Electrical Machines Maximum allowable tan - delta (tanδ) of dielectric dispassion factor of power transformer insulating oil is generally taken as 2 at 90°C. 1 at 90°C. 3 at 90°C. 0.5 at 90°C. 2 at 90°C. 1 at 90°C. 3 at 90°C. 0.5 at 90°C. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be 48.0%. 59.2%. 57.1%. 88.8%. 48.0%. 59.2%. 57.1%. 88.8%. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is/are the necessary conditions for voltage build up in self excited generator? Field winding should be properly connected to armature winding. All of these Poles should contain residual flux. Field winding resistance should be less than critical resistance. Field winding should be properly connected to armature winding. All of these Poles should contain residual flux. Field winding resistance should be less than critical resistance. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines No load test on induction motor is conducted to find which of the following losses? Stator copper loss Stator core loss Rotational loss All of these Stator copper loss Stator core loss Rotational loss All of these ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines What is power factor of a 3 - φ induction motor at no load? Equal to 1. Low. High. Same as full load. Equal to 1. Low. High. Same as full load. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The emf induced in a conductor rotating in a bipolar field is DC. both of above. None of these AC. DC. both of above. None of these AC. ANSWER DOWNLOAD EXAMIANS APP
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