mounted PMSM Based on the nature of voltage induced     Sinusoidally excited     Trapezoidally excited [4] Give some applications of PMSM Robots Machine tools [5] Define torque angle The angle between excitation emf and supply voltage. This angle is called torque angle or load or power angle . [6] What are the different classifications of synchro...