Important MCQ on Electrical Machines- 6
Important Multiple Choice Questions on Electrical Machines 1. Can a 50Hz transformer be used for a 25Hz if the input voltage is maintained constant at the rated value corresponding to 50Hz? a) Yes. Since the voltage is constant, current levels will not change. b) No. Flux will be doubled which will drive the core excessive saturation. c) No. Owing to decreased reactance of transformer, input current will be doubled at load. d) Yes. At constant voltage, insulation will not be overstressed. 2. In a transformer, if the iron losses and copper losses are 40.5 kW and 50 kW respectively, then at what fraction of load will be the efficiency be maximum? a) 0.8 b) 0.57 c) 0.7 d...