Electrical Machines The core flux in transformer depends mainly on supply voltage and frequency supply voltage supply voltage and load supply voltage, frequency and load supply voltage and frequency supply voltage supply voltage and load supply voltage, frequency and load ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is/are the necessary conditions for voltage build up in self excited generator? All of these Field winding resistance should be less than critical resistance. Poles should contain residual flux. Field winding should be properly connected to armature winding. All of these Field winding resistance should be less than critical resistance. Poles should contain residual flux. Field winding should be properly connected to armature winding. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines For satisfactory performance of 3-phase 480V, 60 Hz induction motor, the supply voltage at 50 Hz should be equal to 420 V. 350 V. 400 V. 480 V. 420 V. 350 V. 400 V. 480 V. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines Motors for fans and pumps are selected in the rpm range 1440 to 2880. 720 to 920. 375 to 500. 500 to 720. 1440 to 2880. 720 to 920. 375 to 500. 500 to 720. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.5 p.u 0.125 p.u 0.75 p.u 0.25 p.u 0.5 p.u 0.125 p.u 0.75 p.u 0.25 p.u ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The counter (or back) emf in a dc machine is 1. the same as generated emf in a dc motor 2. proportional to field flux and armature speed 3. not the same as generated emf in a dc motor 4.inversely proportional to field flux 5. proportional to number of armature conductors 6. constant from no load to full load From these, the correct answer is 1, 2, 5 2, 3, 6 2, 4, 5, 6 3, 4, 5 1, 2, 5 2, 3, 6 2, 4, 5, 6 3, 4, 5 ANSWER DOWNLOAD EXAMIANS APP
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