Electrical Machines The material used for commutator brushes is mostly mica. copper. carbon. cast iron. mica. copper. carbon. cast iron. 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 57.1%. 48.0%. 59.2%. 88.8%. 57.1%. 48.0%. 59.2%. 88.8%. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The heat transfer by convection in a transformer least depends on color of the paint. air velocity. surface area. temperature difference. color of the paint. air velocity. surface area. temperature difference. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines If Kh is hysteresis constant, f is supply frequency, Bm maximum flux density in core of transformer, the expression of hysteresis loss in transformer, is given by KhfBm. KhfBm3. Khf2Bm1.6. KhfBm1.6. KhfBm. KhfBm3. Khf2Bm1.6. KhfBm1.6. ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines The armature mmf in a dc machine is 1. stationary with respect to field poles 2. stationary with respect to armature 3. rotating with respect to field poles 4. rotating with respect to armature From these, the correct answer is 1, 3 2, 4 2, 3 1, 4 1, 3 2, 4 2, 3 1, 4 ANSWER DOWNLOAD EXAMIANS APP
Electrical Machines DC motors are stopped by opening line switches and not by forcing the handle of the motor starter back to OFF position. This is due to occurance of Heavy sparking at brushes. Heavy sparking at the first stud of starting resistance steps. Both of above. None of these. Heavy sparking at brushes. Heavy sparking at the first stud of starting resistance steps. Both of above. None of these. ANSWER DOWNLOAD EXAMIANS APP
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